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What does the CNS develope from?

What does the PNS develope from?
-neural tube

-neural crest
When does neural tube formation begin and then close?

What does the neural crest, located between the neural tube and skin ectoderm, differentiate into?
-between day 18 and 26 of gestation

-dorsal roots, spinal nerves, cranial nerves, adrenal medulla, ANS ganglia, and meninges
What does folic acid supplementation prevent in utero?

400 mcg per day can prevent what deformity?
-risks of neural tube defects

-spina bifida
What are the clusters of grey matter deep inside the brain (grey matter is generally surrounding the hemispheres)?

What is the difference between grey and white matter?

-grey is neuronal cell bodies
-white is myelinated axons
What are the four regions of the brain?

What are the cerebral hemispheres?

State which is motor and which is sensory:

-anterior cerebrum
-posterior cerebrum
-motor (doing)

-sensory (sensing)
What are the major functions of the frontal lobe?
-problem solving
-primary motor region on the precentral gyrus
WHat are the major functions of the temporal lobe?

The parietal lobe?
-short-term memory

-primary sensory region
WHat do lesions on the primary sensory region of the parietal lobe cause?

What are the major functions of the occipital lobe?
-sensory deficits of astereogenosis
-hemisphere neglect
-inability to copy figures

-visual processing
-hape and color identification
What is the only portion of the brain that connects the hemispheres?

What is the basal ganglia associated with?
-corpus callosum

-learning and movements
What is the mahor sensory relay in the brain?

What is the function of the hypothalamus?

-master and commander of ANS
-maintains homeostasis
What is responsible for the sleep wake cycle?

What are some characteristics of the cerebellum?

-10% of brain vol.
-50% of neurons in CNS
-2 hemis
-10 indiv. lobes
What is the blood supply to the cerebellum?

What are the major functions of the cerebellum?
-AKA: posterior circulation

-sensory perception
-motor control
What do lesions on th cerebellum cause?

What is ataxia?
-no paralysis
-feedback disorders: equilibrium, posture, and motor learning

-a wide based, wobbly gait caused by a localizing cond.
What are the three parts of the brainstem?

What primarily arises from the brainstem, nerve wise?

-cranial nerves
What tracts move through the midbrain?

And what do they do?
-pyramidal: voluntary movement

-extrapyramidal: involuntary movements (posture, adjustments, coordination)
What structures coordinate consciousness?

What is the function of the RAS?
-cerebral hemis

-responsible for conscious state
What does na insult to the RAS result in?

Where should all midlines be?

If you suspect a stroke or subarachnoid hemorrhage, what test should you get immediately?

WHat about a tumor?
-non-contrast CT ASAP

-CT with and without contrast
What are some causes for the inability to use a CT?

What is the #1 risk factor for an intercerebral hemorrhage?
-inability to lie flat or lie still
-dye allergies or kidney disease

Where does the spinal cord originate and extend to?

Where does the cauda equana begin?
-medulla to the 1st or 2nd lumbar vert.

-at L1-L2
What are deep tendon reflexes/muscle stretch reflexes?

What spinal nerves are tested by stroking the abdomen toward the umbilicus above and below?
-an involuntary stereotypical response tha tinvolves structures of the PNS and CNS, sensory and motor fibers

Name the spinal nerve for the given structures during a spinal reflex:
-ankle: S1
-knee: L2/3/4
-brachioradialis: C5/6
-biceps: C5/6
-triceps: C6/7
What spinal nerves are affected by the plantar reflex?

What are the 3 responses possible from the plantar reflex?
-L5, S1

-normal: toes go downward (plantar flexion)
-abnormal: toes go upward (dorsiflexion)
-babinski response: dorsiflextion of the big toe with fanning of the other toes
What is the gradign scale for the reflexes?

Defne clonus?
3+=hyperactive without clonus
4+=hyperactive with clonus

Clonus: alternate involuntary muscular contraction and relaxation in rapid succession
Should reflexes be symetric or asymetric?

What are the 3 spinal tracts and their associated function?

-corticospinal: voluntary motor activity
-spinathalamic: pain and temp.
-dorsal columns: light touch/vibration/position sense
Where does the corticospinal tract cross in the spinal column?

Where does it end?
-the medulla

-anterior horns of the spinal column
Where do the dorsal column fibers cross the midline?

Where do the spinothalamic tract fibers cross the midline?
-the medulla

-immediately when they enter the spinal cord
Which of the tracts will be contralateral in presentation with a lesion to the spinal cord?

Where does the arterial blood supply to the brain come from?

-the bilateral internal carotid and bilateral vert. arteries
What is the flow of blood from the brain (venous)?

-blood goes into the dural sinuses, exits within the dura

-passively flow into the jugular vein

-direct communication with venous drainage of the face
What is an epidural hematoma?

How dies it appear on a CT?
-blood between the inner surface of the skull and the dura caused by aterial blood generally from damage to the middle meningeal artery which lies in the tempal

-Consolidated ball against the skull
What is a subarachnoid hemorrhage?

What is indicative of this hemorrhage on a CT?
-blood the is pulling below the arachnoid

-the blood will be seen following the sulci
WHere is CSF secreted and absorbed at?

What is hydrocephalus?
-secreted from the choroid plexus
-absorbed in th esubarachnoid space

-an accumulation of CSF within the ventricles
Where do sympathetic fibers exit the spinal cord in the ANS?

Where do parasympathetic fibers exit the spinal cord in the ANS?

-CN III, VII, IX, X, and S2-S4
WHat privdes master control over the ANS?

-the hypothalamus
How many pairs of cranial nerves and spinal nerves are there?

What are the purely sensory nerves again?
-12 cranial and 31 spinal

-I, II, and VIII
What are the purely motor?


-V, VII, IX, X
What is the blood supply called for nerve bundles?

What myelinates nerves in the PNS and CNS?
-vaso nervorum

-PNS: schwann cells
-CNS: oligodendrocytes
What enhances nerve conduction velocity?

Where are voltage gated channels only located in a myelinated axon?
-nerve diameter and myelination

-nodes of ranvier
What is the process for a synapse?
-nerve impulses arrives causing an influx of Ca+

-Ca+ causes the release of neurotransmitters

-they diffues across synapse

-bind to membrane receptor proteins

-neurotransmitter is broken down
When does summation occur?

What two reactions can a neurotransmitter cause?
-when multiple stimuli are added together to produce an action potential

-excititory and inhibitory
What are the three various locations for synapses on a neuraon?

What occurs during depolarization and hyperpolarization?

-depolarization is caused by open sodium gates
-hyperpolarization is caused by open potasssium gates
What is polyneuropathy?

What nerves are generally more susceptable to this disorder?
-a typically distal, symetric loss of sensory and weakness

-typically length dependent, thus the longest axons are the most vulnberable
Where is polyneuropathy generally distributed too?

What is an isolated peripheral neuropathy of the face?

-bells palsy
What is an isolated peripheral neuropathy of the radial portion of the forearm?

-"saturday night palsy"

-carpal tunnel
What is an isolated peripheral neuropathy of the ulnar?

What is an isolated peripheral neuropathy of the lateral femoral cutaneous nerve?
-"funny bone" tingling

-meralgia paesthetica
What is an isolated peripheral neuropathy of the peroneal nerve?

What is an isolated peripheral neuropathy of the posterial tibial nerve?
-common mononeuropathy in lower limbs

-tarsal tunnel syndrome
What is carpal tunnel syndrome?

What are some symptoms?
-median nerve entrapment

-intermittent nocturnal paresthesias of the thumb, index, and middle fingers (M)
-will often awaken from sleep
-often relieved by shaking
What are some exam findings indicative of carpal tunnel syndrome?
-decrease in pin or light touch sensation in the palmar aspect of affected fingers

-weakness and atrophy of the thenar eminance

-pain - predominant symptom

-dominant hand more susceptable

-middle-aged women
What are CTS frequently caused by?

WHat are some treatments for mild CTS?

-w/o sensory or motor weakness: nocturnal wrist splint, avoiding offending posture, and oral or injected steroids
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