• 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
Reading...
Front

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key

image

Play button

image

Play button

image

Progress

1/128

Click to flip

128 Cards in this Set

  • Front
  • Back
PNS
Orders are sent from CNS through the PNS to voluntary muscles and other effectors in our body.
Sensory Receptors
Specialized to respond to changes in their environment which are called stimuli.
Sensation
Awareness of stimulus
Perception
Interpretation of the meaning of the stimulus
3 ways to classify sensory receptors
1. by the type of stimulus they detect
2. by their body location
3. by their structural complexity
Mechanoreceptors
respond to mechanical force, touch, pressure, vibration and stretch
Thermoreceptors
sensitive to temp changes
Photoreceptors
respond to light energy
Nociceptors
respond to damaging stimuli that result in pain
Exteroceptors
sensitive to stimuli arising outside the body
Interoceptors
also called visceroceptors, respond to stimuliwithin the body, such as from the internal viscera and blood vessels. They monitor chemical changes, tissue stretch, and temp.
Proprioceptors
respond to internal stimuli; however their location is much more restricted. They occur in skeletal muscles, tendons, joints, and ligamnes and in CT coverings of bone and muscle.
Simple Receptors
majority are simple. The simple are modified dendritic endingd of sensory neurons. They are foudn throughout the body and monitor most types of general sensory info.
Complex Receptors
sense organs, localized collections of cells associated with the special senses (vision, hearing, equilibrium, smell and taste)
General Sensory Receptors
(simple receptors) respond to tactile sensation, temp, pain and muscle sense
Free Dentric Nerve Endings
free dendritic endings: everywhere; most abundant in epithelial & connective
tissues
-most are unmyelinated with small diameter (slow)
-respond chiefly to pain & temperature
-examples: Merkel discs in deep skin epidermis & root hair plexuses that
surround hair follicles
Tactile Discs (Merkel Discs)
Unencapsulated; Exteroceptors; Mechanoreceptors (light pressure); slow adapting; in the basal layer of epidermis
Hair Follicle Receptors
Free Nerve Endings that wrap basketlike around fair follicles, are light touch receptors that detect bending of hairs.
Encapsulated Nerve Endings
one or more sensory neuron terminals in
connective tissue capsule; most are mechanoreceptors
Meissner’s corpuscles
touch receptors in dermal papillae
Pacinian corpuscles
deep pressure receptors in hypodermis
Ruffini’s corpuscles
deep, continuous pressure receptors in the dermis,
hypodermis & joint capsules
muscle spindles
proprioceptors in skeletal muscle perimysium; cause muscle
contraction to counteract stretch
Golgi tendon organs
proprioceptors in tendons (close to muscle insertion);
cause muscle relaxation (inhibitory to prevent damage due to overstretching)
joint kinesthetic receptors
proprioceptors within articular capsules in
synovial joints; several receptor types that monitor joint function
Somatosensory System
Part of the sensory system serving the body wall and limbs. It receives input from exteroceptors, proprioceptors, and interoceptors.
Three levels of neural integration operate in the somatosensory system
1. Receptor level- sensory receptors
2. Circuit level- ascending pathways
3. Perceptual level- neuronal circuits in the cerebral cortex
Processing at Receptor level
1. the stimulus energy must match the specifity of the receptor
2. The stimulus must be applied within a sensory receptors receptive field.
3. The stimulus energy must be concerted into the energy of a graded potential called a receptor potential by transduction
4. A generator potential in the associated sensory neuron must reach threshold so that voltage gated sodium channels on the axon are opened and nerve impulses are generated and propagated to the CNS.
Adaptation
Change in sensitivity in the presence of a constant stimulus
Phasic Receptors
fast adapting often giving burst of impulses at the beginning and at the end of the stimulus. Act to report changes in the internal or external environment. Ex. pacinian and meissners corp.
Tonic Receptors
provide a sustained response with little or no adaptation. Nociceptors and proprioceptors are tonic receptors b/c of the protective importance of their info.
Circuit Level- The second level of integration:
The Task:
Circuit Level- The second level of integration:
The Task:
task is to deliver impulses to the appropriate region of the cerebral cortex for stimulus localization and perception.
Ascending Sensory Pathways consist of a chain of 3 neurons...
-ascending pathways conduct sensory impulses upward
-first-order neurons: conduct impulses from sensory receptors to brain stem or spinal cord
-second-order neurons: conduct impulses from spinal cord or medullary nuclei to the thalamus or cerebellum
-third-order neurons: conduct impulses from the thalamus to the somatosensory cortex
Processing at the Circuit level of Integration:
Processing at the Circuit level of Integration:
-The axons of the first-order sensory neurons, whose cell bodies are in the dorsal root or cranial ganglia, link the receptors and circuit levels of processing.
-Central processes of first-order neurons branch diffusely when they enter the spinal cord. Some branches take part in local spinal cord reflexes, and others synapse with second-order sensory neurons which then synapse with the third-order sensory neurons that take the message to the cortex of the cerebrum.
Perceptual Level- The third level of integration:
The Task:
Perceptual Level- The third level of integration:
The Task:
-The ability to identify and appreciate sensations depends on the specific location of the target neurons in the sensory cortex, not on the nature of the message
-Each sensory fiber is analogous to a labeled line that tells the brain who is calling, a taste bud, or a pressure receptor, and from where.
-The brain always interprets the activity of a specific sensation, no matter how it is activated.
Projection in processing at perceptual level:
Projection in processing at perceptual level:
-The exact point in the cortex always refers to "where", regardless of how it is activated. This is a phenomenon called projection.
Processing at Receptor Level:
Processing at Receptor Level:
-Transduction by sensory receptors: a stimulus alters permeability of membrane receptors, leading to a local graded potential or receptor potential (like EPSP)… if the receptor is a separate cell (nonneuron), depolarization is called a generator potential
-If the receptor potential is at or above the threshold, an action potential will be generated & propagated to the CNS
-Adaptation by sensory receptors: some receptors (pressure, touch, smell) become insensitive to the same stimuli over time (don’t notice feel of clothing after some time) while others do not adapt (nociceptors & proprioceptors need to continually react to stimuli)
Processing at Circuit Level:
posterior column-medial lemniscus pathway:
Processing at Circuit Level:
posterior column-medial lemniscus pathway:
-impulses conveyed to cerebral cortex via posterior column of spinal cord & medial lemniscus of brain stem (relayed by thalamus)
-transmit discriminative touch, pressure, vibration, & conscious proprioception impulses, & also arousal (to RAS)
Processing at Circuit Level:
anterolateral (spinothalamic) pathway:
anterolateral (spinothalamic) pathway:
-impulses conveyed to cerebral cortex via anterior & lateral spinothalamic tracts within anterior & lateral columns of spinal cord (also relayed by thalamus)
-transmit pain, temperature (lateral) & itch, tickle, pressure & coarse touch (anterior) impulses
-involved with emotional aspects of perception & some higher level motor reflexes (orienting to stimulus)
Processing at Circuit Level:
spinocerebellar tracts:
spinocerebellar tracts:
-convey information from proprioceptors on one side of the body to the same side of the cerebellum to coordinate skeletal muscle activity (unconscious sensation) & maintain posture & balance
Processing at the Perceptual Level:
Perception Involves:
Processing at the Perceptual Level:
Perception involves:
awareness of stimuli, their origin & discrimination of their characteristics
• Localization & modality of sensory inputs are begun as tracts reach the thalamus, but most processing occurs in the somatosensory cortex
Main aspects of sensory detection:
Main aspects of sensory detection:
-perceptual detection
-magnitude estimation
-spatial discrimination
-feature abstraction
-quality discrimination
-pattern recognition
Main aspects of sensory detection:
perceptual detection:
perceptual detection: detection of stimulus
Main aspects of sensory detection:
magnitude estimation:
magnitude estimation: how much of the stimulus
Main aspects of sensory detection:
spatial discrimination:
spatial discrimination: site or pattern of stimulus
Main aspects of sensory detection:
feature abstraction:
feature abstraction: neuron or circuit is tuned to one feature over others
Main aspects of sensory detection:
quality discrimination:
quality discrimination: differentiation of submodalities (parts) of sensation
Main aspects of sensory detection:
pattern recognition:
pattern recognition: find patterns in complex stimuli
How are Pain Receptors activated?:
How are Pain Receptors activated?:
-by extremed of pressure and temperature as well as a veritable soup of chemicals released from injured tissue.
-Histamine, K+, ATP, acids, and bradykinin are among the most potent pain-producing chemicals.
-All of these chemicals act on small-diamteter fibers
When you cut you finger you may notice sharp then burning pain...
When you cut you finger you may notice sharp then burning pain...
-Sharp pain is carried by small myelinated A delta fibers, while burning pain is carried more slowly by small un-myelinated C fibers.
-Both types of fibers release the neurotransmitters glutamate and substance P, which activate second-order sensory neurons. Acons from these second-order neurons ascend to the brain via the spinothalamic tract and other aterolateral pathways.
If you cut your finger while being attacked, you may not notice the pain...
If you cut your finger while being attacked, you may not notice the pain...
-The brain has its own pain-suppressing analgesic systems in which the endogenous opioids (endorphines and enkephalins) play a key role.
-Descending cortical and hypothalamic pain-suppressing signals are relayed through various nuclei in the brain stem including the periaqueductal gray matter of the midbrain.
-Descending fibers activate interneurons in the spinal cord, which release the opioid neurotransmitters called enkephalins. Enkephalins are inhibitory neurotransmitters that quash the pain signals generated by the nociceptive.
Nerves & Associated Ganglia:
Nerve:
Nerves & Associated Ganglia:
Nerve:
-cordlike organ of PNS consisting of bundles of axons enclosed in layers of connective tissue
Nerves & Associated Ganglia:
endoneurium
Nerves & Associated Ganglia:
endoneurium:
-each axon enclosed in endoneurium
Nerves & Associated Ganglia:
perineurium:
perineurium:
-bundles of fibers (fascicles) enclosed in perineurium
Nerves & Associated Ganglia:
epineurium
epineurium:
-bundles of fascicles enclosed in epineurium
Nerves & Associated Ganglia:
sensory (afferent) nerves:
sensory (afferent) nerves:
-carry impulses toward CNS
Nerves & Associated Ganglia:
motor (efferent) nerves:
motor (efferent) nerves:
-carry impulses away from CNS
Nerves & Associated Ganglia:
mixed nerves:
contain both sensory & motor fibers (can be somatic &/or autonomic)
mixed nerves:
-contain both sensory & motor fibers (can be somatic &/or autonomic)
Nerves & Associated Ganglia:
peripheral nerves classified as:
peripheral nerves classified as:
-spinal nerves or cranial nerves
Nerves & Associated Ganglia:
ganglia:
ganglia:
-collections of neuron cell bodies associated with nerves in PNS
Regeneration of Nerve Fibers:
Regeneration of Nerve Fibers:
-in general, mature neurons are amitotic (do not divide)
-if cell body remains intact, regeneration is possible
-following injury, the two ends of neuron surrounding site of injury seal off & swell from accumulation of materials
-Wallerian degeneration: the axon distal to the site of injury & its myelin sheath begins to disintegrate (debris cleaned up by macrophages & Schwann cells)
-Schwann cells proliferate in response to macrophage signals, & express cell adhesion molecules & release growth factors to stimulate axonal growth... then, they guide axon extensions across the gap (form regeneration tube to bridge gap) & remyelinate the axon
-The greater the distance between broken axon ends, the less the chance of regeneration
Cranial Nerves:
Cranial Nerves:
-12 pairs
-The first two pairs atttach to the forebrain, and the rest are associated with the brain stem.
-Other than the vagus nerves which extend into the abdomen, cranial nerves serve only head and neck structures.
Cranial Nerves:
Olfactory Nerve:
I.Olfactory Nerve (cranial nerve I)
: sensory for smell

Cranial Nerves:
Optic Nerve
II.Optic Nerve (cranial nerve II)
: sensory for vision

Cranial Nerves:
Oculomotor Nerve
III.Oculomotor Nerve (cranial nerve III)
:
motor for eyeball movement (4 of the 6 extrinsic eye muscles) & upper eyelid movement (sensory for proprioception in extrinsic eye muscles)

Cranial Nerves:
Trochlear Nerve
IV. Trochlear Nerve (cranial nerve IV)
:
motor for eyeball movement (superior oblique muscle) (sensory for proprioception in superior oblique muscle)
Cranial Nerves:
Trigeminal Nerve
V. Trigeminal Nerve (cranial nerve V)
:
sensory for touch, pain & thermal sensation in face; motor for chewing

Cranial Nerves:
Abducens Nerve
VI. Abducens Nerve (cranial nerve VI)
:
motor for eyeball abduction (lateral rectus muscle) (sensory for proprioception in lateral rectus muscle)

Cranial Nerves:
Facial Nerve
VII. Facial Nerve (cranial nerve VII)
:
sensory for taste (anterior 2/3 of tongue); motor for contraction of facial muscles and activity of lacrimal, nasal, palatine & salivary glands

Cranial Nerves:
Vestibulocochlear Nerve
VIII. Vestibulocochlear Nerve (cranial nerve VIII)
:
sensory for hearing (cochlear nerve) & equilibrium (vestibular nerve)

Cranial Nerves:
Glossopharyngeal Nerve
IX. Glossopharyngeal Nerve (cranial nerve IX)
:
sensory for taste (posterior 1/3 of tongue); motor for swallowing (elevation of larynx & pharynx)

Cranial Nerves:
Vagus Nerve
X. Vagus Nerve (cranial nerve X)
:
-sensory for taste (epiglottis), baroreception & chemoreception in blood vessels, and sensation from thoracic & abdominal organs; motor for regulation of heart rate, breathing, swallowing/speech & digestive system activity

Cranial Nerves:
Accessory Nerve
XI. Accessory Nerve (cranial nerve XI)
:
-motor for head & neck movement and swallowing (sensory for proprioception in sternocleidomastoid & trapezius muscles)

Cranial Nerves:
Hypoglossal Nerve
XII. Hypoglossal Nerve (cranial nerve XII)
:
-motor for speech & swallowing (sensory for proprioception in tongue muscles)
Easy way to remember the cranial nerves in order:
Easy way to remember the cranial nerves in order:
-On Occasion, Our Trusty Truck Acts Funny- Very Good Vehicle Anyhow.
Spinal Nerves are formed by...
Spinal Nerves are formed by...
-the fusion of ventral (motor) and dorsal (sensory) roots.
Cranial Nerves:
Cranial Nerves:
-most cranial nerves are mixed nerves
-however, two nerve pairs (the olfactory and optic) associated with special sense organs are generally considered purely sensory.
Two Cranial Nerves considered purely sensory...
Two Cranial Nerves considered purely sensory...
-Olfactory and Optic
-There cell bodies are located within their respective special sense organs.
-In other cases of sensory neurons contributing to cranial nerves (V<VII< IX< and X), the cell bodies are located in the cranial sensory ganglia just outside the brain.
-Some cranial nerves have a single sensory ganglion, others have several and some have none.
Several of the mixed cranial nerves contain both somatic and autonomic motor fibers:
Several of the mixed cranial nerves contain both somatic and autonomic motor fibers:
-hence they serve both skeletal muscles and visceral organs.
-Except for some autonomic motor neurons located in ganglia, the cell bodies of motor neurons contributing to the cranial nerves are located in the ventral gray matter regions ( nuclei) of the brain stem.
How many pairs of Spinal Nerves?:
How many pairs of Spinal Nerves?:
31 pairs
-8 pairs of cervical
-12 pairs of thoracic
-5 pairs of lumbar
-5 pairs of sacral
-1 pair of coccygeal
Spinal Nerves:
ventral roots:
Spinal Nerves:
ventral roots:
-contain motor (efferent) fibers arising from the anterior horn & extending to skeletal muscle fibers
Spinal Nerves:
dorsal roots:
Spinal Nerves:
dorsal roots:
contain sensory (afferent) fibers arising from sensory neurons in the dorsal root ganglia; conduct impulses from sensory receptors to spinal cord
-spinal nerves are short (1-2 cm); branch into smaller dorsal ramus, larger ventral ramus & tiny meningeal branch to meninges & blood vessels
-thoracic spinal nerves have rami communicantes with autonomic (visceral) fibers
Spinal Nerves:
dermatomes:
dermatomes:
-areas of skin innervated by individual spinal nerves
Spinal Nerves:
Hilton’s Law:
Hilton’s Law:
-any nerve serving a muscle that produces movement at a joint also innervates the joint & the skin over the joint
Innervation of Specific Body Regions:
Innervation of Specific Body Regions:
-The spinal nerve rami and their main branches supply the entire somatic region of the body (skeletal muscles and skin) from the neck down.
-The dorsal rami supply the posterior body trunk.
-The thicker ventral rami supply the rest of the trunk and the limbs.
Innervation of Specific Body Regions:
Difference b/w Roots and Rami:
Innervation of Specific Body Regions:
Difference b/w Roots and Rami:
-Roots lie medial to and form the spinal nerves, and each root is strictly sensory or motor.
-Rami lie distal to and are lateral branches of the spinal nerves and, like spinal nerves, carry both sensory and motor fibers.
Innervation of Specific Body Regions:
Ventral Rami of the Spinal Nerves:
Innervation of Specific Body Regions:
Ventral Rami of the Spinal Nerves:
-Except for T2-T12, all ventral rami branch and joint one another lateral to the vertebral column, forming complicated interlacing nerve networks called nerve plexuses.
Innervation of Specific Body Regions:
Nerve Plexuses:
Innervation of Specific Body Regions:
Nerve Plexuses:
-interlacing nerve networks (lateral to spinal cord) from ventral rami of groups of spinal nerves serving similar body regions
- muscles of the anterolateral thorax & abdominal wall served by spinal nerves T1-T12 as intercostal nerves, with cutaneous branches to skin
Innervation of Specific Body Regions:
cervical plexus:
Innervation of Specific Body Regions:
cervical plexus:
-spinal nerves C1-C5; supplies skin & muscles of head, neck & superior part of shoulders & chest
-phrenic nerve: serves diaphragm for breathing
Innervation of Specific Body Regions:
brachial plexus:
Innervation of Specific Body Regions:
brachial plexus:
spinal nerves C5-T1; supplies shoulders & upper limbs
-branches: roots (ventral rami of C5-T1), trunks (upper, middle, lower), divisions (anterior & posterior) & cords (lateral, medial & posterior)
-nerves: musculocutaneous, median, ulnar, radial & axillary
Innervation of Specific Body Regions:
lumbar plexus:
Innervation of Specific Body Regions:
- lumbosacral plexus: lower limb; branches to pelvis, abdomen & buttocks
lumbar plexus:
spinal nerves L1-L4; supplies anterior abdominal wall, external genitals & part of lower limbs
-femoral nerve: serves muscles of anterior upper leg (quadriceps) & skin of anterior & medial lower leg
-obturator nerve: serves adductor muscles of medial thigh
Innervation of Specific Body Regions:
sacral plexus:
Innervation of Specific Body Regions:
sacral plexus:
-spinal nerves L4-S4; supplies buttocks, perineum & lower limbs
-sciatic nerve: serves entire leg except anteromedial thigh (longest & thickest nerve in body); branches to tibial & common fibular nerves just above knee
Innervation of Specific Body Regions:
coccygeal plexus:
Innervation of Specific Body Regions:
coccygeal plexus:
-spinal nerves S4-Co; supplies small area of skin in coccygeal region
Innervation of Specific Body Regions:
Back:
Innervation of Specific Body Regions:
Back:
-following neat, segmented plan, Via its several branches, each dorsal ramus innervates the narrow strip of muscl and skin in line with its emergence point from the spinal column.
Innervation of Specific Body Regions:
Anterolateral Thorax and Abdominal Wall:
Innervation of Specific Body Regions:
Anterolateral Thorax and Abdominal Wall:
-Only in the thorax are the ventral rami arranged in a simple segmental pattern corresponding to that of the dorsal rami.
-Intercostal nerves- the ventral rami od T1-T12 mostly course anteriorly, deep to each rib, as the intercostal nerves. Along their course, these nerves give off cutaneous branches to the skin.
-Subcostal Nerve- Two thoracic nerves are unusual: the tiny T1 and T12, which lies inferior to the twelfth rib, making it a subcostal nerve.
-The intercostal nerves and their branches supply the intercostal muscles lying between the ribs, the muscle and skin of the anterolateral thorax, and most of the abdominal wall.
Innervation of Specific Body Regions:
Cervical Plexus and Neck:
Innervation of Specific Body Regions:
Cervical Plexus and Neck:
- buried deep in the neck under the sternocleidomastoid muscle, the looping cervical plexus is formed by the ventral rami of the first four cervical nerves.
-most branches are cutaneous nerves that supply only skin.
-They transmit sensory impulses from the skin of the neck, the ear, the back of the head, and the shoulder. Other branches innervate muscles of the anterior neck.
-Phrenic Nerve- receives fibers from C3-C5. runs inferiorly through the thorax and supplies both motor and sensory fibers to the diaphragm.
Innervation of Specific Body Regions:
Brachial Plexus and Upper Limb:
Innervation of Specific Body Regions:
Brachial Plexus and Upper Limb:
-partly in neck and partly in axilla.
-give rise to almost all the nerves that innervate the upper limb.
-formed by intermixing of ventral rami od C5-C8 and most of the T1 ramus.
-It often receives fibers from C4, T2 or both.
Innervation of Specific Body Regions:
4 major groups of branches in Brachial Plexus:
Innervation of Specific Body Regions:
4 major groups of branches in Brachial Plexus:
-"Really Tired? Drink Coffee"
-From medial to lateral,
1. the ventral rami misleadingly called roots;
2. trunks, which form;
3. divisions, which form;
4. cords.
Innervation of Specific Body Regions:
The five roots of the brachial plexus...
Innervation of Specific Body Regions:
The five roots of the brachial plexus...
-lie deep to the sternocleidomastoid muscle. At the lateral border of that muscle, the roots unite to form upper, middle and lower trunks, each of which divides almost immediately into an anterior and posterior division.
-These divisions which generally indicate which fibers serve the front or back of the limb, pass deep to the clavicle and enter the acilla, where they give rise to three large fiber bundles called the lateral medical and posterior cords.
Innervation of Specific Body Regions:
axillary nerve:
Innervation of Specific Body Regions:
axillary nerve:
- branch off the posterior cord and runs posterior to the surgical neck of the humerus. It innervates the deltoid and teres minor muscles and the skin and joint capsule.
Innervation of Specific Body Regions:
musculocutaneous nerve:
Innervation of Specific Body Regions:
musculocutaneous nerve:
-the major end branch of the lateral cord, courses inferiorly in the anterior arm, supplying motor fibers to the biceps brachii and brachialis muscles. Distal to the elbow, it provides for cutaneous sensation of the lateral forearm.
Innervation of Specific Body Regions:
Median Nerve:
Innervation of Specific Body Regions:
Median Nerve:
-descends through the arm to the anterior forearm, where it gives off branches to the skin and to most flexor muscles. On reaching the hand, it innervates five intrinsic muscles of the lateral palm. The median nerve activates muscles that pronate the forearm, flex the wrist and fingers, and oppose the thumb.
Innervation of Specific Body Regions:
Ulnar Nerve:
Innervation of Specific Body Regions:
Ulnar Nerve:
-branches off the medial cord of the plexus. Descends along...p.505
Innervation of Specific Body Regions:
Ulnar Nerve:
Radial Nerve:
Innervation of Specific Body Regions:
Ulnar Nerve:
Radial Nerve:
p. 505
Somatic Motor Pathways:
Levels of Motor Control:
Somatic Motor Pathways:
Levels of Motor Control:
-some lower-level motor control is mediated by reflex arcs, but complex motor activities appear to be regulated by fixed-action patterns (stereotyped sequential motor actions triggered internally or by environmental stimuli)
Somatic Motor Pathways:
Levels of Motor Control:
Segmental level:
Somatic Motor Pathways:
Levels of Motor Control:
Segmental level:
-segmental circuits of spinal cord
-Segmental circuits activate anterior horn segments of the spinal cord to stimulate a specific group of muscle fibers
-Circuits controlling locomotion & common motor activity are called central pattern generators (CPGs)
Somatic Motor Pathways:
Levels of Motor Control:
Projection level:
Somatic Motor Pathways:
Levels of Motor Control:
Projection level:
cortical motor areas that produce the direct (pyramidal) system & indirect (extrapyramidal or multineuronal) system.
-axons of the neurons at this level project to the spinal cord & help control both reflex & fixed-action pattern activities, and produce voluntary movement
Somatic Motor Pathways:
Levels of Motor Control:
Programs & Instructions Level:
Somatic Motor Pathways:
Levels of Motor Control:
Programs & Instructions Level:
-neurons in the basal nuclei of the cerebrum and of the cerebellum (precommand areas) that regulate motor activity
-Involved in starting & stopping movements, coordinating movements with posture, blocking unwanted movements & maintaining muscle tone
Somatic Motor Pathways:
Cerebellum:
Somatic Motor Pathways:
Cerebellum:
center for sensorimotor integration & control, correcting errors in muscle activity, & fine-tuning motor activity
-damage to the cerebellum results in disorders of synergy & muscle tone, disturbances of equilibrium & speech disorders
Somatic Motor Pathways:
Basal Nuceli:
Somatic Motor Pathways:
Basal nuclei:
-receive inputs from all cortical areas & send output to the premotor & prefrontal cortex to coordinate more complex motor activities
Organization of Upper Motor Neuron Pathways:
cortical motor areas:
Organization of Upper Motor Neuron Pathways:
cortical motor areas:
-that produce the direct (pyramidal) system & indirect (extrapyramidal or multineuronal) system
Organization of Upper Motor Neuron Pathways:
Organization of Upper Motor Neuron Pathways:
Organization of Upper Motor Neuron Pathways:
Direct Motor Pathways:
Organization of Upper Motor Neuron Pathways:
Direct Motor Pathways:
-lateral corticospinal tracts: conveys nerve impulses from motor cortex to skeletal muscles on opposite side of the body for precise, voluntary movements of hands & limbs
-anterior corticospinal tracts: conveys nerve impulses from motor cortex to skeletal muscles on opposite side of the body for movements of axial skeleton
-corticobulbar tracts: conveys nerve impulses from motor cortex to skeletal muscles of the head & neck for precise, voluntary movements
Organization of Upper Motor Neuron Pathways:
Indirect (extrapyramidal) tracts:
Organization of Upper Motor Neuron Pathways:
Indirect (extrapyramidal) tracts:
-all somatic motor tracts other than direct motor pathways
-axons of UMN that carry impulses from indirect pathways descend from various nuclei of the brain stem into 5 major tracts of spinal cord & terminate on local circuit neurons or LMNs
-rubrospinal, tectospinal, vestibulospinal, lateral & medial reticulospinal tracts
Reflexes:
Reflexes:
-somatic reflexes: lead to contraction of skeletal muscles
-autonomic (visceral) reflexes: lead to responses from smooth muscle, cardiac muscle & glands
Reflex Arc:
Reflex arc:
-sensory receptor:
-sensory neuron:
-integration center:
-motor neuron:
-effector:
-general reflex types:
-omonosynaptic reflex:
-polysynaptic reflex:
-ipsalateral reflex:
-contralateral reflex:
Reflex arc:
sensory receptor:
Reflex arc:
sensory receptor:
distal end of sensory neuron; responds to stimulus
Reflex arc:
sensory neuron:
Reflex arc:
sensory neuron:
-carries impulse from receptor to axon terminals in gray matter of spinal cord (or brain stem)
Reflex arc:
integration center:
Reflex arc:
integration center:
within CNS gray matter, signal travels across synapse or through interneuron, generating a response
Reflex arc:
motor neuron:
Reflex arc:
motor neuron:
-response impulse is sent from sensory neuron or interneuron through motor neuron to effector
Reflex arc:
effector:
Reflex arc:
effector:
-muscle or gland that carries out response (reflex)
Reflex Arc:
general reflex types:
Reflex Arc:
general reflex types:
-monosynaptic reflex: involves only 2 neurons (sensory & motor) & one synapse
-polysynaptic reflex: involves more than 2 neurons (sensory, motor & interneurons) & more than one synapse
-ipsalateral reflex: sensory neurons enter & motor neurons exit spinal cord on same side
-contralateral reflex: sensory neurons enter & motor neurons exit spinal cord on opposite sides
somatic spinal reflexes:
stretch reflex:
somatic spinal reflexes:
-stretch reflex:
-causes contraction of skeletal muscle in response to muscle stretching
-sensory receptors are muscle spindles
somatic spinal reflexes:
tendon reflex:
somatic spinal reflexes:
tendon reflex:
-causes muscle relaxation in response to increasing muscle tension (to prevent tendons from tearing)
-sensory receptors are (Golgi) tendon organs
somatic spinal reflexes:
flexor (withdrawal) reflex:
somatic spinal reflexes:
flexor (withdrawal) reflex:
-causes muscle contraction to move body region away from painful stimulus
-plantar flexion reflex: curling under of toes in response to stimulation of lateral outer margin of toe
-damage to descending motor pathways causes great toe extension (Babinski sign), although a normal response in infants
somatic spinal reflexes:
crossed extensor reflex:
somatic spinal reflexes:
crossed extensor reflex:
-works with withdrawal reflex to maintain balance
-contraction of extensors on opposite side of body to compensate for withdrawal (contralateral reflex)
What information does your nervous system need in order to smoothly coordinate the activity of your skeletal muscles?
What information does your nervous system need in order to smoothly coordinate the activity of your skeletal muscles?
-Two types of info about the current state of a muscle are key.
-First, the nervous sustem needs to know the length of the muscle. The muscle spindles found in the skeletal muscles supply this info.
-Second, it needs to know the amount of tension in the muscle and its associated tendons. Golgi tendon organs provide this info.
Functional Anatomy of Muscle Spindles:
Functional Anatomy of Muscle Spindles:
p.515