Motor pathways Flashcards
where is cell body and synape of UMN
body in cortex, synapse on LMN
where is body and synapse of LMN
body in brainstem or cord, synapse on striated muscle
where are LMN bodies and nerve in brainstem
body in cranial nerve nuclei, travels in cranial nerve
where are LMN bodies and nerve in cord
body in ventral horn, travel via ventral root>spinal nerve>peripheral nerve
what is only nerve to touch the muscle
LMN – final common pathway
where is motor column in brainstem and cord
brainstem - series of motor nuclei
cord - in ventral horn
what do medial portions of motor column innervate
ipsilateral axial muscles for posture and balance
what do lateral portions of motor column innervate
(only in cervical and lumbar) - ipsilateral limb muscles for skilled voluntary movement
what is stretch reflex
stretch causes contraction to maintain muscle length
what are 4 levels that can be tested and where
C6 - boceps
C7 - triceps
L4 - patellar
S1 - achilles
what happen to reflex in LMN lesion
abolished
what happens to reflex in UMN lesion
enhanced via lack of inhibition
5 signs of LMN lesions
- ipsilateral weakness
- hyporeflexia
- flaccid paralysis (lower tone)
- atrophy - loss of trophic substances
- fasiculations - tiwitching in early onset
what are 4 interneuron UMN tracts and what do they control
- vestubulospinal - balance equilibrium
- reticulospinal - posture and gait
- rubrospinal - limb flexors
- corticospinal - skilled voluntary movement
what is lateral corticospinal tract (LCST)
UMNs that allows skilled asymmetic movement
where are bodies of LCST
in motor cortex
where to LCST fiber decussate
at junction of medulla and cord
where to LCST fibers synapse
on LMN in the cervical and lumbosacral enlargments
what is axonal path of CST neurons
corona radiata>internal capsule>cerebral peduncles>pyramids>LCST
what is babinski sign
normal stroking causes plantarflexion, but in UMN lesions causes dorsiflexion
what happens in lesion of LMN in cord
ipsilateral effects
what happens in lesion of CN nucleus or CN with LMN in it
ipsilateral effects except for trochlear, which is contralteral for nucleus and ipsi for nerve
what is corticobulbar tract
extends from cortex to the bulb, or brainstem
which CNs are innervated by tract and which are not
are: V, VII, IX, X, XI, XII
not: III, IV, VI
