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anterior horn of grey matter
contains alpha motor neurons and motor fibers innervating skeletal muscles
path of corticospinal tract
descends from the cortex and crosses midline in the medulla, then synapses on alpha motor neurons in anterior horm. Runs laterally in cord.
path of dorsal columns
ipsilateral to origin, then crosses in brainstem
path of anterolateral spinothalamic tracts
begins in peripheral nerves (pain and temp), enters cord and synapses within 2 levels, then crosses and ascends contralaterally
which spinal nerve contains no sensory fibers
spinal cord ends at
transection above C3-C5...
abdominal reflexes lost with lesions...
weakness and hyperreflexia ipsilateral to and below the lesion (corticospinal tract), impaired position sense below the lesion, loss of pain and temp perception below level of lesion but contralateral to lesion
lesioins in central spinal cord
affects spinothalamic tract fibers crossing at level of lesion
deficits in pain and temp sensation bilaterally over several segments (cape-like). pain and temp affected byt NOT touch or position
ex: syringomyelia - expansion of potential fluid space in center of spinal cord. May be associated with posterior skull and brain malformations such as Chiari malformations
posterior columns (tabes dorsalis). B12 targets posterior columns also
Cauda equina lesions
wasing, weakness, and fasciculations in appropriately innervated muscles lumbrosacral region with pain. Sacral root dysfunction can cause bowel, bladder, and sexual dysfunction
conus medullaris lesions
upper motor neuron findings, radicular pain, bowel, bladder, and sexual dusfunction. If lesions are below the lumbar cord, may leave leg strength and reflexes intact while severely affecting bowel, bladder, and sexual function
blood supply to the anterior 2/3 of cord
anterior spinal artery
caudal arterial supply to anterior spinal artery
artery of adamkiewicz, entering the spinal cnal around L2
dorsal columns supplied arterieally by
plexus fed by segmental arteries from the aorta
anterior spinal artery syndrome
weakness below lesion, intense radicular pain, sphincter dysfunction, sensory loss but not position loss, thoracic cord is lease well perfused and most vulnerable. Systemic hypotension can lead ot watershed infarct affecting this area.
to treat traumatic spinal cord compression
high doses of steroids
due to mutation in the superoxide dismutase enzyme, leading to exitotoxin damage
involve alpha motor neurons (lower motor) of anterior horm of spinal cord, leading weakness, faciculations, and wasting. Also involves lateral corticospinal tracts leading to weakness, spasticity, hyperreflexia, and Babinski signs
No sensory deficits, eye movements unaffected.
Tx: riluzole slows deterioration.
Things that mimic ALS: stenosis of spinal canal (EMG testing), hereditary spastic paraparesis (HTLV-1 testing), severe nutritional deficiency.
Things that affect alpha motor neurons but w/o spasticity or sensory deficits - spinal muscular atrophies
SMA presenting in infancy - atrophy of anterior horn cells
downward protursion of the medulla, with or without cerebellum, through the foramen magnum
Tethered cord syndrome
hypertrophy of the filum terminale - pain and dysfunction of cord, especially at lower levels