• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

Card Range To Study



Play button


Play button




Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

635 Cards in this Set

  • Front
  • Back
In what types of settings are PTAs employed? ***
- outpatient clinics
- inpatient rehabilitation centers
- extended care and pediatric facilities
- school systems
- home health agencies
Describe the difference between the traditional model and the health status model of disablement. ***
- the traditional model focuses on pathology and the clinical course of disease

- the health status model is based on the disablement process and focuses more on functional status rather than on the disease/pathology itself
Who was Saad Nagi? ***
a sociologist who developed this model that describes the relationship between health and function
What are the four components of the Nagi disablement model? ***
- disease (pathology)
- impairments
- functional limitations
- disability
As the health of the individual declines, what occurs in the disablement process? ***
- the person may initially be diagnosed with a disease, but have no outward signs of impairment

- the disease may progress, potentially causing a decline in health and giving rise to impairments

- the impairments may or may not lead to functional limitations (e.g, a patient may have the impairment of decreased ROM, but if the ROM is a functional range, may be able to do all necessary ADLs without showing limitations)

- if the decline in health caused functional limitations, these limitations may further cause disability
What is disease? ***
- "a pathologic state manifested by the presence of signs and symptoms that disrupt an individual’s homeostasis or internal balance” (Martin and Kessler 2007)

- e.g., Parkinson’s Disease, CVA, MS
What is an impairment? ***
- “an alteration in anatomic, physiologic, or psychological structures or functions” (Martin and Kessler 2007)

- e.g., examples: decreased strength, decreased ROM, decreased cadence

(signs that manifest at the organ or organ system level)
What are functional limitations? ***
- “occurrences resulting from impairments that become evident when an individual is unable to perform everyday activities that are considered part of the person’s daily routine.” (Martin and Kessler 2007)

- e.g., inability to tolerate sitting > 10 mins secondary to increased pain and radicular symptoms due to HNP
What is a disability? ***
- “results when functional limitations become so great that the person is unable to meet age-specific expectations within the social or physical environment.” (Verbrugge and Jette, 1994)

- e.g., unable to tolerate 40 hour work week
How is the Nagi Disablement Model incorporated into the Guide to Physical Therapist Practice? ***
- directs PTs to focus on treatment and pathology with objectives of improving functional ability, enabling performance of ADLs, preventing progression from one stage to the next

- outcomes are directed toward maximum independent function

- PT promotes wellness and fitness
In what aspects does the functional performance of an individual vary? ***
- personal characteristics
----- physical ability
----- emotional status
----- cognitive ability

- environment
----- home
----- community

- social expectations
----- family
----- community
----- culture
What roles does the PT carry out in patient management? ***
- examination
- evaluation
- diagnosis
- prognosis (including plan of care)
- intervention
- outcomes
What functions are PTAs *NOT* permitted to carry out with respect to patient management? ***
- interpretation of referral
- initial examination, evaluation, diagnosis, prognosis

- determination of whether it is appropriate to delegate interventions to a PTA or not (based on PTA's skills, training, education, etc.)
- development and modification of Plan of Care (PTAs can modify an intervention within the POC, however)
- reexamination and revision of POC

- establishment of discharge plan and documentation
- oversight of documentation
What roles do PTAs play in treating patients with neurological deficits? ***
- transfer activities
- gait training/functional training
- ADL training

- various manual techniques
- application of modalities as indicated

- documenting progress
- patient and family education
How does the PTA function as a member of a health care team? ***
- PTAs function as members of healthcare teams in all treatment settings

- teams may include, but are not limited to, the following disciplines:
----- speech therapy
----- occupational therapy
----- nursing
----- social work
----- respiratory therapy

(this "team" concept is true for all patients, but especially in the cases of neuro patients who generally require concurrent interventions from multiple disciplines; PTAs need to be proactive in seeking out cooperation among the disciplines--e.g., a patient may be unable to speak but communicates via sign language, you may need to seek out the SLP to learn some signs and what specific signs your patient has been using)
What are the two ANATOMICAL divisions of the nervous system? ***
- central nervous system (CNS)

- peripheral nervous system (PNS)
What comprises the CNS? ***
- brain

- spinal cord
What comprises the PNS? ***
- everything except the brain and spinal cord

What protective tissue surrounds the brain? ***

(dura mater, arachnoid, pia mater)
What fluid flows through ventricles in the brain? ***
cerebral spinal fluid (CSF)
What is the general function of the brain? ***
receives (via white matter) and processes (within gray matter) sensory information for motor performance
Of what tissue is white matter comprised? ***
myelinated axons
Of what tissue is gray matter comprised? ***
neuronal cell bodies and dendrites
What are the major components of the brain? ***
- cerebrum
- cerebellum
- brain stem (midbrain, pons, medulla oblongata)
What are the components of the brain stem? ***
- midbrain
- pons
- medulla oblongata
What is the function of the brain stem? ***
- direct continuance of spinal cord cranially

- link between spinal cord, cerebellum, cerebrum

- gives rise to cranial nerves (which are part of the PNS!!)
What is the function of the cerebellum? ***
- coordinating skilled voluntary movements (e.g., enabling you to touch your nose gently, vice hit yourself in nose)
- integrating, coordinating, and executing multijoint movements

- regulating initiation, timing, sequencing, and force generation of muscle contractions
- sequencing order of muscle firing when a group of muscles work together to perform a movement

- comparing actual motor performance with that which is anticipated
- controlling balance and equilibrium
What is the function of the cerebrum? ***
- center for highest mental functions

- two cerebral hemispheres make up largest part of brain, or the uppermost portion

- hemispheres control opposite sides of body's major structures
What structures comprise the cerebrum? ***
- cerebral cortex (gray matter)
- subcortical white matter fiber tracts

- thalamus
- hypothalamus

- basal ganglia
- corpus callosum
Name the lobes of the cerebrum. ***
- frontal lobe
- parietal lobe
- temporal lobe
- occipital lobe
Where is the motor speech area of Broca located? ***
frontal lobe, left hemisphere
What is the corpus callosum? ***
- a wide, flat bundle of neural fibers beneath the cortex
- largest white matter structure in the brain

- connects the left and right cerebral hemispheres
- facilitates interhemispheric communication
What pathology is associated with cell death within the substantia nigra? ***
Parkinson's Disease

(the death of dopamine-producing cells)
Is the spinal cord also protected by meninges? ***
yes, the same as the brain

(dura mater, arachnoid, pia mater)
Describe the central canal of the spinal cord. ***
- narrow central canal through the center of the spinal cord

- filled with CSF

- disappears by adulthood except at cervical levels
What is the function of the spinal cord? ***
- communication link between brain and PNS (body)

- pathway for sensory (afferent) information from PNS to brain (receptor…nerve…spinal cord…brain)

- pathway for motor (efferent) info from brain to PNS (brain…spinal cord…nerve…glands/muscles)
What comprises the spinal cord? ***
groups of neurons in the form of fiber bundles (tracts, fasiculi, columns, funiculi—bundles of axons/fibers)
What comprises the PNS? ***
- formed by the nerves leading to and from CNS

- nerves contain nerve fibers that conduct afferent/efferent information to/from CNS

- contains cranial nerves (12 pair) and spinal nerves (31 pair)
What are the FUNCTIONAL divisions of the nervous system? ***

- Autonomic (visceral) Nervous System (ANS)

- Somatic (body) Nervous System (SNS)

(these divisions are composed of both CNS and PNS components)
What is the function of the ANS? ***
- innervates smooth muscles and glands, blood vessels

- relays sensory/motor information

- involuntary
What is the function of the SNS? ***
- innervates muscles, skin, joints, mucous membranes

- relays sensory/motor information

- voluntary
What is a neuron? ***
- specialized cell of nervous system

- functional unit of nervous system
What are the three basic components of a neuron? ***
- cell body
- dendrite
- axon
What is the structure and function of a neuronal cell body? ***
- expanded portion of cell
- contains nucleus and organelles

- metabolic center of neuron (protein synthesis, etc.)
- processes incoming information
What is the structure and function of a neuronal cell dendrite? ***
- many threadlike projections radiating from cell body

- receptive part of neuron
- receives information from the environment or other neurons and transmits that information toward the cell body, where it is processed
What is the structure and function of a neuronal cell axon? ***
- single tubular extension of cell membrane comprised of many neurofilaments
- length varies from one millimeter to one meter

- most neuronal axons are myelinated (wrapped in concentric layers of fatty white substance called myelin) which serves to protect and insulate axon and enhance speed of electrical conduction

- branches at terminal end (sometimes 2-300 times)

- transports cellular materials to/from terminal endings
- conducts information (in form of action potentials) away from cell body to target cells such as muscle cells, glands, or other neurons
Which functional division of the nervous system conducts each of the following: ***

- innervates glands
- innervates skeletal muscle
- innervates mucous membranes
- innervates smooth muscle
- innervates blood vessels
- SNS (somewhat counterintuitive--may be good test question; actually the book contradicts this lecture slide, saying ANS)
How do neurons differ from other cells of the body? ***
- they are specialized for conduction of electrical impulses which transmit information (afferent/efferent) within the nervous system

- they require a constant supply of glucose and oxygen from arterial blood supply

- they do not multiply, and have little to no regeneration potential
Name three neuroglia. ***
- astrocytes
- oligodendrocytes
- microglia
What are neuroglia and what are their functions? ***
- cells composed of connective tissue, not specialized nerve tissue
- outnumber neurons in brain & spinal cord by 10 to 1
- do not form synapses

- they surround neurons and hold them in place (the word "glia" is from the Greek word for glue; they can be thought of as the "glue" of the nervous system, but also carry out the following functions:)

- supply nutrients and oxygen to neurons
- insulate one neuron from another
- destroy pathogens and remove dead neurons
- modulate neurotransmission, but the mechanism is not well understood
What is the function of an astrocyte? ***
- most abundant type of macroglial cell
- support neurons anatomically & metabolically
- aid in nervous system tissue repair

- form barrier between blood vessels and neurons (vascular link) and serve to restrict certain substances from entering
- play a role in maintaining a constant environment within and around brain so that normal function continues and foreign or harmful substances are kept out (“Blood-brain” barrier – restricts diffusion of some drugs into CNS)

- crucial in clearance of neurotransmitters from within the synaptic cleft, prevent toxic build-up of certain neurotransmitters
What is the function of an oligodendrocyte? ***
- form myelin, which wraps around CNS axons

(like Schwann cells in PNS)
What is the function of microglia? ***
- they are the macrophages/scavengers of CNS

- they remove cellular debris following brain/spinal cord damage or infection and assist with nervous system repair after injury
Why are glial cells able to divide? What does this predispose them to? ***
- they can divide (unlike neurons) because they are connective tissue, not nervous tissue

- this makes them highly susceptible to cancer
(most tumors of CNS are glial in origin; astrocytomas, glioblastomas, oligodendromas)
Name three types of nerve fibers. ***
- A fibers
- B fibers
- C fibers
Characteristics of an A fiber ***
- largest diameters
- myelinated
- conduct rapidly
- conduct motor and sensory impulses
Characteristics of a B fiber ***
- smaller than A fibers
- myelinated
- conduct slowly
- serve autonomic functions
Which types of nerve fibers are myelinated? Unmyelinated? ***
- A and B fibers

- C fibers
Rank the conduction velocity of nerve fibers from slowest to fastest. ***
- C
- B
- A
Characteristics of a C fiber ***
- smallest
- unmyelinated
- conduct impulses most slowly
- conduct pain (sensory) impulses and autonomic functions
Which types of nerve fibers conduct sensory (afferent) impulses? ***
A and C
Which types of nerve fibers conduct autonomic impulses? ***
B and C
Which types of nerve fibers conduct motor (efferent) impulses? ***
Describe gray matter. ***
- nervous tissue composed of dense collections of nerve cell bodies (grayish in color);

- comprise the cerebral cortex (outer layer of cerebrum) and innermost portion of spinal cord
Describe white matter. ***
- areas of nervous tissue in CNS composed of myelinated axons (glistening white color due to fat content) that carry information away from cell bodies
What structures/tissues comprise white matter? ***
- tracts/funiculi (vertical projections – spinal cord)

- association fibers (within hemispheres)

- commissure fibers (between hemispheres; e.g., corpus callosum)
What structures/tissues comprise gray matter? ***
- nuclei: nerve cells with a common function; grouped together; within CNS

- ganglia: nerve cells with common function: grouped together; outside of CNS (usually) (e.g., dorsal root ganglia)
What is the primary function of neurons? ***
transmission of information to other nerve cells (neurons) muscle cells, or glandular cells
Describe the general route of transmission of nerve impulses. ***
- stimulation of sensory neurons (from either internal or external environment)
- reception by sensory neurons

- transmission (conduction of impulse) to CNS
- integration (processing) of info by CNS & decision is made
- transmission (conduction of impulse) to PNS

- response by effector (muscle contraction, glandular secretion)
The human nervous system is a three-neuron system. List the three types and describe each. ***
- sensory (afferent) neuron - carries information from environment to brain (dorsally)

- motor (efferent) neuron - carries information from brain to environment/effector (ventrally)

- interneuron - between sensory/motor neurons, increase ability of NS to process/modify responses – higher level of mental/motor function
If the nervous system is the communication system of the body, how is that communication carried out between neurons? ***
- occurs as a result of transmission of electrical impulses between neurons

- transmission of impulse occurs as a result of the electrical properties of the neuron's cell membrane
What chemical elements are found inside/outside the neuronal cell membrane? What purpose do they serve? ***
- cell membrane separates extracellular fluid from intracellular fluid (Na+ & Cl- outside; K+ and proteins inside)

- cell membrane actively maintains a difference in ionic concentrations on either side; (inside slightly negative (K+ and anions) (outside slightly positive (Na++)

- difference in charge = biological battery = polarization
What does "polarization" of a nerve cell mean? ***
it means the membrane exhibits the potential to do work (exhibits excitability)
What does "excitability" mean with respect to nerve cells? ***
it means the membrane has the potential to conduct electrical impulses
What is the RMP of a nerve cell? ***
- the resting membrane potential

- the actual negative voltage across membrane of resting cells

- (-70mV inside cell membrane; depending on K+ concentration)
(other sources say -65mV)
Describe the propagation of an action potential. ***
- depolarizing current passively spreads down the axon, causing the interior of the axon to become more positive than when the membrane is resting

- in the adjacent membrane, when the depolarizing current reaches threshold level, Na+ channels open, causing rapid depolarization of the membrane

- an action potential is generated, and the depolarizing current continues to propagate down the axon
From what stimuli may excitation of a neuronal cell membrane result? ***
- mechanical (pressure)
- electrical
- chemical (neurotransmitter)
What two states may be created by changes in polarity of a nerve cell? ***
- depolarization – inside of cell membrane becomes more positive, increasing membrane excitability


- hyperpolarization – inside of cell membrane becomes more negative, decreasing membrane excitability/increasing inhibition
If depolarization of a nerve cell is sufficient, a(n) ______ ______ is created. ***
action potential
What is an action potential? ***
a stereotyped electrical message that passes along the axon from cell body to terminal branches (synapse)
In what manner is a portion of an action potential relayed? ***
- it isn't

- action potentials are all or nothing impulses
Which of the following variable(s) may be changed in the transmission of an action potential? (For example, to indicate increased urgency of the stimulus.) ***

- amplitude?
- duration?
- conduction velocity?
- amplitude and duration are always the same for any given type of neuron (no variation of strength), but

- conduction velocity (speed of transmission) can vary, depending on the type of axon
How does diameter of the fiber affect transmission of action potentials? ***
- smaller diameter - slower propagation of action potential

- larger diameter - faster propagation of action potential
How does myelination (or lack thereof) of the fiber affect transmission of action potentials? ***
- unmyelinated axon - slower propagation

- myelinated axon - faster propagation (up to 50 times faster)
How are nerve cell axons myelinated in: ***
- the CNS?
- the PNS?
- oligodendrocytes

- Schwann cells
What are the nodes of Ranvier? ***
interruptions (gaps) between the myelin sheaths covering the axon
Describe saltatory conduction. ***
- electrical impulses depolarize only at nodes of Ranvier instead of along the entire axonal membrane

- action potentials “jump” from node to node

- this increases the conduction velocity of the action potential

- this means of conduction is both faster and more energy efficient than via the unmyelinated method
How does multiple sclerosis affect myelin? ***
- it is a demyelinating disease that affects areas of the CNS (spinal cord, brainstem, cerebellum, cerebrum)

- apparent (?) viral response whereby myelin is destroyed and replaced by plaque

- loss of myelin impairs neuronal function, disrupting transmission of electrical impulses

- clinical presentation depends on area affected (can cause visual impairment, spasticity, paresthesias, decreased coordination, loss of motor function)
What is a synapse? ***
- a point of functional communication between two neurons; a junction between two neurons

- space between the axon of one neuron and the dendrite of the next neuron
What are the three components of a synapse? ***
- presynaptic neuron/membrane
- synaptic cleft
- postsynaptic neuron/membrane
What is a synaptic cleft? ***
a tiny gap between neurons (which do not actually touch) of approximately 20 - 30 nanometers, 10-9 mm, or one millionth of an inch
What is a presynaptic neuron/membrane? ***
- a neuron/membrane whose branches terminate at the synapse

- ends of branches at synaptic region (synaptic knobs/axon terminals) contain vesicles filled with neurotransmitter which, on signal of action potential, are released into the synaptic cleft
What is a postsynaptic neuron/membrane? ***
- a neuron whose receptor begin at the synapse

- receives neurotransmitter at receptor sites (although it may or may not pick it up)
How does neuron to neuron transmission across the synapse function? ***
- an electrical impulse in the form of an action potential travels along the axon of the presynaptic neuron until it reaches the axon terminal

- vesicles in the axon terminal of the presynaptic neuron release the appropriate neurotransmitters into the synaptic cleft

- the neurotransmitters travel across the synaptic cleft to receptor sites specific for that neurotransmitter on the postsynaptic neuron

- the neurotransmitter can be either excitatory or inhibitory depending on the neurotransmitter; can lead to either depolarization or hyperpolarization of postsynaptic membrane

- (electrical... chemical... electrical transmission)
- (action potential... neurotransmitter... action potential)
How does a single neuron handle excitatory and/or inhibitory potentials from thousands of other neurons? ***
the response of the target neuron is determined by the net effect of all the incoming potentials
Describe the effects of the following neurotransmitters: ***
- acetylcholine
- norepinephrine
- dopamine
- serotonin, endorphins, enkephalins
- gamma-aminobutyric acid (GABA)
- excitatory to muscle cells
- excitatory or inhibitory, depending on location
- primarily inhibitory
- primarily inhibitory
- primarily inhibitory
What happens to neurotransmitters not taken up by the postsynaptic membrane? ***
they are:
- immediately reabsorbed by the presynaptic membrane, or
- broken up by enzymes
Is the CNS mainly excitatory or inhibitory? ***

- with hundreds of thousands of interconnecting neurons/synapses … under normal circumstances, majority of these connections must be inhibited…if not, nervous system would overload and short circuit.

For example:
1) strychnine inhibits inhibitory responses (double negative - it stops inhibitory response, thus causes convulsions)
2) Parkinson’s is due to lack of inhibitory NT dopamine (rigidity).
How does neuron to muscle cell transmission of action potentials function? ***
- axon of one motor neuron branches hundreds of times on hundreds of individual muscle cells/fibers of a muscle

- each axonal branch innervates a single muscle cell

- action potential arrives at the presynaptic membrane and stimulates release of neurotransmitter (acetylcholine--ACh)

- the neurotransmitter crosses the synapse to the postsynaptic membrane of the muscle fiber and attaches to ACh receptor sites

- muscle fiber membrane depolarizes and fires an action potential to muscle fiber = contraction of muscle fiber

- all muscle fibers innervated by that one neuron will contract at once = all or none response (all acting as part of the motor unit)
What is a motor unit? ***
a single motor axon/alpha motor neuron and all the muscle fibers (cells) it innervates
What is the neuromuscular junction? ***
the synaptic region between the axonal presynaptic membrane and the muscle fiber
What is the motor end plate? ***
a specialized area of muscle post-synaptic membrane and muscle fiber
List some examples/causes of neuromuscular junction dysfunction secondary to ACh reception dysfunction. ***
- curare (South American vegetable extract) used on hunting darts to paralyze animals; competes with Ach for receptors on postsynaptic membrane; no muscle contractions... can’t breathe... death

- Myasthenia Gravis - disease wherein body produce antibodies which cover Ach receptor sites on postsynaptic membrane … rapidly occurring muscle weakness with activity
Name some commonly used medications that inhibit excessive stimuli. ***
- mehylpenidate hydrochloride (Ritalin) - treatment of attention deficit disorders in children > 6 years old, also symptomatic management of narcolepsy

- clonidine (Catapres) - management of mild to moderate hypertension; either used alone or in combination with other antihypertensive

- bupropion (Wellbutrin) - treatment of depression

- buspirone hydrochloride (BuSpar) - management of anxiety
What is neural integration? ***
- process of sorting, interpreting, and integrating incoming signals and determining an appropriate response

- occurs at the neuronal cell body level

- 90% of neuronal cell bodies are in CNS (brain and spinal cord)

- therefore, CNS is the integration center for the nervous system.
Since the majority of neuronal cell bodies are in the CNS, the CNS is the ______ center for the nervous system. ***
Ninety percent of neuronal cell bodies are located in the ____. ***
CNS (brain and spinal cord)
Describe the external anatomy of the spinal cord. ***
- located in the vertebral canal, surrounded by CSF

- approx. 42-45 cm long (1.5ft); 2/3 length of vertebral column; terminates at approximately L1

- slender cylinder slightly less than 1in. diameter; width varies with slight expansions in Cx (C3-T2) and Lx (L1-S3) regions due to plexuses, origins of nerves and UE and LE at these regions and larger numbers of cell bodies

- continuous with brain stem (medulla oblongata (inside foramen magnum)

- tapers to conus medullaris caudally (inferiorly); below conus medullaris, lumbar and sacral spinal roots descend in a bundle and exit at respective vertebral segmental levels; bundle of spinal nerves is called the cauda equina

- divided into approximately 30 segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and ? coccygeal)
The terminal end of the spinal cord is called the ______ _____. ***
- conus medullaris (at around L1)

- composed of sacral spinal segments
Below the conus medullaris, the bundle of lumbar and sacral spinal roots is called the _____ _____. ***
- cauda equina

- comprised of nerve roots for spinal nerves L2 through S5
The terminal thread that attaches the conus medullaris to the coccyx is called the _____ _______. ***
filum terminale
How are the segments of the spinal cord divided? ***
there is no definitive dividing line, rather a blending of segments
How many spinal nerves are there? ***
at each segmental level are a pair of exiting spinal nerves (31 pairs)
How do the spinal cord segments correspond to the vertebral segments? ***
spinal cord segments do not necessarily correspond to vertebral segments
What structures divide the spinal cord into right and left halves? ***
- anterior median fissure (deep fold containing blood vessels)

- posterior median sulcus
List the membranes surrounding the spinal cord. ***
- same three membranes (meninges) that surround the brain, as they are continuous

- externally to internally:
---- dura mater
---- arachnoid (mater)
---- pia mater
What is the dura mater of the spinal cord? ***
- tough outer membrane

- outer layer attaches to bony vertebral column, inner layer forms a dural sac around spinal cord
What is the arachnoid of the spinal cord? ***
- middle layer closely associated with dura

- thin, transparent, CSF circulates in subarachnoid space
In which space does the CSF circulate around the outside of the spinal cord? ***

(also, to a degree in the central canal, although most of this closes off by adulthood--still may be some at the cervical level)
What is the pia mater of the spinal cord? ***
the innermost layer that closely surrounds the spinal cord
What can extradural, intradural, or epidural masses (tumors, infections, hematomas) cause within the vertebral column? ***
displacement of, or abnormal pressure on the spinal cord
By which vessels is the spinal cord vascularized? ***
arterial circulation:
- subclavian artery (branch of aorta)
- vertebral artery--ascends to brain and descends to spinal cord, and splits into:
---- anterior spinal artery and
---- posterior spinal artery, both of which have many branches around the entire spinal cord, forming a ring of arteries (arterial corona)

venous drainage:
- veins located in the epidural and subarachnoid spaces ultimately drain into the venae cavae
What is the arterial corona of the spinal cord? ***
- a ring of arteries that surrounds the spinal cord

- formed by the split of the vertebral artery into the anterior and posterior spinal arteries and their many branches
What are the clinical implications of impaired circulation to the spinal cord? ***
- occlusion of artery (thrombus) can deprive nervous tissue of blood supply and result in cell death and SC damage

- arterial rupture (hemorrhage) can result in epidural/intradural hematomas and pressure onspinal cord with possible cell death; more common in elderly with hyperextension injuries (anterior spinal artery)
What structures comprise the spinal nerves? ***
a ventral root and a dorsal root comprise each spinal nerve
How many spinal nerves are there? ***
31 pairs
Where do the spinal roots exit the vertebral column? ***
at the intervertebral foramina
Describe the dorsal root of the spinal cord. ***
- contains axonal fibers which are transmitting sensory (afferent) information from the somatic and visceral (autonomic) systems

- conveys sensory information from skin, joints, muscles, and viscera

- each dorsal root contains a dorsal root ganglia (DRG) which contains cell bodies of the sensory axons from the periphery

- roots join in vertebral canal and pass out of it via intervertebral foramen
What is a dorsal root ganglion? ***
a nodule on a dorsal root that contains cell bodies of neurons in afferent spinal nerves
Once the dorsal and ventral nerve roots pass through the intervertebral foramen they merge to form spinal nerves which convey.... ***
both sensory (afferent) and motor (efferent) information
Shortly after the dorsal and ventral roots merge to form the spinal nerve, the spinal nerve splits into.... ***
two primary branches (rami)
What portions of the body do the anterior rami innervate? ***
- limbs
- anterior/lateral trunk
- branch to ANS

- intercostal muscles
- muscles and skin in the extremities
What portions of the body do the posterior rami innervate? ***
posterior trunk

- paravertebral muscles
- posterior aspects of the vertebrae, and the
- overlying skin
Describe the sensory and motor functions of the spinal nerve. ***
(see picture)

- vertical dotted line indicates division between CNS and PNS
- blue spiral in muscle indicates muscle spindle receptor
- blue triangle in muscle indicates Golgi tendon organ
- red "V"s indicate motor endings in muscles
Describe a dermatome. ***
(see picture)

- region of skin innervated by afferent nerve fibers of a single spinal nerve

- lesions at any particular spinal nerve level result in sensory impairment along the dermatomal region
(e.g., C6 spinal nerve compression – sensory deficits to radial forearm/thumb; L5 spinal nerve compression – sensory deficits from anterior/lateral leg to dorsum of foot)

* due to overlapping of dermatomes the areas of innervation tend to vary by author
What is a myotome? ***
- a group of muscles partially innervated by a single spinal nerve (efferent nerve fibers)

(e.g., myotome for C5: scapular muscles, deltoid
C6: elbow flexors, wrist extensors
L2: hip flexors
L3: knee extensors
S1: hip extensors, knee flexors, plantar flexors)
Dermatomes are ______ and myotomes are _______. ***

(sensory or motor)
- sensory/afferent

- motor/efferent
A lesion of a single spinal nerve is usually associated with _____ ______ but not paralysis. ***
muscle weakness (paresis) because the system of innervation has some inherent redundancy

(e.g., L3 spinal nerve compression = weakness of quadriceps, but L2 and L4 can ensure some function remains)
How many spinal nerves make up a dermatome? ***
A lesion of a spinal nerve of a particular dermatome causes ______ impairment. ***
What muscle group(s) does the C6 myotome innervate? ***
- elbow flexors

- wrist extensors
What muscle group(s) does the L2 myotome innervate? ***
hip flexors
What muscle group(s) does the L3 myotome innervate? ***
knee extensors
What muscle group(s) does the S1 myotome innervate? ***
- hip extensors
- knee flexors
- plantar flexors
What muscle group(s) does the C5 myotome innervate? ***
- scapular muscles

- deltoid
Describe the internal anatomy of the spinal cord. ***
longitudinal columns of gray (central) and white matter throughout length of spinal cord
Describe the central gray matter of the spinal cord. ***
- cell bodies -- shaped like a butterfly (or letter "H") in most spinal cord areas (remember the gray matter is masses of cell bodies)

- anterior (ventral) horn -- contains lower motor neuronal cell bodies (alpha and gamma motor neurons); axons exit through ventral root

- (intermedio)lateral horn -- present between T1 and L2 levels; neurons for ANS--specifically cell bodies for preganglionic sympatheic neurons; axons exit through ventral root; responsible for processing autonomic information

- posterior (dorsal) horn -- sensory neuronal cell bodies synapsing with DRG axons in dorsal root

- central gray matter is laminated (layers of nerve cells) with specific types of cell bodies in certain layers (see picture)
---- laminae I - VII primarily sensory neuron cell bodies
---- laminae VIII & IX primarily motor neuron cell bodies
The anterior and posterior gray matter horns are larger in the cervical and lumbar regions of the spinal cord due to.... ***
innervation of the UE and LE
Describe the peripheral white matter of the spinal cord. ***
(see picture)

- peripheral bundles of axons (myelinated and unmyelinated) which surround central gray horn areas

- ascending tracts transmit sensory information to brain from PNS (afferent info)

- descending tracts transmit motor information from brain to PNS (efferent info)

- specific bundles (tracts/columns) have similar origins and destinations, carry common info, and have common functions
How are the tracts/bundles of peripheral white matter organized? ***
- the majority of tracts/bundles exhibit somatotopic* organization with fibers arranged in an orderly fashion from medial to lateral (usually, UE more medially, LE more laterally located)

* point-for-point correspondence of an area of the body to a specific point on the central nervous system (like the homunculus)
Describe the corticospinal tract. ***
(see picture)

- descending motor (efferent) tract/primary motor tract
- pyramidal system (crosses in brain stem)

- transmits motor information from cerebral cortex (primary and premotor cortices) to spinal cord
- main tract for nearly all volitional muscle activity/skilled movements

- monosynaptic (at anterior horn cells)
How is the corticospinal tract referred to in the brain stem with respect to cranial nerves? ***
corticobulbar tract
Trace the descending path of a motor response along the pyramidal motor system's corticospinal tract.

(Need to be able to do this for the test!!) ***
- from neuronal cell bodies in cerebral cortex (gray matter) via myelinated fibers to the
- brainstem, then
- pyramidal decussation at the medulla oblongata (where 80-90% of fibers cross to the contralateral side—the other 10-20% remain in the medial corticospinal tract), then
- down through the spinal cord in the lateral column, where
- at each spinal cord level (segment), designated axons enter gray matter of ventral (anterior) horn and synapse on anterior horn cells with

- consisting of alpha motor neurons (for muscle fibers) and gamma motor neurons (for muscle spindles)
- then the efferent axons exit the spinal cord via the ventral root,
- pass through the spinal nerve,
- into the plexus
- via the peripheral nerve
- to the muscle
What is the result of a lesion at any point along the corticospinal tract? ***
loss of motor response below the level of the lesion

(so if the lesion is above the medulla oblongata, the effect would be seen on the opposite side)
What would be the result of a lesion at a point on the corticospinal tract above the medulla oblongata? ***
loss of motor response on the contralateral side
What is the Nagi model used to describe?
the relationship between health and function
Do impairments necessarily result in functional limitations or disabilities?
no, they may or may not

if someone is still able to perform ADLs and meet their age-specific expectations there is no functional limitation or disability

progression is not inevitable either
What is "buffering the disablement process"?
preventing impairment, functional limitation, or disability by identifying disablement risk factors that may impede patient functioning and interrupting the progression
What is the Guide's definition of function?
- activities identified by an individual as essential to support physical, social, and psychological well-being and to create a personal sense of meaningful living

- it is related to age-specific roles in a given social contexts and physical environment
What factors define an individual's functional performance?
personal characteristics such as:
- physical ability
- emotional status
- cognitive ability
- environment in which person functions
- social expectations placed on the person's performance by family, the community, or society in general
What is a handicap?
the societal disadvantage of disability
Besides personal characteristics, environment, and social expectations, what else can affect the disablement process?
individual factors such as:
- congenital disorders
- genetic predisposition to disease
- demographics (age, sex, educational level, socioeconomic status)
- comorbidities
- lifestyle choices
- health habits
- environmental factors (including access to medical and rehab care and physical and social environments)
What should the PT consider before delegating interventions to the PTA?
- knowledge, skills, and abilities of the PTA

- whether the intervention requires immediate and continuous examination and evaluation of the patient (per APTA, these interventions are to be performed exclusively by the PT)
- patient's condition (stability, acuity, criticality and complexity)

- practice setting
- type of intervention
- patient's probable outcome
- restrictions imposed by patient's insurance
When may interventions for pediatric patients be delegated to PTAs? When may they not?
- under the direction and supervision of a PT

- when the child is physiologically unstable, or the child's condition requires multiple adjustments of sequences and procedures due to rapidly changing physiologic status and/or response to treatment
What are the PT responsibilities in the examination phase?
- obtain patient history
- perform systems review
- select and administer tests and measures
- identify issues that require consultation with or referral to another provider
What are the PT responsibilities in the evaluation phase?
- use data from examination to make clinical judgments
- identify issues that require consultation with or referral to another provider
What are the PT responsibilities in the diagnosis phase?
- interpret evaluation/examination data
- organize data into clusters, syndromes, categories
- determine prognosis and POC
- plan the most appropriate intervention strategies
What are the PT responsibilities in the prognosis phase?
- determine level of optimal improvement expected from interventions
- assess amount of time required to reach optimal improvement
- document POC specifying interventions to be used, timing, and frequency
What are the PT responsibilities in the intervention phase?
- apply purposeful and skilled interaction with patient/client and, if appropriate, with other individuals involved in patient's/client's care
- use various physical therapy methods to produce changes in patient's/client's condition consistent with the diagnosis/prognosis
- assess the patient/client for new clinical findings or lack of progress
- reexamine the patient's/client's status to determine changes and modify or redirect intervention
The brain, brain stem and spinal cord are composed of two basic types of nerve cells called _______ and _____.
- neurons

- neuroglia
What are the three subtypes of neurons?
- afferent neurons (sensory)
- interneurons (connectors)
- efferent neurons (motor)
What is another name for a neuronal cell body?
Name of the interface between:
- neuron and neuron
- neuron and muscle fiber
- neuron and gland
- synapse
- neuromuscular junction
- neuroglandular junction
Which neurotransmitter is used by all neurons that synapse with muscle fibers?
acetylcholine (ACh)
Myelinated axons are bundled together within the CNS to form ______ _____.
fiber tracts
What is the surface of the cerebrum called?
cerebral cortex
What are the depressions (valleys) of the cerebral cortex called? The ridges?
- sulcus (pl. sulci)

- gyrus (pl. gyri)
What is the purpose of the gyri and sulci of the cerebral cortex?
they increase the surface area of the cerebrum without requiring an increase in the size of the brain
List the layers and spaces of the meninges, outermost to innermost.
- epidural space
- dura mater
- subdural space
- arachnoid
- subarachnoid space
- pia mater
What is the "sidedness" of brain function called?
- hemispheric specialization
- lateralization
The frontal lobe is frequently referred to as the ______ ______ _______.
primary motor cortex
For what functions is the frontal lobe responsible?
- voluntary control of complex motor activities
- cognitive functions (judgment, attention, awareness, abstract thought, mood, aggression)

- Broca's area - principal motor region for speech
(left hemisphere - plans movements of the mouth,
right hemisphere - nonverbals, such as gestures and adjustment of tone)

(motor input is mapped via the motor homunculus)
For what functions is the parietal lobe responsible?
- primary sensory cortex
- perception (attaching meaning to sensory information)

(sensory input is mapped via the sensory homunculus)
For what functions is the temporal lobe responsible?
- primary auditory cortex
- visual perception
- musical discrimination
- long-term memory

(Wernicke's area allows hearing and comprehension of spoken language)
For what functions is the occipital lobe responsible?
- primary visual cortex
- organizes, integrates, and interprets visual information
What are association areas within the brain?
regions within the parietal, temporal, and occipital lobes that horizontally link different parts of the cortex

(e.g., sensory association cortex integrates and interprets information from all the lobes receiving sensory input and allows individuals to perceive and attach meaning to sensory experiences
What are some additional functions of the association areas?
- personality
- memory
- intelligence (problem solving and comprehension of spatial relationships)
- generation of emotions
The primary motor cortex of the frontal lobe is primarily responsible for....
contralateral voluntary control of upper extremity and facial movement
The premotor area of the frontal lobe is primarily responsible for....
- controlling muscles of the trunk and

- anticipatory postural adjustments
The supplementary motor area of the frontal lobe is primarily responsible for....
- initiation of movement
- orientation of eyes and head
- bilateral, sequential movements
Which hemisphere of the brain is considered the dominant hemisphere in an individual?
- the one responsible for language

- thus, approximately 95% of the population (including all right-handed individuals) are left-hemisphere dominant

(even 50% of left-handed individuals are left-hemisphere dominant)
What are the functions of the left hemisphere of the brain?
verbal/analytic side

- cognitive style --- processing information in a sequential, organized, logical, and linear matter for thorough analysis

- perception/cognition --- language processing and producing for most people (specifically frontal and temporal lobes)

- academic skills --- recognizing and comprehending written words (parietal lobe); mathematical calculations

- motor --- sequencing movements; performing movements and gestures to command

- emotions --- expressing positive emotions
What are the functions of the right hemisphere of the brain?
verbal/artistic side

- cognitive style --- processing information in a simultaneous, holistic, or gestalt manner; grasping overall organization or pattern

- perception/cognition --- processing nonverbal stimuli (environmental sounds, speech intonation, complex shapes and designs); visual-spatial perception; drawing inferences, synthesizing information

- academic skills --- mathematical reasoning and judgment; alignment of numerals in calculations

- motor --- sustaining a movement or posture

- emotions --- expressing negative emotions; perceiving emotions
Common impairments seen in patients with left hemispheric injury include:
- inability to plan motor tasks (apraxia)
- difficulty initiating, sequencing, and processing tasks
- difficulty producing or comprehending speech
- perseveration of speech or motor behaviors
- anxiousness
Common impairments seen in patients with right hemispheric injury include:
- poor judgment
- unrealistic expectations
- denial of disability or deficits
- disturbances in body image
- irritability
- lethargy
Describe the structure and function of the internal capsule.
- an area of white matter in the brain that contains both ascending and descending axons (sort of looks like the stalk of a cauliflower floret)

- consists of axonal fibers that run between the cerebral cortex and the pyramids of the medulla
What sequelae can a lesion within the internal capsule cause?
contralateral loss of voluntary movement and conscious somatosensation
What structures comprise the diencephalon?
- thalamus
- hypothalamus

(the lecture notes include epithalamus and subthalamus as well)
What is the function of the thalamus?
- central relay station

- channels sensory impulses (except smell) traveling upward from the rest of the body to the proper areas of the cerebral cortex for processing, including to association areas

- channels motor information from the basal ganglia and cerebellum to the correct motor region
What is the function of the hypothalamus?
- regulation of homeostasis via regulation of automatic functions (e.g., thirst, hunger, digestion, body temperature, blood pressure, sexual activity, and sleep-wake cycles

- integrates functions of the endocrine system and the autonomic nervous system through regulation of the pituitary gland and its release of hormones
What is the function of the hypothalamus?
- regulation of homeostasis via regulation of automatic functions (e.g., thirst, hunger, digestion, body temperature, blood pressure, sexual activity, and sleep-wake cycles

- integrates functions of the endocrine system and the autonomic nervous system through regulation of the pituitary gland and its release of hormones
What is the function of the basal ganglia?
- influence the motor planning areas of the cerebral cortex through various motor circuits

- regulation of posture and muscle tone
- control of volitional and automatic movement
- some cognitive function (caudate nucleus portion)
What signs do Parkinson's patients exhibit?
- bradykinesia (slowness initiating movement)
- akinesia (difficulty initiating movement)
- tremors
- rigidity
- postural instability

(due to death of cells in the substantia nigra, which produces dopamine)
What is the structure and function of the limbic system?
- deep brain structures in the diencephalon and cortex that includes parts of the thalamus and hypothalamus and a portion of the frontal and temporal lobes

- controls emotional reactions such as rage and fear (hypothalamus)
- guides emotions that regulate behavior
- learning and memory
- controls memory, pain, pleasure, rage, affection, sexual interest, fear, and sorrow
What is the function of the midbrain?
- connects diencephalon to the pons

- acts as relay station for tracts passing between cerebrum and spinal cord or cerebellum

- houses reflex centers for visual, auditory, and tactile responses
What is the function of the pons?
- contains bundles of axons that travel between cerebellum and rest of CNS
- functions with medulla to regulate breathing rate

- contains reflex centers that assist with orientation of head in response to visual and auditory stimulation

- cranial nerve nuclei can also be found within the pons, specifically CN V-VIII for motor and sensory information to/from the face
What is the function of the medulla?
- extension of the spinal cord containing fiber tracts that run through the spinal cord

- contains motor and sensory nuclei for the neck and mouth regions

- contains control center for heart and respiration rate

- contains reflex centers for vomiting, sneezing, and swallowing
What is the function of the reticular activating system?
- within the brain stem; extends vertically throughout its length
- maintains and adjusts individual's level of arousal, including sleep-wake cycles

- facilitates voluntary and autonomic motor responses necessary for certain self-regulating, homeostatic functions
- involved in modulation of muscle tone throughout the body
Name the two primary ascending sensory tracts present in the white matter of the spinal cord.
- dorsal (posterior) columns

- spinothalmic tract
What sensory information does the dorsal (posterior) column carry?
- proprioception
- vibration
- 2-point discrimination
- deep touch
What sensory information does the spinothalmic tract carry?
- pain

- temperature sensation
Structure and function of the rubrospinal tract
- originates in red nucleus of mid-brain
- terminates in anterior horn
- synapses in anterior horn with LMN that primarily innervate the UEs

- fibers facilitate flexor motor neurons, inhibit extensor motor neurons
- proximal muscles primarily affected, but some influence over more distal groups

- thought to assist in the correction of movement errors
Function of lateral vestibulospinal tract
- assists in postural adjustments through facilitation of proximal extensor muscles
Function of medial vestibulospinal tract
regulation of muscle tone in the neck and upper back
Function of medial reticulospinal tract
facilitates limb extensors
Function of lateral reticulospinal tract
facilitates flexors and inhibits extensor muscle activity
Function of the tectospinal tract
provides for orientation of the head toward a sound or a moving object
What is an anterior horn cell?
- large neuron in the gray matter of the spinal cord that sends out axons through ventral spinal roots

- eventually these axons become peripheral nerves and innervate muscle fibers
Describe an alpha motor neuron.
- type of anterior horn cell that innervates skeletal muscle

- due to axonal branching, one alpha motor neuron can innervate several muscle fibers

- the alpha motor neuron and all the muscle fibers it innervates comprise a motor unit
Describe a gamma motor neuron.
- type of anterior horn cell

- motor neuron that transmits impulses to intrafusal fibers of the muscle spindle
What is a muscle spindle?
- sensory organ found in skeletal muscle

- comprised of motor and sensory endings and muscle fibers

- responds to stretch, thus provides feedback to CNS regarding the muscle's length
An important fact about stretch or deep tendon reflexes is that their activation and subsequent motor response can occur without....
higher cortical influence

(cerebral cortex is not involved in the reflex arc)
Why is it clinically important that the cerebral cortex is not involved in the reflex arc?
because a patient with a spinal cord injury can still exhibit lower extremity deep tendon reflexes despite lower extremity paralysis
Describe the somatic component of the PNS (the SNS).
- voluntary, conscious control
- reactions to outside stimulation
- skeletal muscle contraction by way of 31 pairs of spinal nerves
- also 12 pairs of cranial nerves, which are sensory and motor (innervate SCM and trapezius)
Describe the autonomic component of the PNS (the ANS).
- involuntary
- innervates glands, smooth (visceral) muscle, and cardiac muscle
- primary function is to maintain homeostasis
- regulation of digestion, circulation, and cardiac muscle contraction
Where are the cranial nerves located?
in the brain stem

(but they are a part of the PNS!!)
How are the spinal nerves numbered, and how do they correlate to the vertebrae?
- C1 through C7 exit above the same numbered vertebra

- C8 exits above T1 (or below C7)

- thereafter, the nerves exit below the vertebra (e.g., L3 spinal nerve exits below L3 vertebra)
Once through the intervertebral foramina, the spinal nerves...
- divide into two primary rami

- this division represents the beginning of the PNS
Which spinal nerves form plexuses?
the anterior primary rami of the
- cervical (C1-C4)
- brachial (C5-T1)
- lumbosacral (L1-S3)

- no plexuses in the thoracic
Describe the cervical plexus.
- comprised of anterior primary rami of the C1-C4 spinal nerves

- primarily innervate
---- deep muscles of neck,
---- superficial anterior neck muscles,
---- levator scapulae,
---- portions of the trapezius and SCM
Describe the phrenic nerve.
- within cervical plexus
- formed from branches of C3-C5
- innervates the diaphragm
- only motor and main sensory nerve for this muscle
Describe the brachial plexus.
- comprised of anterior primary rami of the C5-T1 spinal nerves

- divides and comes together several times, providing redundant motor and sensory innervation from more than one spinal nerve root level

- 5 primary nerves:
---- musculocutaneous - forearm flexors
---- axillary
---- radial - elbow, wrist, and finger extensors
---- median - forearm pronators, wrist and finger flexors, thumb abductors and opposers
---- ulnar - assists median nerve with wrist and finger flexion, abducts/adducts fingers, opposition of 5th finger

- innervates the majority of the UE musculature, except
---- medial pectoral nerve (C8) - pectoralis muscles
---- subscapular nerve (C5-C6) - subscapularis
---- thoracodorsal nerve (C7) - latissimus dorsi
Describe the lumbosacral plexus.
- innervate LE musculature
- comprised of the anterior primary rami of the L1-S3 spinal nerves
- does not undergo the same separation and reuniting as does the brachial plexus

- innervates muscles of
---- thigh
---- lower leg
---- foot

- 8 roots that form 6 primary peripheral nerves
---- obturator
---- femoral
---- superior gluteal
---- inferior gluteal
---- common peroneal
---- tibial
(common peroneal and tibial form sciatic nerve)
Describe the motor fibers of a peripheral nerve.
- large cell body with multiple branched dendrites (multipolar) located within anterior horn of spinal cord

- long axon that exits the anterior horn through the white matter and bundles with other similar axons in the ventral root in the intervertebral foramen

- becomes part of a peripheral nerve and innervates a motor end plate in a muscle
Describe the sensory fibers of a peripheral nerve and the routing of a sensory signal.
- dendrite originates in the skin, muscle tendon, or golgi tendon organ

- action potential travels from skin/tendon/GTO to cell body in the dorsal root ganglion within the intervertebral foramen for processing

- action potential continues from cell body through axon and into the dorsal root of the spinal nerve

- then passes into the gray matter of the spinal cord through the dorsal horn

- may then synapse with interneuron, relay to motor neuron, and constitute a reflex arc, or decussate to the other side of the gray matter, exit the gray matter, enter the white matter fiber tracts and ascend to a different level in the spinal cord or brain stem
Name the functions of the ANS.
regulation of
- circulation
- respiration
- digestion
- metabolism
- secretion
- body temperature
- reproduction
Where is the control center for the ANS?
- hypothalamus
- brain stem
The ANS is composed of motor neurons located within spinal nerves that innervate....
- smooth muscle
- cardiac muscle
- glands

(a.k.a. effectors or target organs)
Divisions of the ANS
- sympathetic nervous system

- parasympathetic nervous system
Which division of the ANS innervates internal organs, the sympathetic, or parasympathetic?
- both

- they affect the organs in basically antagonistic ways
Describe the neural pathway of the sympathetic and parasympathetic divisions of the ANS.
- two-neuron pathway (presynaptic and postsynaptic)

- one-ganglion impulse conduction between the ganglia
How do the sympathetic and parasympathetic nervous systems achieve autoregulation?
- by integrating information from peripheral afferents with information from receptors within the CNS

- the two-neuron pathway (preganglionic and postganglionic neurons) provides the connection from the CNS to the autonomic effector organs

- cell bodies of the preganglionic neurons are located within the brain or spinal cord, and the myelinated axons exit the CNS and synapse with postganglionic cell bodies

- unmyelinated axons from postganglionic neurons innervate the effector organs
The sympathetic fibers of the ANS arise from which vertebral levels?
- thoracic and lumbar

- motor functions of the sympathetic nervous system take one of 5 paths:
---- via paravertebral ganglionic chain to cervical or sacral levels
---- directly to tissue
---- to a thoracic organ
---- to a collateral ganglion enroute to an abdominopelvic organ
---- to adrenal medulla
The sympathetic nervous system evokes the "______ or ______" response, while the parasympathetic nervous system evokes the "_______ and ______" response.
- fight or flight

- rest and digest
Activation of the sympathetic nervous system causes what reaction in the cardiopulmonary system?
- vasoconstriction of blood vessels, increasing BP and pulse rate

- blood flow diverted to muscles from GI tract
From where does the parasympathetic nervous system receive its information?
from the brain stem, specifically cranial nerves:
- III - oculomotor
- VII - facial
- IX - glossopharyngeal
- X - vagus

- and from lower sacral segments of the spinal cord
Motor fibers of the vagus nerve innervate:
- myocardium
- smooth muscles of lungs
- smooth muscles of digestive tract
Parasympathetic nervous system activation of the vagus nerve can cause:
- bradycardia
- decreased force of cardiac muscle contraction
- bronchoconstriction
- increased mucus production
- increased peristalsis
- increased glandular secretion
Parasympathetic nervous system activation of the lower sacral segments can cause:
- emptying of bowels
- emptying of bladder
- arousal of sexual organs
Which neurotransmitters are used at the preganglionic synapses for both the sympathetic and parasympathetic nervous systems?

At the sympathetic and parasympathetic postganglionic synapses with effector cells?
- both the sympathetic and parasympathetic nervous systems use the neurotransmitter acetylcholine at the preganglionic synapse

- at the postganglionic synapse, the parasympathetic nervous system uses the neurotransmitter acetylcholine, however, the sympathetic nervous system uses norepinephrine (noradrenaline) to fuel "fight or flight"
Activation of the parasympathetic nervous system causes what cardiovascular effects?
- dilation of arterioles; vasodilation

- decreased heart rate
- lowered blood pressure
- return of normal GI activity
How does the CNS exert influence over the ANS?
- via hypothalamus which regulates functions such as digestion

- via the medulla, which controls heart and respiration rates
Why is it necessary that the neurons of the brain receive a constant supply of blood?
- the neurons in the brain are unable to carry out glycolysis or store glycogen

- they need a continuous supply of glucose and oxygen

- the blood is the only way to obtain the fuel the brain needs
All arteries to the brain arise from the ______ ____.
aortic arch
Which cerebral artery is the largest and most often occluded?
the middle cerebral artery (which supplies the lateral surface as well as the deep frontal and parietal lobes of the brain with blood)
Which vessels comprise the anterior circulation to the brain?
- middle cerebral artery
- anterior cerebral artery
Posterior circulation to the brain is composed of the two vertebral arteries, which are branches of the _______.
subclavian artery
The vertebral arteries supply blood to the ______ and ______, and unite to form the ______ ______.
- brain stem
- cerebellum

- basilar artery
The basilar artery supplies the _____ ____ and the medial portion of the _______ and ________ lobes.
- brain stem
- temporal
- occipital
What vessels form the Circle of Willis?
- anterior cerebral artery (left and right)
- anterior communicating artery

- internal carotid artery (left and right)

- posterior cerebral artery (left and right)
- posterior communicating artery (left and right)

- the basilar artery and middle cerebral arteries which supply the brain are also considered part of the circle
What is the benefit of the Circle of Willis?
- its design ensures that failure or occlusion of one cerebral artery does not critically decrease blood flow to that region

- the occlusion can be circumvented or bypassed to meet the nutritional and metabolic needs of cerebral tissue
What are the aftereffects of arterial obstruction of sufficient duration within the CNS?
- cell and tissue death within minutes
- neurons that die due to oxygen deprivation cannot regenerate
- neurons in the vicinity of damage are susceptible to injury secondary to release of glutamate, an excitatory neurotransmitter
What are glutamate's effects within the nervous system?
- it is an excitatory neurotransmitter

- at normal levels it assists with CNS functions
- at higher levels, however, it can be toxic to neurons and can promote neuronal death

- it also facilitates calcium release, which ultimately produces a cascade of events, including liberation of calcium-dependent digestive enzymes, cellular edema, cell injury, and cell death
How long does it take for changes within oxygen-deprived neurons to manifest? What changes occur? What are the sequelae?
- no changes evident for 12-24 hours
- by 24-36 hours the damaged area becomes soft and edematous

- liquifaction and cavitation begin, and the area of necrotic tissue is eventually converted into a cyst
- in time, the infarct retracts and the cystic cavity will be surrounded by a glial scar

- the damaged neurons will not be replaced, and the original function of the area will be lost

- nearby undamaged axons demonstrate collateral sprouting 4-5 days after injury
- these sprouts replace the damaged synaptic area, increasing input to other neurons
- although collateral sprouts do not replace original circuits, they do develop from systems most closely associated with the injured area
What are the most common causes of PNS nerve injuries?
- usually from other than vascular compromise

common causes include:
- stretching
- laceration
- compression
- traction
- disease
- chemical toxicity
- nutritional deficiency
How does the response to injury of nerves of the PNS differ from that of nerves of the CNS?
- if the cell body is destroyed, regeneration is not possible and wallerian degeneration occurs

- if the damage to the peripheral nerve is not too significant and occurs only to the axon, regeneration is possible

- axonal sprouting from the proximal end of the damaged axon can occur

- to have a return of function, the axon must grow and reinnervate the appropriate muscle; failure to do so results in degeneration of the axonal sprout
Describe wallerian degeneration.
when the cell body of a PNS nerve is destroyed, regeneration is not possible, but if the axon is severed:
- the axon terminal degenerates
- the axon undergoes necrosis distal to the site of injury
- the myelin sheath begins to pull away, breaks down, and forms debris
- cell body undergoes metabolic changes
- presynaptic terminals retract from dying cell body
- postsynaptic cells degenerate
- the Schwann cells phagoctize the area
How fast can a damaged PNS axon regrow?
1.0 mm per day, depending on size of the nerve fiber
Upon what does the rate of recovery from a peripheral nerve injury depend?
- age of patient

- distance between lesion and destination of the regenerating nerve fibers
Describe an upper motor neuron injury.
- damage to the corticospinal tract between the frontal lobe and the spinal cord

clinical signs include:
- spasticity (increased resistance to passive stretch)
- hyperreflexia
- presence of Babinski sign
- possible clonus (repetitive stretch reflex that is elicited by passive dorsiflexion of the ankle or passive extension of the wrist)
Describe a lower motor neuron injury.
injury to:
- the anterior horn cell
- motor nerve cells of brain stem
- spinal root
- spinal nerve

clinical findings include:
- flaccidity
- marked muscle atrophy
- muscle fasciculations
- hyporeflexia
What are the functions of the other descending motor tracts (extrapyramidal system)? ***
- efferent tracts originating from location other than precentral gyrus of cortex (subcortical motor areas,) primarily different areas of the brainstem

- primarily involved with quality of motor function, equilibrium reflexes, spinal reflexes
Name two efferent extrapyramidal descending tracts. ***
- vestibulospinal

- rubrospinal
Describe the vestibulospinal efferent extrapyramidal descending tract. ***
vestibular nuclei in brainstem to anterior horn cells to extensor muscles

- destination: anterior horn (alpha and gamma motor neurons)
Describe the rubrospinal efferent extrapyramidal descending tract. ***
- red nucleus in brainstem to anterior horn cells

- destination: anterior horn (alpha and gamma motor neurons)
What is the function of the spinothalamic tract? ***
- ascending (afferent/sensory) tract

- transmites pain, temperaure, touch (crudely localized, e.g., "leg"--general area
Describe the route of the spinothalamic tract. ***

(Be able to do this from memory for the test!!)
- cutaneous receptors to
- dorsal root ganglion, to
- posterior (dorsal) horn, then
- extensive synapses with interneurons (at spinal cord level as well as suprasegmentally--divergence) for possible reflex responses

- information being transmitted to the brain crosses (within 2-3 segments) to contralateral spinal cord and travels cranially as the ventro-lateral spinothalamic tract
- tract (and information) ascends to thalamus, which acts as a relay station, then the signal
- travels on to cerebral cortex
What is the result of a lesion to the spinothalamic tract? ****
- loss of pain/temperature/crude touch sensation in opposite side of body below the level of the injury
Describe the lemniscal system of the dorsal columns. ***
- fasciculus gracilis
- fasciculus cuneatus

- conscious proprioception
- discriminative touch, (2 pt discrimination—how many fingers you are being poked with, etc.)
- stereognosis—know what you’re touching, recognize by feeling)
- vibration

- receptors in skin, joints, tendons (GTO), muscles

- receptors located cutaneously and deep in joint/tendons/muscles
- via dorsal root ganglion
- spinal cord
- travels ipsilaterally entire cord in dorsal columns
- brainstem
- crosses to other side
- postcentral gyrus
What is the fasiculus cuneatus? ***
lateral dorsal column that receives information from arms
What is the fasiculus gracilis? ***
medial dorsal column that receives information from legs
What is caused by a lesion on the posterior (dorsal) columns? ***
- inability to recognize common objects by touch
- loss of vibratory sensation

(on ipsilateral side below level of lesion)
What is the function of the spinocerebellar tract? ***
unconscious movement and position sensation
Where are the receptors for the spinocerebellar tract? ***
deep in joints, tendons, muscles
Describe the route of the spinocerebellar tract. ***
- receptors located deep in joints/tendons/muscles, to
- dorsal root ganglion
- dorsal root,
- posterior horn of spinal cord
- travels ipsilaterally in lateral column
- to ipsilateral cerebellum
What functions does the cerebellum carry out upon receiving information via the spinocerebellar tract? ***
- processes input with other incoming information to control:
--- motor activity
--- equilibrium
--- muscle tone at the unconscious (automatic) level
What occurs if there is a lesion in the spinocerebellar tract? ***
- poorly controlled movments
- poor equilibrium responses
- abnormal postural sway with eyes shut
List the major motor tracts. ***
- corticospinal tract - main tract for nearly all volitional muscle activity
- corticobulbar tract - how corticospinal tract is referred to in the brain stem with cranial nerves

- vestibulospinal tract - brain stem to anterior horn cells to extensor muscles, maintain balance of body and head
- rubrospinal tract - red nucleus in brain stem to anterior horn cells to flexor muscles; large muscle movement and fine motor control (generally upper limb)
(also reticulospinal and olivospinal)
List the major sensory tracts. ***
- spinothalamic tract - pain, temperature, crudely localized touch
- lemniscal system (dorsal columns--fasciculus cuneatus/arms, fasciculus gracilis/legs, etc) - conscious proprioception, discriminative (2-point) touch, stereognosis, vibration
- spinocerebellar tract - unconsious movement and position sensation
What is a reflex? ***
- a stereotyped involuntary motor response to well-defined stimulus

- not learned--an inborn neural circuitry
What are the three general types of reflexes? ***
- spinal reflexes (spinal cord)
- postural reflexes (brainstem)
- equilibrium reflexes (cortical)
What is a spinal reflex? ***
- reflex occurring at the spinal cord level; does not require supraspinal (cortical) input

- a hardwired response

- requires an intact simple reflex arc:
--- receptor/special sense organ
--- afferent neuron to SC
--- interneuron(s) in SC
--- efferent neuron (AMN) to effector/muscle
(does not travel up the SC)
What are the types of spinal reflexes? ***
- muscle stretch reflexes - quick stretch sensed by muscle spindles
- flexor withdrawal reflex - flexion of body part away from noxious stimulus
- crossed extensor reflex - compensates for flexor withdrawal with opposite limb (e.g., to ensure we don't fall down)
Describe a muscle stretch reflex. ***
myostatic or deep tendon reflexes (DTRs) cause knee, ankle, biceps, and triceps jerk
How is a muscle stretch reflex elicited? ***
1) quick stretch to muscle stimulates special receptors in muscle (muscle spindles)
2) action potentials fired to DRG; posterior horn of spinal cord

3) immediately synapses with motor neurons or interneurons at appropriate segmental level (excitation of agonist muscle; inhibitions of antagonist muscle)
4) resulting in contraction of agonist (muscle which was stretched) and relaxation of antagonist (reciprocal inhibition): antagonist muscle inhibited during activation of agonist muscle)

5) reflex allows for rapid protection of a muscle which is being rapidly stretched
6) common DTRs tested clinically; C5: biceps jerk, C7: triceps jerk, L4; knee jerk, S1: ankle jerk

7) therapeutic considerations: rationale for stretching a muscle slowly and quick stretch to facilitate a muscle contraction
Describe the flexor withdrawal reflex. ***
1) noxious stimulus to cutaneous receptors (UE)
2) fire action potentials to DRG…posterior horn

3) immediately synapse with interneurons at appropriate segmental levels (excitatory polysynaptic potentials (EPSPs) to flexor muscles)
4) resulting in flexion of body part/s away from noxious stimulus (you pull your hand off a hot burner)
Describe the crossed extensor reflex. ***
1) noxious stimulus to cutaneous receptors (UE)
2) fire action potentials to DRG…posterior horn….
3) immediately synapse with interneurons (excitation of flexor muscle/same leg and extensor muscle/opposite leg)
Explain the neural pathways of the withdrawal and crossed extensor reflexes in the picture. ***
- person steps on tack
- sensory information travels to dorsal horn and
---- passes through the gray matter and travels up the spinothalamic tract for processing in the brain
---- synapses with interneuron in gray matter, which synapses with motor neurons at the ventral horn to create a reflex arc to lift foot (withdrawal reflex)
---- travels up to multiple levels (divergence) to further effect withdrawal reflexes and crossed extension reflexes (flexes hip, tenses gluteals and quadriceps to support weight)
What may override spinal reflexes, and when does it happen? ***
- higher cortical function may override spinal reflexes

(e.g., you manage to hang onto a hot cup of coffee for the few seconds it takes to set it down without spilling it)
What happens when spinal reflexes are disrupted by SCI or PNI? ***
- below SCI, spinal reflexes are exaggerated (hyperreflexia) because the reflex arc connections have been interrupted

- at level of PNI, spinal reflexes are lost (hyporeflexia) because the reflex arc connections have been interrupted
How are spinal reflexes graded? ***

0 -
1+ -
2+ -
3+ to 4+ -
- areflexia
- hyporeflexia
- normal
- hyperreflexia
Describe a lower motor neuron. ***
- final common pathway from anterior horn outward

-anterior horn cell (alpha/gamma motor neuron) and axon which transmit efferent info to ventral root of spinal nerve to peripheral nerve to synapse at motor end plate

- “final common pathway” of neuronal impulses from CNS to muscle; primarily corticospinal tract
What are the results of a LMN lesion? ***
- loss of motor commands from motor neuron in spinal cord and
- loss of reflex activity; reflex arc interrupted

1. hypotonicity – decreased resistance to passive stretch; flaccidity
2. hyporeflexia – diminished/absent spinal reflex arc mechanism
3. paralysis/paresis (very weak) – impaired volitional movement
4. rapid and significant mm atrophy/wasting
5. fasiculations and/or fibrillation – palpable/non-palpable twitches of muscle fibers in denervated tracts (circular)
Describe an UMN. ***
motor neuron in cortical region and axon which transmit efferent information to spinal cord/anterior horn cell (motor neuron)
What results from an UMN lesion? ***
- loss of motor commands from CNS and
- inhibition of spinal reflexes by higher brain centers

1. hypertonicity – increased resistance to passive stretch; spasticity/rigidity/clonus
2. hyperreflexia – increased reflex activity response to stimulus
3. paralysis/paresis – loss of volitional movement
4. minimal muscle atrophy secondary to disuse
Describe a complete SC transection. ***
- complete severance of spinal cord
- common with traumatic spinal cord injuries (MVA, diving, etc.)
- can occur at cervical, thoracic, lumbar regions

- complete loss of sensory and motor function below level of lesions
- hypertonicity, hyperreflexia
True or false:
If a patient exhibits hyporeflexia they most likely have a peripheral nerve injury rather than a spinal nerve injury. ***
True or false:
The flexor withdrawal reflex is when the extremity opposite the one that received the stimulus extends. ***
this is the crossed extensor reflex
True or false:
A grade of 2+ indicates normal reflex activity. ***
True or false:
A patient with an upper motor neuron lesion can be expected to exhibit hypertonicity. ***
True or false:
A person with a complete cord transection will experience loss of motor and sensory function below the level of the injury. ***
Describe a central cord lesion of the spinal cord. ***
- damage to central aspect of spinal cord and sparing of peripheral portions
- common with cervical injuries and resultant hemorrhage/nervous tissue necrosis in cervical region

- pictured lesion interrupts fibers crossing to enter spinothalamic tracts and fibers mediating the tendon stretch reflex; if this lesion enlarges, it will also affect the intermediolateral columns (ANS functions) and lateral corticospinal tracts
- sensorimotor impairment of upper extremities, greater in lower extremities because of spatial orientation of fiber tracts (cervical segments are located closer to central gray matter)
- possible hypertonia, hyperreflexia

- depends on how much of cord is involved
Describe a hemisection spinal cord lesion. ***
- damage to one-half (R or L/ant or post) of spinal cord
- common with bullet/stab wounds, spinal cord tumors
What is the resultant sensorimotor impairment from Brown-Sequard syndrome? ***
- sensorimotor impairment below level of lesion as follows:
1. ipsilateral loss of motor function
2. ipsilateral loss of proprioception,
3. contralateral loss of pain, temperature
- possible hypertonicity, hyperreflexia
What is the result of a posterior cord lesion? ***
- damage to dorsal columns
- loss of proprioception sensation from extremities resulting in ataxia (incoordination – can’t sense where extremity is)
- also loss of discriminative touch, steriognosis, sensation of vibration
- sparing of motor function, pain, temperature

- common with tabes dorsalis (tertiary syphilis) AIDS patients, traumatic SCI/tumors (depending on site of lesion)
What is the result of an anterior cord lesion? ***
- damage to ventral aspect of spinal cord
- due to incomplete spinal cord trauma, tumor

- loss of motor function, pain, temperature below level of lesion
- sparing of proprioception below level of lesion
- possible hypertonicity, hyperreflexia
What is spina bifida? ***
- failure of neural tube closure in utero, associated with maldevelopment of vertebrae
- meninges of spinal cord balloon out into a sac overlying the deformed vertebrae

- not a significant problem unless spinal cord herniates into sac (meningomyelocele) resulting in severe sensorimotor impairments below level of lesion
- possible hypertonicity, hyperreflexia
What is Amyotrophic Lateral Sclerosis? ***
(ALS – Lou Gehrig’s Disease)

progressive disease of corticospinal tracts with initial paralysis of UE then LE muscles and progressing to respiratory muscles
What is an HNP and what are its potential effects? ***
Herniated Nucleus Pulposus

- results in pressure on ventral and/or dorsal nerve roots;
- pain/paresthesias in dermatomal distribution for that spinal nerve;
- muscle paresis in myotomal distribution
What is poliomyelitis and what are its effects? ***
- destruction of anterior horn cells due to acute infection

- results in flaccid paralysis, hyporeflexia
- affects LMN
Match the descriptions with the following pathologies: ***

1. destruction of anterior horn cells
2. loss of motor function, pain, temperature below lesion
3. sensorimotor impairment of UE and LE
4. loss of motor function ipsilateral below lesion

a. anterior cord lesion
b. central cord lesion
c. hemisection cord lesion
d. poliomyelitis
- d
- a
- b
- c
Describe the structure and function of the brainstem. ***
- most caudal part of brain, lower end joins spinal cord through foramen magnum
- consists of a central ventricle (4th) surrounded by a core of gray matter, surrounded by white matter (sensory and motor tracts) with various nuclei interspersed
- location centrally for the fourth ventricle which contains cerebrospinal fluid which flows to and from spinal cord

- many features in common with spinal cord
- contains descending and ascending tracts to and from spinal cord (all afferent and efferent tracts pass through here)

- also has features which distinguish it as part of the brain (distinct nuclei)
- compact, diverse functions as relay station for all information moving between spinal cord, cerebellum, and cerebrum

- provides face and neck with sensory and motor innervation via multiple cranial nerves
- provides pathways to and from cerebellum, cerebellar peduncles; stalks of axonal fibers which communicate between cerebellum and cortical/sc regions
- provides control over certain visceral functions (respiratory rate, heart rate, blood pressure, gi functions) via cranial nerves
- provides control over cerebral arousal level (level of consciousness) via reticular formation

- contains various nuclei other than cranial nerves, among them:
--- vestibular nuclei: which feed info from vestibular system to vestibulospinal tract
--- red nucleus: which feeds info from cerebellum to rubrospinal tract
What are the three divisions of the brainstem (superior to inferior)? ***
- midbrain
- pons
- medulla oblongata
All divisions of the brainstem contain: ***
- ascending/descending tracts
- different cranial nerve nuclei
- cerebellar peduncles
- portions of reticular formation
Describe the medulla oblongata. ***
- most inferior aspect of brainstem
- direct communication to SC

- contains decussation of pyramids, decussation of dorsal column tracts
- cardiovascular and respiratory reflex centers
Cranial nerve locations ***
(see picture)
Describe the pons. ***
- superior to medulla
- contains vestibular nuclei (vestibulospinal tracts)
Describe the midbrain. ***
- extends from pons region to thalamus, smallest region of brainstem

- contains red nucleus cell bodies feeding rubrospinal tract

- periaqueductal gray (gray matter containing endorphin producing cells which suppress pain)
Describe the cranial nerves. ***
- 12 pairs, exit/enter in or near brainstem level

- 9 emerge solely from brainstem;
---- CN I and II are not true nerves but fiber tracts from the brain,
---- CN XI is derived in part from upper cervical spinal nerves

- some cranial nerves purely sensory, some are purely motor, some are both
- some innervate visceral components, some somatic
Clinical signs with involvement of CN nuclei (ipsilateral): ***

absence of pupil constriction
Clinical signs with involvement of CN nuclei (ipsilateral): ***

- strabismus
- diplopia
- ptosis
Clinical signs with involvement of CN nuclei (ipsilateral): ***

- facial anesthesia/pain
- mouth/gums (pain?)
- difficulty chewing

- Tic Doloureaux - excruciating pain in CN V distribution
Clinical signs with involvement of CN nuclei (ipsilateral): ***

- dry eye
- dry mouth
- paralysis of facial muscles of expression
- inability to close eyelid

- Bell's Palsy - facial paralysis
Clinical signs with involvement of CN nuclei (ipsilateral): ***

cochlear nucleus
- tinnitus
- deafness

vestibular nucleus
- vertigo
- vomiting
- nystagmus
Clinical signs with involvement of CN nuclei (ipsilateral): ***

CN IX and X
- difficulty swallowing
- dysphonia
- hoarseness
Clinical signs with involvement of CN nuclei (ipsilateral): ***

- weakened shoulder shrug and head turning
Clinical signs with involvement of CN nuclei (ipsilateral): ***

- paralysis of side of tongue with deviation of protruded tongue to that side
Clinical signs with impairment of ascending/descending tracts (contralateral.) ***
- primarily impairment of corticobulbar/spinal tract
- contralateral hemiplegia/sensory loss

- "Locked-in syndrome": occlusion of vascular supply to pyramidal tract, results in loss of motor/speech; reticular formation intact; alert and aware but only possible movement is slight eye movement
(Diving Bell and the Butterfly)
Describe the reticular formation. ***
- reticular nuclei and tracts
- dotted lines indicate the extent of the reticular formation

- reticular nuclei include the ventral tegmental area, pedunculopontine nucleus, locus ceruleus, and raphe nuclei
- two of the upper motor neuron tracts that arise in the reticular formation, the reticulospinal tracts, are shown
- the ceruleospinal and raphespinal tracts also arise in the reticular formation (not illustrated).
Clinical signs with impairment of reticular formation. ***
- decreased level of consciousness
- coma
Describe the cerebellum. ***
- second largest part of brain
- consists of two lateral hemispheres which communicate with rest of CNS via cerebellar peduncles

- has cortex (gray matter), deep white matter, deep nuclei
- does not initiate motor activity but regulates/modifies motor activities
What are the cerebellar peduncles? ***
fibers connecting cerebellum to brainstem
Function of the cerebellum ***
- receives sensory input from many areas (primarily vestibular system, proprioceptors in muscles/spinocerebellar tract)
- not a part of conscious sensory awareness, deals with unconscious sensory

control center for:
- coordination of voluntary muscle activity
- equilibrium and balance
- muscle tone
- some evidence of involvement in memory

relays modification information to PNS indirectly through numerous circuits in brainstem/cerebrum, corticospinal tract

cerebellar input :
- proprioceptive info from muscles regarding speed and position and tone (muscle spindles, GTO)
- equilibrium info from vestibular system (elicits postural adjustments in response to head tilt)
- motor commands from cerebral cortex
Clinical signs of cerebellar lesions ***
- unilateral lesions lead to motor disabilities ipsilateral to the side of the lesion

- usually have bilateral cerebellar damage with bilateral involvement
- lesions do not cause paralysis but result in uncoordinated, poor quality movement and overall low tonus

- hypotonia
- ataxia
- nystagmus
- dysmetria
- intention tremor
- postural tremor
- rebound phenomenon
- dysdiadochokinesia
- dysarthria
- disorders of gait
What is hypotonia? ***
- sign of a cerebral lesion

-decreased muscle tone
- muscles feel soft and flabby
What is ataxia? ***
- sign of a cerebral lesion

- loss of coordinated muscular contractions required for production of smooth movements
- jerky, irregular movements instead of smooth continuous movements

- inconsistent speed of movement (affects posture, gait, limb movements)

- feedback loops not working properly
What is nystagmus? ***
- sign of a cerebral lesion

- rhythmic oscillation of eyeballs
What is dysmetria? ***
- sign of a cerebral lesion

- impaired ability to judge distance or range of movement (overshooting or undershooting a target, e.g, when trying to grab an object)
What is intention tremor? ***
- sign of a cerebral lesion

- tremors of extremity during movement that disappear at rest
What is dysdiadochokinesia? ***
- sign of a cerebral lesion

- impaired ability to perform rapidly alternating movements (e.g., walking)
What is rebound phenomenon? ***
- sign of a cerebral lesion

- loss of normal checks of agonist and antagonist muscles
What is postural tremor? ***
- sign of a cerebral lesion

- back and forth oscillatory movements of body in static posture
What is dysarthria? ***
- sign of a cerebral lesion

- slow, slurred speech
What disorders of gait are noted in conjunction with cerebellar lesions? ***
- broad base of support
- arms held out away from body to improve balance
- inconsistent speed of gait
- irregular gait pattern with deviation from forward line of progression (staggering)
What is the diencephalon? ***
- mass of gray matter (numerous large nuclei)
- superior to brainstem and deep in cerebrum
- contains 3rd ventricle which lies between the halves of the diencephalon
Name the divisions of the diencephalon. ***
- thalamus
- hypothalamus
- subthalamus
- epithalamus
Describe the structure and function of the thalamus. ***
- largest gray matter structure in diencephalon; contains clusters of nuclei
- involved with movement, sensation, emotion, and memory information

- major relay station for ascending pathways (mainly afferent)
- most sensory nerve tracts from spinal cord and brainstem synapse in thalamus

- thalamic neuron axons project to cerebral cortex (somatotopic representation) (large % to parietal lobe)
Most sensory nerve tracts from the spinal cord and brainstem synapse in the _______. ***
Which is the largest gray matter structure in the diencephalon? ***
With what functions is the thalamus involved? ***
- movement
- sensation
- emotion
- memory information
How is sensory information perceived in the thalamus? ***
- interprets sensory information, especially pain/noxious sensation
- sensation is perceived by brain at this region but location is not interpreted until it reaches cortex (you can feel but you cannot locate the area)

(of course it also depends on the wiring of the individual for the definition of “noxious”)

- also connects with basal ganglia (deep within the cerebral hemispheres), cerebellum, and limbic system)
Describe the structure and general function of the hypothalamus. ***
- group of nuclei inferior to thalamus

- responsible for important regulatory functions of body’ systems; maintenance of homeostasis
For what functions is the hypothalamus the control center? ***
- appetite
- autonomic function (activation of ANS/visceral functions)
- body temperature (activates responses resulting in loss, conservation, or production of body heat)

- circadian rhythm: (24 hr cycle of body functions: temperature, O2 consumption, corticosteroid levels cyclically influenced by light intensity)
- expression of emotions (rage, fear, aversion, sexual behavior, pleasure)

- growth, reproduction, sexual functions (via regulation of endocrine system)
- water balance (fluid retention/excretion)
Describe the structure and function of the subthalamus. ***
- nucleus located near the thalamus
- part of the basal ganglia system

- plays a part in modifying motor responses
Describe the structure and function of the epithalamus. ***
- uppermost portion of diencephalon

- consists of various structures including pineal gland (which influences body’s response to light)
List two effects of lesions to the diencephalon. ***
- thalamic pain syndrome
- hemiballismus
Describe thalamic pain syndrome. ***
- vascular damage to thalamus (certain CVAs) result in distortion of all sensory input from contralateral side of the body

- usually accompanied by contralateral paralysis/paresis due to CVA damage to cerebrospinal tract

- patient develops exaggerated responses of burning, agonizing pain in all affected body parts with any type of sensory stimulation to affected areas
Describe hemiballismus. ***
- lesion to subthalamic nucleus

- involuntary, sudden wild flailing motions of contralateral side of the body
Describe the structure of the basal ganglia. ***
- consists of several large nuclei located deep within cerebral hemispheres between thalamus and cerebral cortex of each hemisphere

- contains internal capsule: projection that allows fibers to communicate between basal ganglia and other motor areas in the brain

- misnomer: these masses are nuclei not “ganglia” and some are not basal
- part of “extrapyramidal system” (motor regions other than corticospinal tract which is referred to as “pyramidal system”)

- caudate nucleus
- putamen
- globus pallidus
- subthalamus
What are the functions of the basal ganglia? ***
collaborates with all motor areas of brain (cerebral cortex, cerebellum, brainstem, diencephalon) for:
- planning, programming, modification of motor commands (activities)
- subconscious control system for automatic motor activities such as coordinated movements and postural adjustments
What are some clinical signs of basal ganglionic lesions? ***
malfunction may result in movement disorders (dyskinesia – abnormal movement)
(either too much movement or too little movement, depending on area effected)

clinical signs of lesions:
- akinesia - inability to initiate movement
- rigidity – hypertonicity
- resting tremor – rhythmic oscillatory movements at rest

- chorea – involuntary rapid jerky movement
- tics – spasmodic jerking of muscles, usually facial/neck
- athetosis – involuntary writhing, twisting mvts.
- hemiballismus – involuntary sudden, wild flailing motions of one side of the body
Name two examples of basal ganglia disorders. ***
- Parkinson's Disease

- Tourette's Syndrome
Describe the general function of the cerebrum. ***
- largest, most prominent part of brain
- dominates all other aspects of nervous system

- interprets all sensory information
- initiates all volitional motor activities
- serves as the center of intellect, memory, language, behavior
Describe the landmarks of the cerebrum. ***
external landmarks of cerebrum:

- sulcus: depression or groove
--- central sulcus – located middle of hemisphere (medial to lateral/coronal) separates frontal from parietal lobe
- fissure: deep groove
--- lateral fissure – separates temporal lobe from parietal and frontal lobes

- gyrus: convolutions or folds of cerebrum; lie between two sulci
--- precentral gyrus – located anterior to central sulcus; frontal lobe
--- postcentral gyrus – located posterior to central sulcus; parietal lobe
What are the general functions of each hemisphere of the cerebrum? ***
- each controls the contralateral side of the body for the majority of sensory and motor functions
- each has four lobes: 1. frontal 2. parietal 3. temporal 4.occipital

--- frontal: primary motor cortex, premotor area, prefrontal area
--- parietal: primary somatosensory cortex (pinch is on the arm), sensory association area
--- temporal: primary auditory cortex, auditory association area
--- occipital: primary visual cortex, visual association area
Describe the structure of the hemispheres of the cerebrum. ***
- each has an outer layer of gray matter; cerebral cortex (composed of motor—mostly frontal and sensory cell bodies—mostly parietal/interneuronal cell bodies)

- each contains neuronal fibers deep to cortex (subcortical white matter), necessary for processing/integrating sensorimotor information and higher level mental/motor function

- each hemisphere contains deeper gray matter (nuclei) structures:
(e.g., basal ganglia, thalamus, hypothalamus, epithalamus, subthalamus)

- each hemisphere contains a lateral ventricle
Name and describe the fibers associated with the cerebrum. ***
- association fibers (axons): interconnect neurons within the lobes (long and short)

- commissure fibers: interconnect neurons between the two hemispheres, largest is the corpus collosum which represents the main communication link between right and left hemispheres, most information is transferred between hemispheres at this site

- projection fibers: ascending/descending neuronal fibers within brain and spinal cord

- cingulum
Name the largest structure of commissure fibers within the cerebrum. ***
corpus collosum
Describe the function of the frontal lobe. ***
primary motor cortex
- motor control
- beginning of final common pathway for voluntary motor function
- somatotopic (body map) representation of body regions (homunculus)
--- allocates 2/3 cortex for fine motor functions (hands, face, tongue)
--- allocates 1/3 for gross motor functions (trunk, UE, LE, feet)
Describe the structure and function of the premotor area of the frontal lobe. ***
- complex motor function

- connected neuronally to primary motor cortex via association fibers, work together to perform coordinated/simultaneous/complex movements
(e.g., throwing ball, driving car while changing radio station, or talking while cooking)

- contains Broca’s area (motor for lips and tongue, important for speech)
Describe the structure and function of the prefrontal area of the frontal lobe. ***
- connects with all other lobes of hemispheres

- abstract thinking, planning, judgment, personality, intellect

- forms part of limbic system (self-control, emotion, social behavior) – affected by all other systems
Describe the function of the parietal lobe. ***
- primary somatosensory cortex (postcentral gyrus)

- terminal point for somatosensory input relayed from thalamus
- receives, interprets, processes sensory input from body

- sensory modalities include pain, temperature, touch, vibration, pressure, position/movement sense (no vision, smell, auditory as those are via cranial nerves)

- localizes the sensation
- representation of body regions (homunculus) allocates 2/3 to face, mouth, hand, and foot
What is the sensory association area? ***
an area posterior to postcentral gyrus that:
- integrates all sensory information from primary somatosensory cortex
- responsible for higher order of sensory discrimination (stereognosis—know by feel, two point discrimination, graphesthesia—recognize writing on skin)
- also receives and integrates sensory information from other lobes (visual, taste, and language, both spoken and written)
What functions are performed in the temporal lobe? ***
primary auditory cortex
- inside lateral fissure
- receives neuronal input from both inner ears
- sound is “realized” here but not comprehended

auditory association area (surrounds primary auditory cortex)
- interprets and integrates auditory information with all other incoming sensory information for appropriate response
- contains Wernicke’s area (interprets sounds as words)

- long-term memory storage

- forms part of limbic system (involved with emotion, behavior)
What functions are performed in the occipital lobe? ***
primary visual cortex (medial surface of occipital lobe)
- receives visual information via optic nerve

visual association area
- interprets and integrates visual information with all other incoming sensory information (where object is and what object is) for appropriate response
What is the sensory homunculus? Where is it represented? ***
cortical homunculus is a somatotopic representation of the body parts on the pre/post-central gyri

sensory homunculus
- area on postcentral gyrus (primary somatosensory cortex) which localizes sensory input from a specific area from contralateral body
- each point on the skin/body projects sensory information via a single axonal path to a single point on primary somatosensory cortex
- face, mouth, hand, foot occupy approximately 2/3 of sensory homunculus (lots of sensory input from this area) = SURVIVAL
What is the motor homunculus? Where is it represented? ***
cortical homunculus is a somatotopic representation of the body parts on the pre/post-central gyri

motor homunculus
- area on precentral gyrus (primary motor cortex) specific to each region of contralateral body commanding individual muscle actions via single axonal path
- motor commands originate in precentral gyrus, travel in cortico-bulbar/corticospinal tracts to motor nuclei in brainstem/spinal cord
- face, mouth, throat, head occupy approx 2/3 of motor homunculus (lots of motor fibers to areas requiring complex, skilled movement)
How does handedness/hand dominance affect cortical function? ***
- primary and association sensorimotor areas are present in both hemispheres/all lobes
- both hemispheres receive, process and integrate the same basic information

- evidence shows that functional asymmetries exist concerning left and right hemisphere methods of processing this information

- beginning early in life, one hemisphere of the brain develops more intensively than the other for language and speech function
- this is often referred to as the “dominant” hemisphere

- dominant hemisphere is concerned particularly with analytical functions; speech, language, literacy, “reading” music, analytical mathematics
- “non-dominant” hemisphere plays a greater role with interpretation of 3-dimensional images and spatial relationships; design, drawing, music appreciation, dance, person space/body awareness, theoretical mathematics
With which cortical functions is the dominant hemisphere concerned? ***
- dominant hemisphere is concerned particularly with analytical functions; speech, language, literacy, “reading” music, analytical mathematics
With which cortical functions is the non-dominant hemisphere concerned? ***
- “non-dominant” hemisphere plays a greater role with interpretation of 3-dimensiaonal images and spatial relationships; design, drawing, music appreciation, dance, person space/body awareness, theoretical mathematics
Which hemisphere is dominant in the majority of the population? ***
in the majority of population (90-95%), the
- left hemisphere is the dominant hemisphere (language, analytical tasks) and the
- right hemisphere is the non-dominant, hemisphere (spatial appreciation)
What types of lesions can affect the primary motor cortex and somatosensory cortex and their associated structures? ***
- edema
- infection/disease
- congenital defects
- vascular damage secondary to trauma
- strokes
- vessel malformations
How do lesions of the primary motor cortex affect function? ***
contralaterally: the area affected depends on somatotopic location
- muscle paresis (weakness) or paralysis (absence)
- spasticity (usually, but may be flaccid)
- hyperreflexia
How do lesions of the primary somatosensory cortex affect function? ***
contralaterally: the area affected depends on somatotopic location
- paresthesias (numbness, tingling, electric shock)
- impaired ability to distinguish or localize stimuli
- impaired ability to measure intensity of stimulus
How do lesions in the motor/sensory association areas affect function? ***
- motor association areas: movement will occur but will be uncoordinated, disorganized

- sensory association areas: sensations will be realized but will not be correctly interpreted/processed
How do lesions in the prefrontal lobe affect function? ***
prefrontal lobe: behavioral impairments, personality changes, impaired judgment, social disinhibitions, poorly controlled behavior
Describe the structure and function of the meninges. ***
- meninges cover the brain and are continuous with the spinal cord

- support brain within the skull
- protect the brain
- helps maintain a constant environment in and around brain
Name the three meningeal layers. ***
- dura mater
- arachnoid mater
- pia mater
Describe the dura mater. ***
- tough, fibrous outermost membrane

- consists of two layers
--- outer layer firmly attached to cranial bone
--- inner layer continuous with spinal dura

- layers generally fused except in areas where it separates to form venous sinuses (small cavities which collect venous drainage)

- form septa (divisions) separating and containing brain portions
--- falx cerebri - separates 2 hemispheres
--- tentorium cerebelli - separates occipital lobes from cerebellum

- subdural space between dura mater/arachnoid (potential space, normally contains only a few drops of CSF; bleeding into area with vascular trauma = subdural hematoma)
Name the septa of the dura mater. ***
- septa (divisions) separating and containing brain portions
--- falx cerebri - separates 2 hemispheres
--- tentorium cerebelli - separates occipital lobes from cerebellum
Describe the arachnoid mater. ***
- middle layer; delicate
- avascular
- weblike

- subarachnoid space between arachnoid mater/pia mater contains CSF and arteries
Describe the pia mater. ***
- innermost layer
- very thin
- completely invests brain

- combines with other tissue/vascular structures in the ventricle regions to form the choroid plexus (layer that produces CSF)
What does the choroid plexus do? ***
produces CSF
What effects can meningeal lesions have? ***
- brain herniations: separation of a septa can result in movement of brain tissue into another area

- herniated tissue can put pressure on other areas of brain
--- can be life threatening if brainstem is compressed (regulatory centers for respiration, consciousness, blood pressure, heart rate)
Describe the structure of the ventricular system. ***
- communicating system of 5 cavities deep within the brain

four ventricles:
--- 2 lateral ventricles; largest (one deep inside each cerebral hemisphere)
--- third ventricle (separates diencephalon)
--- fourth ventricle (within brainstem)

- interventricular foramen connects lateral/third ventricles
- cerebral aqueduct connects third and fourth ventricles
What is CSF? ***
cerebrospinal fluid

- clear, colorless, odorless fluid containing nutrients (glucose, proteins)
- produced by the choroid plexus (vascular process of the pia mater)

- choroid plexus components present in all ventricles except cerebral aqueduct (similar to an epithelial layer, but not epithelial)

- CSF is found in ventricular system and subarachnoid space surrounding BS and SC
What is the purpose of CSF? ***
- provides cushioning support of brain and spinal cord (CNS “floats” in CSF)
- delivers nutrients; transports wastes

- controls CNS excitability by regulating ionic composition
- provides some protection from pressure changes (venous volume vs. CSF volume)
Describe the route of CSF circulation? ***
- most is formed in lateral ventricles (choroid plexus);
- passes into third ventricle
- then through cerebral aqueduct into fourth ventricle

- through three small foramina into subarachnoid space; and
- circulates around entire surface areas of brain/spinal cord in subarachnoid space

- there is continuous circulation of CSF in and around brain and spinal cord

- CSF is reabsorbed by superior sagittal sinus (venous blood flow in superior aspect of brain) and returned to bloodstream
What is hydrocephalus? ***
- dilation of ventricles secondary to an abnormal accumulation of CSF

caused by:

- blockage of CSF flow (obstruction, malformation); referred to as non-communicating/obstructive hydrocephalus

- overproduction of CSF and/or inadequate reabsorption of CSF (obstruction of resorption sites); referred to as communicating hydrocephalus (more CSF is being produced than is reabsorbed)
What is the difference between non-communicating/obstructive hydrocephalus and communicating hydrocephalus? ***
- non-communicating/obstructive hydrocephalus is due to a blockage

- communicating hydrocephalus is due to overproduction of fluid
What are the sequelae from and treatment for hydrocephalus? ***
- results in increased intracranial pressure (ICP)
- if untreated
--- brain damage resulting in mental retardation
--- neurological deficits
--- cranial deformity (if under 2 years of age)
--- possible death

- shunt: Rx for hydrocephalus
- surgical implantation of catheter in ventricles with drain line which passes from ventricle to either right atria (ventriculoatrial shunt) or to right peritoneal cavity (ventriculoperitoneal shunt)

- control valve on catheter (in ventricle) regulates flow rate
- excess CSF is shunted to other body cavity
How is hydrocephalus diagnosed? ***
lumbar puncture (spinal tap)
- insertion of special spinal needle into subarachnoid space below the spinal cord level (L3, 4, 5 vertebral level)
What are some indications that may be diagnosed via spinal tap? Other uses for spinal taps? ***
- measure CSF pressure--increased pressure may be due to:
--- increased CNS volume = tumor
--- increased blood volume = hemorrhage
--- icreased CSF volume = hydrocephalus

- examine CSF for infections
- administer anesthesia
CNS cells and tissue require a continuous supply of ______ and _____ for normal functioning. ***
- glucose

- oxygen
Although the brain is only 2% of the total body weight, it uses _____ of cardiac output and ____ of oxygen absorbed by lungs. ***
- 18-20%

- 20%
If blood supply to CNS is restricted, how quickly can damage occur? ***
- loss of consciousness within 1 minute

- irreversible cell damage within 5 minutes (because once a CNS neuron is dead, it's dead--no regeneration)
Describe the distribution patterns of the large cerebral arteries. ***
- green area: anterior cerebral artery
- pink area: middle cerebral artery
- yellow area: posterior cerebral artery
How does blood flow from the heart to the brain? ***
- all arteries to brain arise from aortic arch

common carotids supply bulk of circulation to cerebrum
- bifurcate posterior angle of the jaw to internal and external carotids
--- external supplies face
--- internal supplies cranium and cerebral hemispheres, optic nerves, and retina
----- internal bifurcates into R and L anterior and middle cerebral arteries (together form anterior circulation to brain)
Which cerebral artery is the largest and most often occluded? ***
middle cerebral artery

(common carotid artery bifurcates at posterior angle of jaw into external and internal carotids;
internal bifucates into R and L anterior and middle cerebral arteries)
Describe the blood supply to brain stem and cerebellum. ***
- two vertebral arteries are branches of the subclavian arteries
- supply blood to brain stem and cerebellum

- enter skull through foramen magnum
- unite to form basilar (base--) artery

- anterior and posterior communicating arteries are interconnected at base of brain and form Circle of Willis (redundant blood supply)
What is the structure and function of the Circle of Willis? ***
- provides protection to structures of the brain

- failure or occlusion of one cerebral artery does not critically decrease blood flow to that region

- occlusion can be circumvented or bypassed to meet needs of cerebral tissue

from anterior to posterior, the arteries that form the circle of Willis are:
- anterior communicating
- two anterior cerebral
- two internal carotid
- two posterior communicating, and
- two posterior cerebral arteries.
Describe the venous drainange of the brain. ***
- cerebral veins differ from systemic veins
--- no valves
--- seldom accompany arteries

- smaller veins located deep in the brain travel to superficial surface of brain
- join larger veins which drain into venous sinuses located in dura mater

(pictured above are the sagittal sinus and transverse sinus)
Name the venous sinuses. ***
- superior sagittal
- inferior sagittal

- straight
- transverse
How do the sinuses route venous return to the superior vena cava? ***
sinuses converge at different areas and drain into internal jugular veins which drain into superior vena cava
What is the blood-brain barrier? ***
- certain structures in close contact with CNS (astrocytes, arterial vessels, arachnoid layer) are specially designed to serve as a protective barrier for the CNS

- these structures are designed with:
--- very tight intercellular junctions and/or
--- selective membrane permeability
How does the blood-brain barrier work? ***
design allows:
- selective passage of some substances into/out of the CNS but not others (promotes the exchange of O2, CO2, amino acids, sugars but not other substances such as large proteins

- protection for CNS from foreign substances (toxins) can be a problem when certain medicines are unable to cross

- stable metabolic environment for the CNS
Name some types of cerebrovascular disorders. ***
- CVA/stroke
- hemorrhage
What is a CVA? ***
- cerebrovascular accident (a.k.a. stroke)

- caused by thrombosis (due to atherosclerosis, arteriosclerosis) or embolism (thrombus, fat globule, air bubble, clump of bacteria)

- occlusion of artery results in ischemia to area of brain supplied and result is infarction
What is a TIA? ***
- transient ischemic attack
- often called a "mini stroke"

- caused by temporary occlusion of a narrowed vessel (vasospasm, traveling embolis, thrombosis)

- results in reversible neurologic deficits (dizziness, LOC, weakness, difficulty speaking); considered warning signs for impending CVA
What are some types of cranial hemorrhage? ***
- bleeding secondary to ruptured vessel, also a type of CVA

caused by:
- aneurysms resulting from chronic hypertension, vascular malformations, atherosclerosis, infection
--- named according to location: intracerebral hemorrhage, subarachnoid hemorrhage, or subdural hemorrhage

- tearing of vessels due to trauma
--- named according to location: subdural hematoma (venous) or epidural hemorrhage (arterial)
What constitutes the peripheral nervous system (PNS)? ***
- consists of all nervous tissue outside the vertebral canal

- formed by nerves leading to and from CNS

- nerves contain axonal fibers which conduct afferent/efferent information
--- cranial nerves 12 (pairs)
--- spinal nerves 31 (pairs) (mixed)
Describe the construct of a peripheral nerve from its origin in the spinal cord. ***
- spinal cord (in vertebral canal) gives rise to the ventral and dorsal roots at each segmental level
- ventral and dorsal roots are formed bilaterally from cord
--- ventral root consists of outgoing motor axon fibers
--- dorsal root consists of incoming sensory axon fibers

- roots join while in vertebral canal, form a single spinal nerve, pass out of vertebral canal via intervertebral foramen

- once outside of intervertebral canal, spinal nerve immediately splits into 2 branches (rami)
--- anterior (ventral) ramus – innervates autonomic nervous system, BUE/BLE and anterior/lateral aspects of trunk
--- posterior (dorsal ramus) innervates posterior trunk
Peripheral nerves contain nerve fibers which innervate both....
visceral organs and somatic structures (skeletal muscle, joints, bones, skin)
What tissues/structures comprise a peripheral nerve? ***
- made up of myelinated and/or unmyelinated axons which transmit either sensory or motor information

- mixed axons (myelinated/unmyelinated/sensory/motor) are each surrounded by a connective tissue sheath called endoneurium (inner) and then are grouped into bundles called fasiculi

- each fasciculus is surrounded by a connective tissue sheath called a perineurium (around)

- entire nerve is comprised of many fasiculi and is surrounded by tough connective tissue sheath called epineurium (over) (contains fat cells and small blood vessels)
What is the endoneurium? ***
surrounds the individual axon
What is the perineurium? ***
surrounds the fascicle
What is the epineurium? ***
surrounds an entire nerve
The PNS begins once the nervous tissue exits the _____ ______. ***
intervertebral foramen
Peripheral nerves are composed of _____ which may be either sensory or motor. ***
Many fasiculi surrounded and joined together by epineurium comprise a _____ _____. ***
peripheral nerve
What is a nerve plexus? ***
- a network of spinal nerves in one region

- anterior (ventral) rami of the spinal nerves join together, intermingle, split and regroup to form a network

- peripheral nerves are formed from each plexus

- occurs at every level except thoracic (direct innervation)
List the four major plexuses. ***
- cervical
- brachial
- lumbosacral
- coccygeal
Location and innervation:

cervical plexus ***
- C1-C4 spinal nerves

- innervates muscles of the neck and diaphragm
Location and innervation:

brachial plexus ***
- C5-T1 spinal nerves

- innervates muscles of the scapula and UE
Location and innervation:

lumbosacral plexus ***
- L1-S3 or T12-S3 spinal nerves

- innervates muscles of LE
--- lumbar division (L1-L4) or (T12-L4)
--- sacral division (L4-S3)
Location and innervation:

coccygeal plexus ***
- S3 – coccyx spinal nerves

- innervates muscles of the genitalia and perineum
What major nerves are part of the brachial plexus? ***
- C5-T1

- axillary nerve: deltoid, teres minor (C5-6)
- all scapular nerves: scapular muscles (C5-6)

- thoracodorsal nerve: lattisimus dorsi (C6-8)
- pectoral nerve: pectoralis major (C5-T1)

- musculocutaneous nerve: biceps, brachialis, coracobrachialis (C5-C7)

- radial nerve: triceps, wrist/finger extensors, supinator, brachioradialis (C5-C8)
- median nerve: pronators, FCR, FDS, FDP (radial side), thumb opposition, flexion, abduction, lumbricales 1,2 (C6-T1)
- ulnar nerve: FCU, FDP (ulnar side), interossei, lumbricales 4, 5 (C8 – T1)
What major nerves are part of the cervical plexus?
- vagus nerve (CN X)

- phrenic nerve (to diaphragm)
What major nerves are part of the lumbar division of the lumbosacral plexus? ***
lumbar division (L1-S3)
- obturator nerve: hip adductors (adductor magnus/longus/brevis)
- femoral nerve: hip flexors, quadriceps
What major nerves are part of the sacral division of the lumbosacral plexus? ***
sacral division (L4-S3)
- inferior gluteal nerve: gluteus maximus
- superior gluteal nerve: gluteus medius/minimus
- sciatic nerve: hamstrings (tibial branch - all, peroneal branch - biceps femoris short head)
--- tibial nerve: plantar flexors (gastroc, soleus), posterior tibialis
--- common peroneal nerve: no muscles directly
----- superficial peroneal nerve: peroneus longus, peroneus brevis
----- deep peroneal nerve: tibialis anterior, extensor hallucis longus
Besides innervating specific muscles, peripheral nerves also...
- innervate specific cutaneous areas (which differ from dermatomal areas)

- cutaneous areas (nerve fields) are sensory areas innervated by peripheral nerves

for example:
- axillary nerve innervates lateral arm over lower 2/3 of deltoid
- musculocutaneous nerve innervates lateral surface of forearm
- radial nerve innervates dorsal aspect of lateral half of hand (except dorsum of fingertips 2,3), lateral thumb
- median nerve innervates lateral half of palm and palmar aspect of thumb, digits 2,3,4 (radial side) and dorsum of finger tips 2,3
- ulnar nerve indicates medial half of hand, thumb, digits 2,3,4 (radial side)
- lateral femoral cutaneous nerve innervates anteriolateral aspect of thigh
- anterior femoral cutaneous nerve innervates anterior thigh to just below knee
- obturator nerve innervates middle of medial thigh, medioposterior aspect of thigh and knee
- common peroneal nerve innervates lateral aspect of lower leg just below knee level
- saphenous nerve innervates medial aspect of calf and heel
- superficial peroneal nerve innervates anteriolateral lower leg, dorsum of ankle and foot
- sural nerve innervates posterior calf and lateral half of foot
- deep peroneal nerve innervates triangle over dorsum of distal metatarsal 1 and 2

- tibial nerve (medial/lateral plantar nerve) innervates posteriolateral aspect of lower leg and sole of foot
What are some clinical signs and symptoms that indicate injury to a peripheral nerve? ***
- PNI results in both sensory and motor impairments

sensory impairment:
- if the area of sensory impairment follows a dermatomal pattern, then lesion is proximal (spinal nerve/nerve root injury); e.g., HNP with spinal nerve root impingement
- if area of sensory impairment follows cutaneous pattern (nerve field) then lesion is distal and is PNI. (e.g., entrapment, trauma, compression)

- loss of sensation (does not necessarily mean absence of sensation)
- paresthesias
- pain
- muscle weakness
- muscle paralysis
List some types of PNI. ***
- stretch (neurapraxia): shocks nerve, but does not tear; usually heals within 3 months

- neuroma: scar that develops due to injury

- rupture: complete disruption of nerve (requires surgical intervention; graft)

- avulsion: nerve torn from spinal cord

- compression: pressure causes myelin break down (we have to watch out for this/be sure that we are not causing this in many of our treatments)
What are some clinical signs and symptoms that indicate injury to a peripheral nerve? ***
- PNI results in both sensory and motor impairments

sensory impairment:
- if the area of sensory impairment follows a dermatomal pattern, then lesion is proximal (spinal nerve/nerve root injury); e.g., HNP with spinal nerve root impingement
- if area of sensory impairment follows cutaneous pattern (nerve field) then lesion is distal and is PNI. (e.g., entrapment, trauma, compression)

- loss of sensation (does not necessarily mean absence of sensation)
- paresthesias
- pain
- muscle weakness
- muscle paralysis
List some causes of PNI. ***
Nerve entrapment/compression due to:
- inflammation/edema of surrounding soft tissue
- bony impingement
- tight cast
- poor positioning
- trauma: lacerations, stretching, fractures
- disease process: viral infection, arthritis, vascular insufficiency
List some types of PNI. ***
- stretch (neurapraxia): shocks nerve, but does not tear; usually heals within 3 months

- neuroma: scar that develops due to injury

- rupture: complete disruption of nerve (requires surgical intervention; graft)

- avulsion: nerve torn from spinal cord

- compression: pressure causes myelin break down (we have to watch out for this/be sure that we are not causing this in many of our treatments)
What are some clinical signs of injury to the axillary nerve? ***
impairment in shoulder
- flexion
- extension
- abduction
List some causes of PNI. ***
Nerve entrapment/compression due to:
- inflammation/edema of surrounding soft tissue
- bony impingement
- tight cast
- poor positioning
- trauma: lacerations, stretching, fractures
- disease process: viral infection, arthritis, vascular insufficiency
What are some clinical signs of injury to the musculocutaneous nerve? ***
impairment in elbow
- flexion
- supination
What are some clinical signs of injury to the axillary nerve? ***
impairment in shoulder
- flexion
- extension
- abduction
What are some clinical signs of injury to the musculocutaneous nerve? ***
impairment in elbow
- flexion
- supination
What are some clinical signs of injury to the median nerve? ***
impairment in:
- pronation

- opposion
- flexion
- abduction
What are some clinical signs of injury to the radial nerve? ***
impairment in:
- elbow extension
- wrist extension
- finger extension
- thumb extension
What are some clinical signs of injury to the ulnar nerve? ***
impairment in:
- wrist flexion
- finger flexion
- intrinsics
What are some clinical signs of injury to the femoral nerve? ***
impairment in:
- hip flexion
- knee extension
What are some clinical signs of injury to the obturator nerve? ***
impairment in:
- hip adduction
What are some clinical signs of injury to the sciatic nerve? ***
impairment in:
- hip extension
- knee flexion
- actions below (tibial/peroneal)
What are some clinical signs of injury to the tibial nerve? ***
impairment in:
- plantar flexion
- inversion
- toe flexion
What are some clinical signs of injury to the common peroneal nerve? ***
impairment in:
- dorsiflexion
- eversion
- toe extension
What occurs with compression of the long thoracic nerve? ***
- winging of the scapula

(serratus anterior: stabilizes scapula against chest wall)
What occurs with entrapment or direct trauma to the radial nerve? ***
- drop wrist (usually distal to triceps)

(triceps, wrist and finger extensors affected)
What occurs with entrapment/compression of ulnar and median nerves? ***
Wrist/finger flexors, intrinsics are affected:
- wrist/finger flexion, abduction/adduction, and flexion of MCP/extension of IPs

- if ulnar nerve only: cubital tunnel = ulnar wrist and hand (claw hand)

- if median nerve only: CTS
What two hand deformities can be caused by entrapment/compression of the medial nerve? ***
- atrophy of thenar eminence (CTS)

- "benediction hand"
What occurs with entrapment of sciatic nerve? ***
- piriformis syndrome

- hamstrings
- plantar flexors
- dorsiflexors
- toe flexors and extensors

- deficit: weakness in hip extension, knee flexion, PF, toe flexion
What occurs with compression of tibial nerve? ***
- popliteal fossa, baker’s cyst

- triceps surae: tibialis posterior, toe flexors, PF, invertors
- deficits: absence of above actions, no push off with gait
What occurs with compression of common peroneal nerve? ***
- peroneals
- anterior tibialis
- toe extensors
- everters
- dorsiflexors

- inability to DF foot during gait,
- drop foot,
- steppage gait
What occurs with Morton's neuroma? ***
enlargement of conjoined lateral and medial plantar nerve may be caused by high heels or pes planus
What occurs with diabetic neuropathy? ***
- damage to nerves due to elevated blood glucose

- decreased sensation (stocking glove)

- deficits after chemo too.
What is the ANS? ***
- division of the peripheral nervous system

- consists of efferent and afferent fibers which innervate viscera

- controlled by various areas of the CNS (SC, BS, hypothalamus)

- hypothalamus primary coordinator of ANS functions
Which structure is the primary coordinator of ANS functions? ***
What is the hypothalamus' role in ANS function? ***
receives and integrates information regarding:
- oxygen levels
- blood pressure
- visual, auditory, olfactory
- emotions

- discharges appropriate command to ANS
How does information in the ANS get from the spinal cord to the target organ, gland, or smooth/cardiac muscle? ***
- via a 2 neuron chain (from spinal cord or brainstem to target structure)

- primary neuron (preganglionic neuron) originates in lateral gray column
- fibers then travel away from spinal cord via ventral ramus and quickly exit.

- at some point fibers synapse with 2nd order neuron (postganglionic neuron) located in autonomic ganglia, at different areas in the PNS, then fibers travel on to target tissue
What are the functions of the ANS? ***
- innervate smooth muscle (organs, vessels), cardiac muscle, glands

- maintains homeostasis of the organism; keeps internal system in balance

- maintains proper visceral functioning during situations requiring extreme responses

- no volitional control
What are the divisions of the ANS? ***
- sympathetic

- parasympathetic
How are most organs controlled by the sympathetic and parasympathetic nervous systems? ***
- majority of visceral structures receive innervation from both

- divisions are antagonistic to one another; each system is constantly firing to visceral structures; with one or the other dominating as the situation requires

- directed by CNS through hypothalamus
How does information flow in the ANS? ***
- visceral and vascular receptors send information to
--- limbic system
--- hypothalamus
--- reticular formation
--- spinal cord

- which work together, and send information via the
--- sympathetic division,
--- parasympathetic division, or
--- hormonal (endocrine) system)
Describe the sympathetic division of the ANS. ***
- thoracolumbar (only)

- located at spinal cord levels between T1 and L3

- lateral horn of spinal cord to ventral root
- exits at communicating ramus (white)
- then to sympathetic trunk (paravertebral ganglia)
- either re-enters spinal nerve
- or travels on to target viscera (cranial or sacral levels, via collateral ganglia, or direct to the adrenal medulla)
What is the sympathetic route in path ***
- through the paravertebral ganglionic chain and direct to synapse within the adrenal medulla

- via the paravertebral ganglionic chain upward into the cranial region to synapse with the postganglionic neuron (could've gone sacral as well)--sympathetic nerve route

- through the paravertebral ganglionic chain to synapse in a collateral (prevertebral) ganglia (in this case, the celiac) before traveling on to the associated organs--splanchnic nerve route
What is the purpose of the sympathetic nervous system? ***
- prepares the body for "fight or flight"

- stimulates activity; dominates in stressful situations

- neurotransmitters released at post-ganglionic endings:
--- epinephrine,
--- norepinephrine
--- adrenalin (adrenaline/noradrenaline are the same thing as epinephrine/norepinephrine)
(all secreted by adrenal medulla)

- not mentioned on our slides, but the postganglionic neurons also release acetylcholine (only with sweat glands and some smooth muscle)
Describe the parasympathetic nervous system. ***
- craniosacral
- located "around" the sympathetic nervous system (cranially and caudally)

- cranial - exits with CN III, CN VII, CN IX, CN X
- sacral - exits spinal cord with sacral nerves to ventral root

- either travels with spinal nerve or to outlying ganglia, or exits at communicating ramus, then travels on to target viscera
What is the purpose of the parasympathetic nervous system? ***
- basically opposes the sympathetic nervous system
- sets body up to "rest and digest" -- vegetative functions such as feeding and emptying

- conserves and restores energy; dominates in relaxing, restful activity

- neurotransmitters released
--- acetylcholine at both pre and postganglionic synapses
How do the sympathetic and parasympathetic nervous systems affect the eye? ***

(She said memorize these!!)
S - dilates pupil

P - constricts pupil
How do the sympathetic and parasympathetic nervous systems affect the salivary glands? ***

(She said memorize these!!)
S - stimulates thick, viscous mucus

P - stimulates watery secretions
How do the sympathetic and parasympathetic nervous systems affect the lungs? ***

(She said memorize these!!)
S - dilates bronchi and increases respiratory rate

P - constricts bronchi
How do the sympathetic and parasympathetic nervous systems affect the heart? ***

(She said memorize these!!)
S - increases heart rate and blood pressure

P - decreases HR and BP
How do the sympathetic and parasympathetic nervous systems affect the vessels? ***

(She said memorize these!!)
S - vasoconstriction

P - dilation (or no effect)
How do the sympathetic and parasympathetic nervous systems affect the stomach/intestines? ***

(She said memorize these!!)
S - decreases motility

P - increases motility
How do the sympathetic and parasympathetic nervous systems affect the liver? ***

(She said memorize these!!)
S - stimulates glycogen breakdown

P - no effect
How do the sympathetic and parasympathetic nervous systems affect the adrenal glands? ***

(She said memorize these!!)
S - stimulates release of epinephrine

P - no effect
How do the sympathetic and parasympathetic nervous systems affect the pancreas? ***

(She said memorize these!!)
S - no effect

P - increases secretion
How do the sympathetic and parasympathetic nervous systems affect the bowel and bladder? ***

(She said memorize these!!)
S - contracts sphincters

P - inhibits sphincters
Describe the actions that would be taken by the ANS in the case of an appendicitis attack. ***
- autonomic fibers carry info to BS, hypothalamus, limbic system (divergence of neuron carrying incoming pain signal)

- pain referred to umbilical region (looks like by a long reflex arc?)
- sympathetic efferents inhibit peristalsis (again, long reflex arc?)

- somatic efferents cause abdominal muscle contraction
(because of close proximity of neurons)
List some special feedback systems. ***
- visual system
- auditory system
- vestibular system
- reticular formation
- limbic system
What components comprise the visual system? ***
consists of:
- muscles controlling eye movement
- optical components (eyeball, cornea, iris, lens, and retina)
- optic nerve
- optic chiasm (where optic nerves cross)
- optic tract
- visual cortex/association areas (occipital lobe)
What are the functions of the visual system? ***
- detects light and differences in light patterns (shapes, color, movement)

- transforms information into electrical impulses which travel to the visual cortex where the signals are decoded and we “see” and recognize objects

- light passes through optical components of the eyeball
--- special sensory receptors (rods and cones/approximately 126 million receptors)
transform light rays and color spectrum into electrical signals
--- transmitted along the optic nerve from each eye, decussate and form the R and L optic tract

- each optic tract carries fibers from half of each retina
- tracts travel to brainstem
- from brainstem to cortex/visual association areas (occipital lobes)
How do the visual pathways function? ***
- visual information from the right visual field activates neurons in the left half of the retina of both eyes

- axons from the temporal half of the retina project ipsilaterally, while axons from the nasal half of the retina cross the midline in the optic chiasm to project to the contralateral side
What is the visual field and how is it created? ***
- amount of the world you see at anyone time, without eye or head movements

- lateral (temporal) and medial (nasal) halves in each eye work together to produce a R and L visual field
For what kinds of behaviors are visual and vestibular information important? ***
- generating eye movements which allow observation of a moving or stationary object

- maintaining an upright posture

- keeping track of your own position in space
List some disorders of the visual system. ***
- ptosis (droopy eyelid)
- strabismus (misalignment)
- diplopia (double vision)

- lesions to CN III, IV, or VI affect movement of eyes and eyelids
- cataracts (clouded lens)

- visual field deficits (binasal hemianopia, bitemporal hemianopia, homonymous hemianopia)
- cortical blindness (cannot interpret input)
What are cataracts? ***
- most common cause of blindness in U.S.
- lens becomes clouded due to aging, infection, trauma, or UV exposure)
- can be surgically corrected
What is binasal hemianopia? ***
medial half of visual field impaired, resulting in no central vision

(#2 is bitemporal hemianopia--the opposite/inverse would be binasal hemianopia)
What is bitemporal hemianopia? ***
lateral half of visual fields impaired resulting in tunnel vision; no peripheral vision

(# 2 is bitemporal hemianopia)
What is homonymous hemianopia? ***
defect in temporal half of one eye and nasal half of other eye resulting in loss of either the R visual field or the L visual field (occurs with some CVA patients)

(#3 is homonymous hemianopia)
Name the pictured visual field deficits. ***
- right optic nerve lesion
- bitemporal hemianopia (opposite would be binasal hemianopia)
- homonymous hemianopia
- left inferior homonymous quadrantanopia due
to right temporal lobe lesion
What is cortical blindness? ***
- appropriate electrical impulses are delivered to visual cortex (occipital lobe)

- information cannot be decoded; patient cannot interpret visual information
Which areas of the cortex direct eye movements? ***
(see picture)
What structures comprise the auditory system? ***
- external ear (pinna, external auditory meatus)
- middle ear (ear drum/tympanic membrane, ossicles)
- inner ear (cochlear duct/cochlea, organ of Corti)

- cochlear division of CN VIII

- ear is a transducer
How does the auditory system function? ***
- ear is a transducer
- transforms mechanical energy (vibrations) into electrical impulses which travel to the auditory cortex where the signals are decoded and we “hear” sounds

- sound waves converge through outer ear and strike tympanic membrane
--- vibrations of membrane transmitted by way of ossicles to cochlear duct
--- vibrations stimulate hair cells in organ of Corti by way of mechanical distortion
--- electrical signals travel along the cochlear nerve to brainstem

- from brainstem, signals transmitted to various regions of CNS
--- reflex nuclei in BS (response to strong, sudden sounds causing reflex turning of head toward sound)
--- cerebellum
--- reticular formation
--- thalamus
--- auditory cortex/association areas of temporal lobe
List some common disorders of the auditory system. ***
- tinnitus
- deafness
What is tinnitus? ***
ringing, buzzing, or roaring noises in the ear (can be early sign of cochlear disease) more of a symptom than a pathology
What is deafness? ***
- conduction deafness (external/middle ear damage)
- nerve deafness (inner/cochlear nerve damage)
What structures comprise the vestibular system? ***
- vestibular labyrinth located in inner ear (3 semicircular canals containing endolymph fluid)

- special receptor organs covered with hair cells (located within the labyrinths)

- vestibular divisions of CN VIII
What are the functions of the vestibular system? ***
- proprioceptive system of the head
- detects head position/movement

- stimulation of receptor organs occurs with head position/movement and
- electrical signals are transmitted along the vestibular nerve to brainstem
- from brainstem signals are transmitted to various regions of CNS

- information received used for:
--- posture
--- eye movements
--- control of equilibrium
--- spatial orientation
From the brainstem, vestibular system information is transmitted to where? ***
- vestibulospinal tract (reflex responses with result in extension patterns in trunk/extremities with rapid change in head position)

- cerebellum
- CN III, IV, VI for eye movements (keeps eyes constant in relation to environment during movement of head)

- reticular formation
- thalamus
- postcentral gyrus and sensory association areas (parietal lobe)
To which other systems is the vestibular system closely related? ***
- auditory system (physical location)

- visual system (function)
List some common disorders of the vestibular system. ***
- nystagmus (involuntary oscillation of eyeballs)

- vertigo (illusionary sensation of moving about in space or of objects moving about; disorientation in space)
Describe the vestibular apparatus. ***
- consists of the utricle, saccule, and semicircular canals
- three semicircular canals are at right angles to each othe
- each semicircular canal has a swelling, the ampulla, which contains a receptor mechanism, the crista

- bending of the hair cells changes pattern of firing in the vestibular neurons
- inside the utricle and saccule is a receptor called the macula
- in the macula, hairs projecting from hair cells are embedded in a gelatinous material

- atop the gelatinous material are otoconia: small, heavy, sandlike crystals
- when the macula is moved into different positions, weight of the otoconia bends the hairs, stimulating the hair cells and changing the pattern of vestibular neuron firing.
What is the reticular formation? ***
- vast complex of intermingled gray and white matter extending through entire brainstem, hypothalamus, thalamus and projection fibers to cortex (varying spots, not an actual “formation”)

- multiple interconnections with various aspects of the nervous system

- projects fibers to spinal cord via reticulospinal tract
What are the functions of the reticular formation? ***
- regulation of arousal, level of consciousness, and sleep (multiple interconnections with various sensory pathways; auditory, visual, visceral, and somatosensory)

- contributes to input for postural control and reflexes via communication with cerebellum, vestibular system, and reticulospinal tract
- contributes to some autonomic functions via respiratory and BP reflex centers in brainstem

- performance of motor tasks is influenced by level of alertness (related—increase your alertness, enhance performance/ability to respond)
- reticular system affects movement:
--- interconnections with cortex and reticulospinal tract
- high arousal state = alert, quick to respond with or to movements
- low arousal state = slowed responses, movements tend to be sloppy (groggy, sleepy)
List some disorders of the reticular system. ***
- infections
- tumors
- profound loss of consciousness: coma

(coma may also occur with extensive damage to cortex and extracranial injuries)
What structures comprise the limbic system? ***
- limbic cortex deep in cerebral cortex; includes portions of temporal and frontal lobes
- contains some of the most primitive/ancient portions of cerebrum

- linked up with prefrontal cortex, temporal lobe, hypothalamus/autonomic nervous system, basal ganglia, and reticular formation
- olfactory system closely linked to many limbic structures
What are some functions of the limbic system? ***
- contribute to species survival

- olfactory system closely associated:
--- feeding behavior
--- sexual behavior
--- aggression
--- expression of emotion
--- conversion of memory (short-term to long-term memory)
How does the limbic system affect movement? ***
- interconnects with hypothalamus which links with ANS to deal with stresses; keeps body “revved up”

- interconnects with basal ganglia to integrate long-term memory of movement

- interconnects with reticular formation to link effects of moods and emotions on movement (happy moods increase level of arousal; depressed moods decrease arousal level)
What are some signs and symptoms of limbic system lesions? ***
- mood personality disorders believed to originate in the limbic system (schizophrenia, depression, anxiety, phobias, and hypersexuality)

- long-term memory deficits (amnesia)

- eating disorders
- olfactory disorders (loss of smell, perverted smell and smell hallucinations)
- temporal lobe epilepsy
Pyramidal system ***
motor cortex and corticospinal tract
Extrapyramidal system ***
basal ganglia and other subcortical structures/tracts influencing motor commands:
- rubrospinal,
- reticulospinal and
- vestibulospinal tracts
Motor system ***
consists of
- cortical and subcortical gray matter,
- descending efferent tracts, and
If a person has a lesion in the given area, state the effect on discriminative touch and conscious proprioceptive information: ***
- cerebrum, midbrain, pons, upper medulla?
- lower medulla?
- spinal region?
- peripheral region?
- contralateral loss
- ipsilateral loss
- ipsilateral loss
- ipsilateral loss
Describe the motor functions of the cortical gray matter. ***
- motor cortex (primary motor cortex, precentral gyrus, premotor areas)
- concerned with purposeful movement, complex, simultaneous movements (extremities, speech)

- somatotopic organization in primary motor cortex (homunculus)
- areas are conscious level of motor programming (initiation)
Describe the structure and motor functions of the subcortical gray matter. ***
subcortical components
- basal ganglia
- cerebellum
- parts of diencephalon
- parts of brainstem

basal ganglia collaborates with cerebral cortex through a system of feedback loops initiating movement
- contributes to motor programming
- contributes to motor modification

cerebellum collaborates with the
- vestibular system,
- proprioceptive information from the PNS, and
- motor cortex;
responsible for balance, muscle tone, coordination

areas of diencephalon and brainstem also collaborate with above systems in motor programming

- these areas are the unconscious level of motor programming

- motor cortex, basal ganglia, cerebellum, etc. are linked to each other; extensive communication between all of them to program motor commands for coordinated, skilled, volitional movements
Describe the corticobulbar/corticospinal descending tracts (pyramidal system.) ***
- originate at primary motor cortex region in precentral gyrus
- direct route to lower motor neuron (LMN) in brain stem or spinal cord; part of the “final common pathway for motor command”
- gives branches to cerebrum for error correction

- pyramidal system - concerned with initiation of purposeful movements
Describe the rubrospinal, reticulospinal, and vestibulospinal descending tracts (extrapyramidal system.) ***
extrapyramidal system
- rubrospinal,
- reticulospinal, and
- vestibulospinal tracts

- originate from brainstem nuclei to LMN
- important for balance responses, postural control during movement, and some hand and finger movements
What are lower motor neurons? ***
- anterior (ventral) horn cells and cranial nerve nuclei
- motor neurons located in gray matter of brainstem and spinal cord

- the LMN is “final common pathway” for motor commands
- receives direct input from both pyramidal and extrapyramidal systems
- axons travel via peripheral nervous system to skeletal muscles

- final motor command route to muscles for all movement (voluntary and reflexive)
Describe the two types of LMNs. ***
- alpha motor neurons: innervate skeletal muscle

- gamma motor neurons: innervate muscle spindles of skeletal muscles
Describe a motor unit. ***
an alpha motor neuron and all the muscle fibers it innervates

(the picture depicts two motor units)
Special sensory endings (dendritic receptors) for the somatosensory system are located where in the body? ***
- skin, tendons, joints
- organs, blood vessels
- eyes, tongue, nose
(to name a few)
What are the four types of sensation? ***

(She definitely said to know these!!)
- superficial (somatosensory)
- deep (somatosensory)
- visceral
- special senses
What types of sensation does the somatosensory system deal with? ***
- superficial and deep systems

- pain
- temperature
- light touch
- deep touch
- vibration
- proprioception
What structures comprise the somatosensory system? ***
- special sensory receptors and their neuronal connections,
- ascending tracts,
- thalamus,
- primary somatosensory cortex, and
- related association areas
What are receptors? ***
specialized cells for detecting particular changes in both the internal and external environment
Special sensory endings (dendritic receptors) for the somatosensory system are located where in the body? ***
- skin, tendons, joints
- organs, blood vessels
- eyes, tongue, nose
(to name a few)
What are the four types of sensation? ***

(She definitely said to know these!!)
- superficial (somatosensory)
- deep (somatosensory)
- visceral
- special senses
What types of sensation does the somatosensory system deal with? ***
- superficial and deep systems

- pain
- temperature
- light touch
- deep touch
- vibration
- proprioception
What structures comprise the somatosensory system? ***
- special sensory receptors and their neuronal connections,
- ascending tracts,
- thalamus,
- primary somatosensory cortex, and
- related association areas
What are receptors? ***
specialized cells for detecting particular changes in both the internal and external environment
How many types of stimuli is each special receptor capable of detecting? ***
each special receptor is designed to detect a specific type of stimuli
(e.g., Pacinian corpuscle detects pressure; temperature would not affect it)
How is intensity of a stimulus imparted? ***
- intensity of stimuli is signaled by how many action potentials pass along each second
All sensory information is carried via what route, and from which starting point to which ending point? ***
- all sensory information is carried in nerves by action potentials

- from receptors to cell bodies (dorsal root ganglia) of dorsal root to
- posterior horn in spinal cord to
- CNS (and, if indicated, through reflex arc at spinal cord level)
How many types of sensory receptors are there? Name them. ***
- interoceptors
- exteroceptors
- proprioceptors
What are interoceptors? ***
- located deep in viscera and vessels,
- receive stimuli regarding body’s internal changes, such as BP, blood sugar, O2 levels
What are exteroceptors? ***
- a.k.a. cutaneous receptors
- located superficially in skin layers;
- receive stimuli from external environment regarding pain, temperature, light touch, pressure
What are proprioceptors? ***
- located deep in muscle/tendon/joints;
- receive stimuli regarding deep pressure, vibration, position sense and movement sense (kinesthesia)
Which ascending tracts have we been concerned with? ***
- spinothalamic tracts
- dorsal columns
- spinocerebellar tracts
What is the function of the spinothalamic tracts?
- transmits sensory information on pain, temperature, crude touch (know you're being touched, but not sure where)

- crosses in spinal cord (2-3 levels above incoming spinal segment) synapses in thalamus
What is the function of the dorsal columns? ***
- transmit conscious proprioception, vibration, discriminative touch (don’t cross until brainstem)

- travels ipsilaterally in posterior column, crosses in brainstem; synapses in thalamus
What is the function of the spinocerebellar tracts? ***
- transmits unconscious proprioception (movement and position sense)

- dorsal spinocerebellar tract travels ipsilaterally in lateral column; synapses in cerebellum

- ventral spinocerebellar tract crosses and travels contralaterally in lateral column; synapses in cerebellum

- spinocerebellar tracts– not just one place (dorsal & ventral)
What two proprioceptors in the muscles have we looked at? ***
- muscle spindles

- Golgi tendon organs
What is the structure and function of a muscle spindle? ***
- located in muscle belly

- detect muscle length and rate of change in length, allowing
--- fine adjustments with muscle contractions and loading
--- protection of muscle from extreme stretch (tearing)
- when muscle stretches, spindle stretches

consists of:
- special muscle fibers (intrafusal fibers--nuclear chain and nuclear bag)
- 3-5 within a sheath;
- innervated by gamma motor neuron
- entire structure called a spindle
- spindles lie parallel to, within, and attached to regular muscle fibers (extrafusal fibers)
- spindles stimulate with stretch of extrafusal muscle fibers
- when muscle stretches, spindle stretches, and action potentials are fired to DRG then to posterior horn (spinal cord/brain)
--- at spinal cord level, produces stretch reflex response if necessary
--- at higher centers, makes necessary adjustments to muscle loading
How do gamma motor neurons control muscle spindles? ***
- in order for muscle spindle to stay taut and ready to respond to loading/lengthening changes on muscle, spindle must stay contracted, this is controlled by the gamma motor neuron

- gamma motor neuron continuously receives stimuli to contract intrafusal muscle fibers; this keeps spindle taut and ready to react to lengthening or rate of lengthening of extrafusal muscle fibers so that proper sensory feedback is sent to CNS and adjustments are made
How do muscle spindles work? ***
muscle spindles consist of:
- intrafusal fibers innervated by gamma motor neurons (muscle spindle)

- extrafusal fibers innervated by alpha motor neurons (muscle fibers)

To correspond with above picture:

A. During passive stretch, spindles are elongated as the muscle is stretched. This stretch activates the spindle sensory receptors. The arrow indicates action potentials transmitted by the type Ia afferent.

B. Excitation of the alpha motor neuron via the corticospinal neuron results in contraction of the extrafusal muscle fibers. If the gamma motor neurons do not fire when the alpha motor neurons to the extrafusal muscles fire, the intrafusal central region will be relaxed and the afferent neurons inactive. This does not occur in a normal neuromuscular system.

C. Normally, during active muscle contraction, alpha and gamma motor neurons are simultaneously active. The firing of gamma motor neurons causes the ends of intrafusal fibers to contract, thus maintaining the stretch on the intrafusal central region and preserving the ability of the sensory endings to indicate stretch.
Muscle spindle has to reset (quick stretch-muscle contracts; to stretch, needs to be slow)
Describe the structure and function of the Golgi tendon organ. ***
- located in musculotendinous junction

function is to
- detect muscle shortening/tension with muscle contractions
- prevent muscle from exerting so much tension that it avulses from bone

consists of:
- special sensory fiber ending located in musculotendinous regions
- lie in series with muscle fibers
How do contraction and stretching of muscles affect the GTO? ***
when muscle is contracted, GTOs are stretched/stimulated
- action potentials fired to DRG
- then to posterior horn (spinal cord/brain)
- at spinal cord level, inhibits alpha motor neuron of agonist = muscle relaxes

extreme stretching stimulates GTO
- action potentials fired to DRG
- then to posterior horn (spinal cord/brain)
- at spinal cord, results in excitation of alpha motor neuron of agonist = muscle contraction
Why is sensory feedback from all muscles/tendons to the CNS important? ***
proper control of muscle function requires continuous sensory feedback so that proper muscle loading adjustments and muscle responses can be made to the environment (to avoid tears, avulsions, ensure muscles are properly functioning, etc.)
Describe the structure and function of the thalamus. ***
- subcortical gray matter

- majority of sensory information converges in this region

- after synapses; networks with primary sensory cortex and other sensory association areas (cortical gray matter)

(more than a sensory relay station, does have impact on motor movement)
What is the function of the cortical gray matter. ***
- sensory cortex regions (parietal, occipital, temporal lobes)
- somatotopic organization in primary somatosensory cortex

- all association areas network with one another
- integrated sensory information fed to motor regions
List some common motor deficits. ***
(these may appear together or independently of each other)

- paralysis/paresis - loss of movement or weakness
- spasticity: hypertonicity
- rigidity: hypertonicity

- involuntary movements - uncontrolled, purposeless, and/or uncoordinated
- abnormal reflexes

- synergies
- associated reactions
List some common sensory deficits. ***
- analgesia
- hypalgesia
- hyperalgesia
- anesthesia
- hyperesthesia
- paresthesia

- referred pain
- referred visceral pain
Describe some of the mechanisms behind paralysis/paresis - loss of movement or weakness. ***
- precentral gyrus damage – somatotopic organization; contralateral deficits (R CVA-L hemiparesis)

- spinal cord damage – corticospinal tract interrupted; ipsilateral deficits

- peripheral nerve damage – deficits to muscles innervated by that nerve
Describe the mechanisms behind hypertonicity: spasticity. ***
- loss of cortical inhibition over lower level reflexes
- usually accompanies paralysis
- usually damage of corticospinal tract
--- clonus,
--- clasp knife phenomenon (increased resistance of extensors to passive flexion, gives way abruptly if resistance stopped; like closing a pocket knife--it's hard at first, but as you get to the point the blade is almost back in the handle, it quickly snaps in)
Two divisions of hypertonicity (increased tone) ***
- spasticity
--- ususally indicates corticospinal tract disease
--- rate and force dependent (e.g., clasp knife phenomenon)

- rigidity
--- usually indicates basal ganglia disease
--- not rate and force dependent (e.g., lead pipe--same resistance throughout)
Describe the mechanisms behind hypertonicity: rigidity. ***
- loss of cortical inhibition over lower level reflexes

- damage of basal ganglia;
--- tremor in conjunction with rigidity (cogwheel feel to passive movement) or
--- lead pipe rigidity (rigid, but not jerky movement)

- damage to brainstem
--- decerebrate rigidity: extensor tone entire body
--- decorticate rigidity: extensor tone BLE, BUE flex tone
Describe the mechanisms behind involuntary movements: uncontrolled, purposeless, and/or uncoordinated movements. ***
- lesions to cerebellum or extrapyramidal system

- cerebellum; intention tremor, ataxia, dysmetria, dysarthria

- basal ganglia: resting tremor, chorea, athetosis, hemiballismus
Describe the mechanisms behind hyperreflexia ***
- CNS damage/disease
- reflexes no longer overridden
- may become dominant during movement
Two types of abnormal reflexes. ***
- hyperreflexia

- hyporeflexia
Describe the mechanisms behind hyporeflexia ***
- PNS damage/disease
- reflex arc interrupted at spinal cord level
- diminished or absent reflexes
Describe the mechanisms behind synergies. ***
- stereotyped mass pattern of movement of muscle groups instead of isolated movements (total flexion/extension patterns)
- damage to CNS

(Decerebrate, decortical)
Describe the mechanisms behind associated reactions. ***
- abnormal automatic responses of involved limb with action occurring in another part of the body

- damage to CNS

(Example she gave was of something that started with Soqu.... in which a CVA pt has fingers locked in flexion, but if the therapist lifts shoulder above 90 degrees the fingers let go)
What is analgesia? ***
complete loss of pain sensation
What is hypalgesia? ***
decreased sensitivity to pain
What is hyperalgesia? ***
increased sensitivity to pain
What is anesthesia? ***
complete loss of sensation
What is hyperesthesia? ***
increased sensitivity to sensory sensation
What is paresthesia? ***
abnormal sensation such as numbness, prickling, tingling, often without any apparent cause
Describe the mechanism behind referred pain. ***
- pain perceived elsewhere than at its true site (much of pain sensation is referred)

- spinal segment sensory damage – dermatomal distribution
- peripheral nerve sensory damage – cutaneous sensory distribution
Describe the mechanism behind referred visceral pain. ***
- neuronal cell bodies in the posterior horn which receive noxious sensations from afferents in the skin also receive input from nociceptors in the viscera.

- when the visceral nociceptors receive a strong stimulus, cortex often misinterprets the source and identifies the stimulus as coming from a cutaneous region instead of the distant visceral area

- e.g., LUE pain associated with MI
What is "language"? ***
- communication and comprehension of abstract ideas through the interpretations of symbols

symbols can be:
- gestural
- verbal
- written
- conceptual (thinking abstractly)
What is "speech"? ***
- verbal expression of one’s thoughts

- requires the coordination of the larynx, mouth, lips, tongue

- which are controlled by specific cranial nerves in brainstem and cortex regions
Which cerebral hemisphere is dominant for speech and language for the majority of the population? ***
- majority of population is L hemisphere dominant for speech and language function (95%)

- most R handed persons and
- 70% (some studies say 30-40%) of L handed persons are L hemisphere dominant for speech and language
Where are the motor areas for speech and language output? ***
- language output areas
--- speech
--- handwriting
--- gestures

- frontal lobe, premotor area
Where are the motor areas for handwriting and gesturing? ***
- handwriting/gesturing area

- converts language codes from other assoc. areas into complex motor commands for handwriting

- premotor area, very near primary motor area for hand/fingers
Where is the primary motor area for speech? What is it called? ***
- speech area (Broca’s)

- converts language code from other assoc areas into motor commands for speech

- premotor area very near primary motor area for mouth, tongue, throat, and face
Where are the primary motor areas of the cerebral cortex and what are their functions? ***
- primary motor cortex - voluntarily controlled movements
- premotor area - control of trunk and girdle muscles; anticipatory postural adjustments

- supplementary motor area - initiation of movement; orientation planning; bimanual and sequential movements
- Broca's area - motor programming of speech (usually in the left hemisphere only)

- area analogous to Broca's in opposite hemisphere - planning nonverbal communication (emotional gestures, tone of voice); usually in the right hemisphere
Where are the sensory areas for speech and language? ***
- language input areas (tactile, auditory, visual)

- association areas of parietal, temporal lobes, occipital lobe
Where is the tactile association area and what is its function? ***
- parietal lobe: association area very near primary somatosensory area

- interprets objects felt as language
Where is the auditory association area and what is its function? ***
- temporal lobe: Wernicke’s area

- interprets sound as language
Where is the visual association area and what is its function? ***
- occipital lobe: association area

- interprets objects/symbols seen as language
Describe the central speech area, and the flow of information during conversation. ***
consists of
- Broca’s area in the frontal lobe
- Wernicke’s area in the temporal lobe
- interconnecting subcortical bundle of fibers: arcuate fasciculus

- all related motor and sensory association areas are interconnected with white matter pathways
- these pathways travel between the different lobes in the dominant hemisphere
- majority of the population = Left hemisphere
What is aphasia, and what is its cause? ***
- partial or complete loss of speech/language functions

- due to cortical damage to specific language areas:
---reception (comprehension) of language code – loss of auditory or reading comprehension and/or
--- expression of language code – loss of speech, handwriting, or gesturing
What are the four types of aphasia? ***
- expressive aphasia (Broca's aphasia)
- receptive aphasia (Wernicke's aphasia)

- global aphasia
- conduction aphasia
What is expressive aphasia? ***
- a.k.a. Broca’s aphasia

- damage to Broca’s area, motor area for speech, premotor area

- good comprehension of language (written, spoken, gestured)
- difficulty speaking or producing appropriate words
- components of speech articulation are intact (larynx, muscles)

- must communicate with gestures, communication boards, sometimes handwriting
- patient aware of deficit and very concerned or frustrated
What is receptive aphasia? ***
- a.k.a. Wernicke’s aphasia

- damage to Wernicke’s area, sensory association area of temporal lobe

- impaired language comprehension and repetition
- cannot interpret sounds as meaningful language

- verbalization is fluent but doesn’t make sense (“word salad”), rambling
- often patient is unaware
What is global aphasia? ***
- damage to central speech area (Broca’s, Wernicke’s, arcuate fasiculus)

- combination of both expressive and receptive aphasias
- loss of language comprehension

- most severe of aphasias
What is conduction aphasia? ***
- damage to arcuate fasiculus; disconnects Wernicke’s area from Broca’s area
- repetition is severely impaired; naming usually impaired ("Repeat after me." "What is this?")

- comprehension of spoken language is intact
- verbal output is fluent, but can be paraphasic (incoherent, misuse of words)
What is dysarthria? ***
- disorder of the motor components for speech
- slurred speech

- syntax (phrasing or words) intact
- caused by damage to:
--- cerebellum
--- PNI to cranial nerves which innervate larynx, tongue, lips, face
What is agnosia? ***
- “gnosia” – knowledge

- inability to recognize/interpret familiar objects although sensory pathway is intact (via visual, auditory, tactile)

- damage to a specific sensory association area while other association areas are intact
List three types of agnosia. ***
- tactile agnosia
- auditory agnosia
- visual agnosia
What is tactile agnosia and what causes it? ***
- astereognosis

- inability to recognize objects by handling them but can recognize with visual or auditory input

- damage to tactile association area, dominant parietal lobe
What is auditory agnosia and what causes it? ***
- inability to recognize sounds as language but can with vision and tactile

- damage to Wernicke’s area, dominant temporal lobe association area
What is visual agnosia and what causes it? ***
- inability to recognize familiar objects with intact vision but can with auditory and tactile

- damage to dominant occipital lobe association areas
Where are the primary sensory areas of the cerebral cortex? ***
(see photo)
What are the results of lesions to the primary sensory areas of the cerebral cortex? ***
(see photo)
Where are the sensory association areas of the cerebral cortex? ***
(see photo)
What are the results of lesions to the sensory association areas of the cerebral cortex? ***
(see photo)
What is apraxia and what causes it? ***
- “praxia” = action

- inability to carry out a complex or skilled motor act upon request although sensory and motor function are intact

- results from interruptions of pathways between association areas
(e.g., unable to touch nose upon request, but could scratch nose easily if it itched)
What are the results of lesions in the association cortex? ***
(see photo)
What are "the four As" of damage to the cerebral cortex? ***
- aphasia
- apraxia
- agnosia
- asterognosis
What are the three types of memory? ***
- immediate recall
- short-term memory
- long-term memory
What is immediate recall and with what area of the brain is it associated? ***
- sensory memory
retention of information that has been stored for a few seconds
- auditory/visual association areas
What is short-term memory and with what area of the brain is it associated? ***
- retention of unrehearsed information for 30-60 secs
- retention of rehearsed information for several hours to a few days
- temporal lobe region
What is long-term memory and with what area of the brain is it associated? ***
- retention of information for weeks, months, years

- structures of limbic system involved with converting short-term memory to long-term memory
How is the memory of a patient with brain damage frequently affected? ***
- a patient with brain damage to any of the memory areas
(auditory/visual association area, temporal lobe, limbic system) can exhibit memory deficits, often short-term memory deficits.

- these deficits interfere with learning of new skills in rehabilitation
What are three other types of memory? ***
- emotional memory
- declarative memory
- procedural memory
What is emotional memory and with what brain structure is it associated? ***
- related to feelings

- amygdala for fear, structures unknown for other emotions
What is declarative memory and with what brain structure is it associated? ***
- related to facts, events, concepts, locations

- cerebral cortex and hippocampus
What is procedural memory and with what brain structure is it associated? ***
- skilled movements and habits

- frontal cortex, thalamus, basal ganglia