Motor Systems (Lecture #7) Flashcards
what is the only pathway we possess to move our extremities voluntarily
lateral corticospinal tract
what does the lateral corticospinal tract pathway do
voluntary movement of extremities
voluntary unilateral movement of trunk
(nothing with head or neck)
how many neurons does the lateral corticospinal tract consist of?
2
upper motor neuron and lower motor neuron
where is the cell body of the upper motor neuron of the corticospinal tract?
primary motor cortex
where is the cell body of the lower motor neuron of the corticospinal tract?
ventral horn of the spinal cord
Pathway of axon of the upper motor neuron of the corticospinal tract
corona radiata internal capsule (posterior limb) basis of midbrain basis of pons basis of medulla crosses midline at pyramidal decussation (caudal medulla) lateral aspect of spinal cord
where does the axon of the lower motor neuron of the corticospinal tract travel?
travels out ventral horn via ventral root spinal nerve plexus peripheral nerve synapses with muscle
corona radiata
axons heading to or from the cerebral cortex superior fo the thalamus
area IX of the spinal cord
location of lower motor neuron
occupies medial and lateral portion of each ventral horn
LMN for UE and LE are in lateral portion of area IX
what parts of the spinal cord is the lateral part of area IX the largest
cervical
lumbosacral
what part of the cervical enlargement provides axons for proximal part of UE
rostral part
C5-6
what part of the cervical enlargement provides axons for the distal part of UE
caudal part
C8-T1
what part of the lumbosacral enlargement provides axons for the proximal part of LE
rostral part
L2-4
what part of the lumbosacral enlargement provides axons for the distal part of LE
caudal part
L5-S2
Where does the cell body of the LMN always come from for muscles of the right side of the body
right ventral horn
L ventral horn –> muscles on L side
function of anterior corticospinal tract
voluntary control of proximal extremities and trunk muscles
-especially when you move both sides simultaneously
decussate
cross midline
if pt damages left motor cortex, will he/she still be able to move his/her right trunk/proximal extremities
yes, but only bilaterally simultaneously
where does UMN of lateral corticospinal tract decussate
caudal medulla
where does UMN of anterior corticospinal tract bifurcate?
at spinal level of LMN in spinal cord
where does axon of anterior corticospinal tract travel in spinal cord
anterior (ventral) column
where does axon of lateral corticospinal tract travel in spinal cord
lateral column
function of corticobulbar tract
voluntary movements of head and neck
which CNs motor nuclei are on the midbrain
III
IV
which CNs motor nuclei are on the pons
V
VI (eye mvmt)
VII (rostral/caudal halves = upper/lower face)
which CNs motor nuclei are on the medulla
IX (swallowing)
X (vocalization)
XII (tongue)
which CNs motor nuclei are on the spinal cord
XI (shoulders, turn head)
do the UMNs for the upper part of the face bifurcate?
yes
do teh UMNs for the lower part of the face bifurcate?
no, they cross the midline and innervate contralaterally
what is the most notable clinical sign when a person has damage to UMN in lateral corticobulbar tract supplying the lower part of face
paralysis of lower part of face on opposite side
