4-Corticospinal Tract Flashcards
splits into what tracts
@ caudal medulla
- anterior corticospinal for cervical and upper thoracic levels
- lateral corticospinal for all spinal levels
pathway
- layer V of cortex/pyramidal
- corona radiata
- internal capsule (genu then posterior half of post limb)
- basis pedunculi of midbrain
- basal pons
- pyramid of medulla to decussate
- LMNs @ ventral horn
anterior CST functions in what
controlling axial muscles (neck, shoulder, upper trunk)
lateral CST functions in what
execution of distinct, skilled, well defined vol move of opposite side of body esp hand AND controls muscles of lower limb
lesion above decussation =
deficits contralateral to side of lesion
lesion below decussation =
deficits ipsilateral to side of lesion
UMN lesion signs
spastic paralysis
- initial/temporary muscle weakness (paresis) + flaccid paralysis + hypotonia + hyporeflexia
- regain function of proximal limb muscles, crude moves, fine moves of hand affected most
- shift to abnormal inc muscle tone (hypertonic) + severe hypertonicity/spasticity in distal limb muscles
why hypertonia in UMN lesion
UMN lesion damages more motor tracts than CST so descending inhibitory influences are eliminated
=overactive gamma motor neurons and hypertonia
extensor plantar response
babinski
if lesion of lateral CST then stroking plantar surface of foot = dorsiflexion of big toe + fanning of others
normal response is to plantar flex all 5
other UMN lesion signs
due to trauma or stroke
- hyperreflexia from overactive gamma motor neurons
- mild muscle atrophy
- babinski’s sign
LMN lesion signs
aka damage to neuron cell bodies or motor nerve to muscle
1. dec muscle strength
2. hypotonia
3. hyporeflexia or areflexia
4. flaccid paralysis
5. severe muscle atrophy
6. fibrillations/invol contractions
7. fasciculations/twitching
anterior cerebral A occlusion =
lesion in medial surface of M-I cortex
=motor deficits in contralatral leg and foot
middle cerebral A occlusion =
lesion in lateral surface of M-I cortex
=motor deficits in contralateral UL and face
lenticulostriate a occlusion =
motor deficits in contralateral side body
posterior cerebral A occlusion =
lesion in midbrain basis pedunculi
=motor def contralateral body