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Which has the ability to regenerate? CNS or PNS
PNS, nerves regrow at 3mm/day
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Astrocytes
The supporting glial cell of the CNS both structurally and metabolically; contains GFAP marker useful in identifying tumors
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Microglia
phagocytic cells of the CNS
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Oligodendrocytes
myelin-forming cells of the CNS; 1 cell can myelinate up to 30 axons
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Schwann cells
myelinating cells of the PNS; 1 Schwann cell produces 1 internode
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Ependymal cells
line central canal and ventricles; produce CSF
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Neurofibromatosis, type 1
- Neurofibromas
- Gliomas of optic nerve, pigmented lesions of iris (Lisch nodules) and cafe‐au‐lait spots
- NF1 gene at 17q11.2 – neurofibromin – tumor suppressor gene
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Neurofibromatosis, type 2
- Bilateral schwannomas and multiple meningiomas may occur
- Gliomas (ependymomas of spinal cord)
- NF2 gene at 22q12 ‐ merlin
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Tuberous Sclerosis
- Hamartomas of brain – cortical tubers and subependymal hamartomas (candleguttering)
- Organ cysts, angiofibromas, shagreen and ash‐leaf (skin) patches, and subungual fibromas.
- Genes – TSC1 at 9q34 – hamartia; TSC2 at 16p13.3 – tuber in
- Subependymal giant cell astrocytomas can occur
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Von Hippel‐Lindau
- Hemangioblastoma – cerebellum, retina, brain, spinal cord)
- Pancreas, liver, kidney cysts
- Renal cell carcinoma
- Gene on chromosome 3p25‐26 coding pVHL
- Hemangioblastoma cells produce erythropoietin – polycythemia
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Sturge‐Weber
- Venous angiomatous masses in leptomeninges
- Ipsilateral port‐wine stain of face
- Mental retardation, seizures, hemiplegia, radiopacities in skull
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Which tract carries parasympathetics to S2-S4? What happens when this tract is severed?
Corticospinal tract to the sacral nerves; loss of voluntary bladder and bowel control.
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Which spinal tracts are affected in with vitamin B12 neuropathy (aka: subacute combined degeneration)?
Dorsal columns, lateral corticospinal tracts, spinocerebellar tracts (arm/leg dystaxia)
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Guillain-Barre syndrome: which nerves are affected?
motor fibers of ventral roots and peripheral nerves producing LMN symptoms (m weakness, ascending flaccid paralysis, areflexia)
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Guillain-Barre syndrome: Features
- Demyelination and edema
- Upper cervical root (C4) involvement and respiratory paralysis
- Facial diplegia (CN involv)
- Elevated protein (causing papilledema)
- Lesser degree: paresthesias
- Increased CSF protein w/o pleocytosis (albuminocytologic dissociation)
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where does spinal cord end on infants and adults?
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Disk herniation between L4 and L5: which spinal nerve will be affected?
L5; the spinal nerves T1-S4 come out below their corresponding vertebrae; the lumbar nerves cross over the junction above the corresponding vertebrae
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Disk herniation between C5 and C6: which nerve is affected?
C6; the spinal nerves C1-C7 emerge above their corresponding vertebrae but unlike T and L spinal herniations, Cervical herniations affect the nerve emerging at that junction
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Conus medullaris syndrome (S3-coccygeal)
Results in bilateral pain, normal reflexes, incontinence and sexual functions impaired, onset sudden and bilateral
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Cauda Equina syndrome (L3-Coccygeal)
unilateral pain, unilateral muscle atrophy and absent lower reflexes (S1 and L3)
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Explain corticobulbar innervation of facial nerve nucleus
- Facial nerve nucleus that innervates the upper face receives bilateral corticobulbar input
- Facial nerve nucleus that innervates the lower face receives only contralateral corticobulbar input
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With trigeminal sensation, which is contralateral vs. ipsislateral: pain and temp (ventral) vs. discrimination and pressure (dorsal)?
- pain and temp: contralateral, 2nd order fibers decussate in lower medulla
- discr. and pressure: ipsilateral, 2nd order nuclei are in the principal sensory nucleus of V
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What is the drug of choice for Tic douloureux?
Carbamazepine
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Functions of CN VII
- Facial movements
- taste (ant 2/3)
- salivation
- lacrimation
- general sensation from external ear
- Stapedius m (hyperacusis if paralyzed)
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Crocodile tears
lacrimation during eating as a result of aberrant regeneration after trauma
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3 Things required for balance
- cerebellum
- sight
- vestibular system
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Functions of CN IX
- Taste and general sensation (post 2/3)
- Salivation (parotid)
- Swallowing (stylopharyngeus)
- Input from carotid sinus and body
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Functions of CN XI
- Cranial division-n.ambiguus-intrinsic mm of the larynx via inferior (recurrent laryngeal nerve) except cricothyroid m.(CNX)
- Spinal division-from C1-C6-sternocleidomastoid and trapezius
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Stylopharyngeus
Cricothyroid
Inferior (Recurrent) laryngeal nerve->intrinsic larynx mm
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