Descending Motor Pathways Flashcards
descending motor pathways
corticospinal tract- cortex to spinal cord
corticobulbar tract- cortex to brainstem
corticopontine tract- cortex to basilar pons
corticospinal tract made up of fibers from:
primary motor area (precentral gyrus)
somatic sensory area (postcentral gyrus)
premotor area; lateral surface of cerebrum
supplementary motor area; medial surface of cerebrum
superior parietal lobule
function of the primary motor area
- execution of contralateral voluntary movements
- control of fine digital movements
lesion to primary motor area results in:
paralysis of contralateral muscles
primary motor area projects to the ____ and ____ with some monosynaptic terminations on spinal cord motor neurons in the ____
brainstem; spinal cord; hand
function of premotor area
- plans movements in response to external cues
- control of proximal and axial musculature
- may assemble empathetic facial movements
premotor area projects to ____ and _____; some fibers project to all spinal cord levels
primary motor area; reticular formation
lesion to premotor area results in:
- moderate weakness of contralateral proximal muscles
- loss of ability to associate learned hand movements to verbal or visual cues
supplementary motor area function:
- plans movements while thinking (internally paced)
- assembles or learns new sequence
- assembles previously learned sequence
- “imagines” movements
supplementary motor area projects to ____ and _____
premotor; primary motor areas
____ and ____ project to primary motor area to direct motor patterns in response to sensory input; also project to areas of ____ and _____ to modulate sensory signals
somatic sensory area (postcentral gyrus); superior parietal lobule; brainstem; spinal cord
CST has collateral projections to:
basal ganglia, thalamus, reticular formation, various sensory nuclei (dorsal column nuclei), posterior and intermediate horns of the spinal cord
____ and ____ are perforating arteries off the middle cerebral a. that supply the basal ganglia
lateral striate aa. ; anterior choroidal a.
corticospinal fibers descend in the ____ third of the cerebral peduncle
middle
rubrospinal tract function
control of shoulder and proximal arm musculature
reticulospinal tract function
control of axial musculature- walking
vestibulospinal tract function
control of axial musculature- balance
tectospinal tract function
believed to be important in head turning reflexes in response to visual stimuli ; unclear function in humans
origin of vestibulospinal tract
vestibular nuclei in the pons
vestibulospinal tract receives input from:
vestibular system and cerebellum (balance)
the lateral vestibulospinal tract projects via lateral funiculus to ____ and facilitates _____
ipsilateral spinal cord; antigravity muscles
medial vestibulospinal tract projects via anterior funiculus to ____ spinal cord levels bilaterally and controls ____ movements in response to gravity
cervical; head
function of vestibulospinal tract:
- mediates postural adjustments and head movements
- antigravity reflexes
- righting reflex in cats
lower motor neuron lesion results in:
- atonia
- areflexia
- flaccid paralysis
- fasciculations
- atrophy
UMN lesions result in:
- spastic paralysis (paresis)
- hypertonia (increased resting tension)
- pathologic reflexes (i.e. Babinski sign, negative plantar reflex)
- milk disuse atrophy
in the corticobulbar tract, CNs ______ receive bilateral input
V, VII, nucleus ambiguus (part of X), XI, and XII
corticobulbar pathway originates in ____ portion of motor cortex and other nearby areas
face/mouth
