Patho Neuro 43-49

Front 1

Purpose of the Nervous system

Which is done by?

Back 1

• rapid communication between sensory→central processing→ function responses
• multiple neurotransmitter molecules and even more receptors for neurotransmitters

Front 2

3 principle units

Back 2

CNS: central nervous system
- PNS: peripheral nervous system
- ANS: autonomic nervous system

Front 3

CNS INCLUDES?

Primary function of the CNS

Back 3

Brain and spinal cord

receiving sensory input and creating appropriate responses in muscles, glands and peripheral nerves

Front 4

CNS
Shielded by ____(3) things
Interacts with ?
Meninges (3) layers
___circulates within the ____

Back 4

•Shielded by meninges, CSF (cerebrospinal fluid), and blood-brain barrier (glial cells)
•Interacts with neurons in PNS with synapses in spinal cord horns and cranial nerve ganglia
•Support/protect → meninges: 3 layers
odura mater
oarachnoid
opia mater (most inner)
•CSF circulates within the subarachnoid space

Front 5

Describe the 3 layers of the meninges

Back 5

• Dura mater- thick, tough, outermost collagenous layer - folds between Cerebrum/cerebellum (tentorium) and between cerebral hemispheres (falx)
• Arachnoid and pia - thin, delicate layers (web-like) → pia in between gyri (folds)- into sulci
• Dura extends over spinal cord - cauda equine and filum terminale
• CSF (made by appendable cells)- produced by choroid plexus (lateral and third ventricle) - steady rate production
• Absorbed in arachnoid villi (tufts in the superior sagittal sinus)

Front 6

Blood-brain barrier

Back 6

• Blood-brain barrier - maintained by glial cells (astrocytes) → foot processes contact brain capillaries and regulate transport across capillary endothelium.

Front 7

Brain Telenecephalon 3 parts

Back 7

•Cerebral hemispheres - divided by longitudinal fissure
•Outermost - cerebral cortex (gray matter) - gyri (ridges) and sulci (grooves)
•Fissures: deeper depressions

Front 8

Anatomoic locations associated with particular brain functions
lobes
Language
memory
basal ganglia--->

Back 8

• Occipital lobe, temporal lobe, parietal lobe, frontal lobe
• Language → Wernicke → expression: dominant/ Broca→ speech
• Memory and emotion - limbic system
• Basal ganglia - large masses of gray matter deep within cerebral hemispheres → caudate nucleus, globus pallidus, subthlamus, substantia nigra → coordination and initiation of movement

Front 9

Dienchepholon---?
parts?

Back 9

Diencephalon - connection between upper brainstem and cerebral hemispheres
• Origin of cranial nerves I (olfactory) and II (optic)
• 4 principle structures:
o thalamus
o hypothalamus
o epithalamus
o ventral thalamus

Front 10

Colonies?

Back 10

group of nerve cells in the CNS: nuclei
Group of nerve cells in the PNS: ganglia

Front 11

Hypothalamus (anatomy)
Anterior pituitary gland ?
Hypothalamus function?

Back 11

• Hypothalamus → inferior portion extends downward to form the posterior pituitary gland (neurohypophysis)
• Anterior pituitary gland: adenohypophysis: glandular tissue responsive to releasing/ inhibiting hormones secreted from the hypothalamus
• Hypothalamus also center for ANS functions: sleep, temperature, appetite, sex drive
o Senses and responds to changes in blood pressure, osmolarity, O2 and CO2 levels, pH

Front 12

Cerebellum includes?
Located
Separated from
Main function?

Back 12

Metencephalon: with pons:
o located in posterior fossa
o separated from cerebrum by tentorium
o Main functions → coordination sna smooth movements (posture and balance), receives sensory input from proprioceptors in joints and muscles and vestibular apparatus (position of head, movement)

Front 13

Brainstem aka
3 parts?
Transmission of
contains vital centers for
origination of ?
which crainal nerves don't come off here?

Back 13

Myelencephalon)
o stalk of neural tissue between spinal cord and diencephalons
o 3 parts
• midbrain, pons and medulla oblongata
o transmission of impulses from brain⇐⇒spinal cord
o also contains vital centers for respiratory and cardiovascular control
o origination of 10 of the 12 cranial nerves nuclei - not olfactory (I) and optic (II)
o CNIII (oculomotor) prone to compression from increased ICP → dilated/ nonRx pupils
o All of the 3-12 cranial nerves are in the medulla and pons expect for 1 and 2 that come off higher

Front 14

Pons "____"

Back 14

• Pons- “bridge”: connects medulla and midbrain-asc/desc tracts and respiratory centers

Front 15

Medulla is where?

Back 15

decussation of fibers/tracts crossing over occur

o dorsal→sensory tracts corticospinal→ motor
o orgin of CN (VI→XII)

Front 16

Spinal Cord
Conveys?
Mediates?
___inches long....ends about____level
cross section looks like___

Back 16

• Conveys impulses from the brain⇐⇒ 31 pairs of spinal nerves that innervate muscles glands and sensory organs
• Mediates spinal reflexes involved in posture
• 18 inches long- ends about L1-2 level
• Cross section→ butterfly pattern
(Fig 43-17, page 1061)

Front 17

Horns ---->

White matter -->

Back 17

• “horns” → ventral (motor) and dorsal (sensory) and lateral (sympathetic)
o Consists of cell bodies, synapses and small interneurons

• White matter → myelinated tracts traveling to/from brain/body
o posterior (dorsal) , anterior and lateral columns

Front 18

Sensory tracts:

Motor tracts:

Spinal nerves:

Back 18

• Sensory tracts → dorsal column and anterior- lateral spinothalamic tracts
o Afferent: signals going to brain

•Motor tracts→corticospinal, rubrospinal, vestibulospinal tracts
oEfferent → signals coming from brain

• Spinal nerves: split and make contact with spinal cord → ventral and dorsal roots
o Dorsal roots→ sensory info (afferent)
o Ventral roots→ motor info (efferent)
•Sensory root cell bodies located in dorsal root ganglion

Front 19

PNS
___pairs of spinal nerves
Myelinated by ____cells (differ from CNS which are ____
Gangila___
Nuclei____
expections is the _____

Back 19

Peripheral Nervous System
• 31 pairs of spinal nerves and 12 cranial nerves
• Myelinated by Schwann cells (diff. from oligodendocytes → myelinate CNS & CN I & II)
• Ganglia→groups of cell bodies in PNS
• nuclei→ group of cell bodies in CNS
o exception: basal ganglia
• Serves both afferent and efferent functions (somatic and autonomic)

Front 20

Spinal nerves
Pairs named after vertebral segment

Back 20

o 8 cervical
o 12 thoracic
o 5 lumbar
o 5 sacral
o 1 coccygeal

Front 21

Spinal Nerves:
typically travel? Exception?
At the plexus the fibers _____
Dermatome:
Sensory?
Motor?

Back 21

• Typically travel a distance from the spinal cord and then merge into plexus
• Exception: T2 through T12
• At the plexus the fibers recombine into different groups and emerge as peripheral nerve
• 5 plexuses: cervical, brachial, lumbar, sacral and coccygeal
• Dermatome: segment of the body innervated by a spinal nerve.
• Sensory root (dorsal)
• Motor root (ventral)

Front 22

ANS
Composed of
Mediated_____
Sympathetic neurons leaving spinal cord --->

Back 22

• Composed of neurons of both the CNS and PNS
• Mediate automatic and involuntary functions - innervates visceral organs & blood vessels
• Sympathetic neurons leaving the spinal canal → converge on chain of ganglia running parallel to both sides of spinal cord (some synapse here and others travel through) → Preganglionic → post-ganglionic neurons (travel to target cell/organ)

Front 23

•Pre-ganglionic neuro-transmitter
•Post-ganglionic neuro-transmitter

Back 23

• Pre-ganglionic neuro-transmitter→ acetylcholine (both PSNS & SNS)
• Post-ganglionic neuro-transmitter→ SNS (norepinephrine) PSNS (acetylcholine)
• ACH also is neurotransmitter for motor neurons for skeletal muscle (diff. receptor)
• ACH receptor for skeletal muscle (nicotinic) autonomic (muscarinic)

Front 24

Convergance

Divergence

Back 24

Divergence→ one pre-synaptic neuron affects multiple post-synaptic neurons
Convergence→ multiple pre-synaptic neurons affect single post-synaptic neuron

Front 25

2 principle cell types

Back 25

• Neurons: generate and transmit nerve impulses (action potential)
• Glial cells: provide support (do not transmit nerve impulses)

Front 26

Neuron 3 basic components

Back 26

• cell body: contains organelles
• dendrites: receive signals and conduct them to cell body
• axon: generates and conducts action potentials

Front 27

Neuron types

Back 27

• Multipolar → large number of dendrites and one axon (most common)
• Bipolar → one dendrite and one axon (retina, cochlea)
• Unipolar → single process from cell body → splits into dendrite & axon (somato-sensory)

Front 28

Glia-4 types

Back 28

• → different supportive mechanisms (No action potential)
• Oligodendrocytes → forms myelin sheath in CNS
• Astrocytes → several functions- blood-brain barrier, ionic balance, nutrition
• Microglia → derived from monocyte - macrophage (phagocytic)
• Ependymal → line the ventricles → produce CSF/ maintain CSF-brain barrier

Front 29

Synaptic transmissions?

Back 29

• most nerve/muscle connections are by way of neurotransmitter release into synaptic cleft by “pre-synaptic” neuron → across cleft and binds to “post-synaptic” receptor to excite, inhibit or modify activity
-based on the type of ion channel opened/closed

Front 30

6 Neurotransmitters

Back 30

• Acetylcholine- autonomic ganglia, post-ganglionic p-symp and neuromuscular jxns
o degraded by acetylcholinesterase→ limits duration of effect/also negative feedback
• Amines- dopamine, nor-epinephrine, epinephrine, serotonin, histamine
o limbic system, basal ganglia, SNS post-ganglionic
o degraded by monoamine oxidase (enzyme)
• Amino acids- excitable and inhibitory
o glutamate and aspartate→excitable
o Glycine and GABA→inhibitory
• Neuropeptides- released with other neurotransmitter → may prolong/change effect
o endorphins, substance P, enkephalins
• Purines- ATP and adenosine - may modulate neurotransmitter release
• Nitrous oxide- diffuses into cell → affects cGMP levels, change ion pumps/ enzymes

Front 31

Generally, neurons that are injuried do not____
Peripheral nerves have potential to____
Also, neural stem cells in ventricles/hippocampus can____

Back 31

• Generally, neurons that are severely injured do not regenerate.
• Peripheral nerves have potential to re-grow if Schwann cells provide pathway
• Also, neural stem cells in ventricles/hippocampus can proliferate (further research)

Front 32

Head Trauma--->

Ischemia/Hypoxia →

Back 32

Head trauma → neuronal damage (primary) → edema→ further damage (secondary)

Ischemia/Hypoxia → oxygen delivery lower than metabolic demands
• Neural tissue has high metabolic O2 demands → sensitive to low O2 (poorly anaerobic)
• Most of the ATP requirement is for maintenance of ion gradients across pl. membrane.
• Cerebral blood flow auto-regulated based on pH, CO2 and O2 levels → may develop poor auto-regulation during periods of extremely high/low blood or ICP pressures.

Front 33

Increased Intracranial Pressure

Back 33

• May occur w/ most types of acute brain injury
o CVA, trauma, tumors, hemorrhage
• skull rigid: closed and pressure not able to be relieved or reduced
• 3 components (blood/CSF/ brain tissue) → increase in one may be offset (to a point) by a decrease in another → if not, brain tissue swells/damaged and herniates downward → cardio-respiratory depression/pupils dilate

Front 34

Evaluation of head injuries

Back 34

• Level of Consciousness
• Glasgow Coma Score (Eyes 4/ Speech 5/ Motor 6)
• Cranial Nerve Reflexes (pupils, corneal, oculovestibular)

Front 35

Intracranial Hematomas 3

Back 35

• Epidural- blood in epidural space, lucid interval, assoc. fractures, concave dura
• Subdural- between dura and arachnoid, bridging veins, dura against skull
o chronic vs. acute
o may have subtle Sxs (and go undiagnosed)
• Subarachnoid- rupture of aneurysm, AVM, trauma- blood in CSF
o nuchal rigidity

Front 36

Ishemic Stroke--->
pre-numbra?
TIA
Hemorrhagic Stroke
May cause

Back 36

• Ischemic Stroke → Thrombotic (atherosclerosis) vs. Embolic (cardiac orgin)
o “pre-numbra”- cells surrounding ischemic area but still viable.
• Transient Ischemic Attack (TIA) → high recurrence (should be evaluated for source)
• Hemorrhagic Stroke → usually secondary to severe and long standing HTN
o 38% mortality
• Most commonly in basal ganglia or thalamus
• May cause increased ICP

Front 37

AHA Guidelines

Back 37

AHA Guidelines for Thrombolytic Therapy
• 3 hours since onset
• Measurable neuralgic deficient
• 18 years or older

Front 38

CNS Infections

Back 38

• Meningitis (bacterial, viral, fungal, parasitic)
• Encephalitis(same as meningitis but viral most common)
• Brain abscess

Front 39

Seizure Disorders
Epileptogenic focus:

Seizure threshold

Back 39

Seizure: paroxysmal transient event with excessive/abnormal cortical electrical discharges resulting in disturbances in skeletal motor function, sensation, visceral function, behavior or consciousness.
Epileptogenic focus: area of brain with neurons abnormally hyperactive secondary to altered membrane potential.
• Generalized vs. Partial
• Aura/prodrome

• Seizure threshold may be lowered with head injury, electrolyte imbalances, sleep loss, toxin/drug exposure, acidosis, fever, etc.

Front 40

Parkinson's Disease
___vs____
causes
what is it___
SxS

Back 40

• Idiopathic vs. Acquired.
• Infection, toxins, trauma, etc.
• Degeneration of pigmented dopaminergic neurons - substantia nigra
• Slow to diagnose - vague early Sxs
o Rigidity, fatigue, tremor, bradykinesia, hypokinesia
o Loss of facial expression, decreased blinking, stammering/mumbling

Front 41

hydrocephalus

Back 41

abnormal amount of CSF- normal pressure/obstructive/communication

Front 42

MS
what is it?
most in who?
sxs
where is it?

Back 42

chronic demyelinating of the CNS
• young adults - disabling
• ? auto-immune→ inflammation/scarring (sclerosis)-variable progression
• Lesions anywhere in the CNS→ variable Sxs
o Vision, movement, sensory, coordination, mood/behavior, sexual dysfunction, cognition
• No conclusive test→ clinical characteristics and labs
o MR may indicate presence but poorly related to clinical findings/prognosis.

Front 43

GB

Back 43

• “idiopathic polyneuropathy” → inflammatory demyelination of peripheral nerves (toes and fingers first)ascending
• Male = Female incidence
• ? etiology: frequently follows infection (Campylobacter jejuni), immunization or surgery
• Progressive ascending weakness or paralysis - may affect respiratory muscles
• Loss of DTRs
• Peak disability @ 10-14 days typically
• Most patients have spontaneous recovery

Front 44

Bell's Palsy

Back 44

• Acute, idiopathic paresis/paralysis of the facial nerve VII←infl. @ stylomastoid foramen
• Probably related to viral infection (Herpes simplex/zoster)
• Unilateral facial paresis (upper and lower face)
o diminished blink, hyperacusis (senetive ear, posterior auricular pain, decreased lacrimation.
•Rx: tape eye, moisture, ? anti-virals and steroids

Front 45

Middle Ear
Inner Ear

Back 45

Middle Ear
-ossicles, amplification, Eustachian tube
Inner Ear
-coclea, semicircular canals, perilymph, organ of Corti, VIII nerve

Front 46

Conductive Hearing Loss

Back 46

• obstruction (cerumen)
• mass loading (effusion)
• stiffness effect (otosclerosis)
• discontinuity (ossicular disruption)

Front 47

Sensorineural hearing loss

Back 47

• Inner ear, cochlea → VIII nerve or brain
• Ototoxic drugs, loud sounds, trauma, metabolic
• Meniere Disease-excessive endolymph→tinnitus, S/N hearing loss, vertigo, ear fullness

Front 48

Visual field sides of vision

Back 48

• Review of visual fields → nasal retina sees lateral/ temporal retina sees medial

Front 49

Smell disorders usually due to?

Back 49

URIs, smoking, allergies, (? brain tumor)