Motor Neurons 2 - Kenyon Flashcards
cell bodies located lateraly project to muscles of posture or skilled movement?
skilled movement
cell bodies located medially in the spinal cord project to postural or muscles of skilled movement?
postural muscles
In the lateral CST, where are the lower motor neurons located?
In the lateral ventral horn
In the ventral CST, where are the lower motor neurons located?
in teh medial ventral horn
Does the ventral CST decussate?
No
Where are the upper motor neurons originating for the vestibulospinal and reticulospinal tracts?
brainstem
dot the vestibulospinal and reticulospinal tracts decussate?
NO
Is there extensive crossing over of the medial local circuit neurons controlling posture?
yes
Do the local circuit neurons controlling posture control muscles independently or groups of muscles?
groups of muscles
Is there extensive crossing over of the local circuit neurons controlling skilled movement?
no
Do the local circuit neurons controlling skilled movement control muscles independently or groups of muscles?
independent muscles
The lower motor neurons controlling muscles of the face are in the (blank). They receive input from upper motor neurons via (blank) tract
brainstem
corticobulbar
Lower motor neurons controlling the muscles of the body are in the (blank) They receive input from upper motor neurons via the (blank) tract
spinal cord
corticospinal
Can upper motor neurons contribute to both the corticobulbar and corticospinal tracts?
yes
the corticobulbar tract would find its upper motor neurons medial or lateral on the brain somatotopy?
lateral
the corticospinal tract would find its upper motor neurons medially or laterally on the brain somatotopy?
medial`
At what level does the corticospinal decussate? what is the name of the decussation?
Caudal medulla; pyramidal decussation
On the shared CST and corticobulbar tract, where do the corticobulbar fibers head off to in the middle medulla?
to the reticular formation
In what nuclei does the CST synapse in the dorsal column?
Gracile and cuneate
What body structures does the lateral CST control?
limbs and hands
what body structures does the ventral CST control?
hip, trunk, shoulder, elbow, and neck
Can neurons from the ventral CST send fibers to the reticular formation?
Yes
Why is is that the neurons in the motor and premotor cortex branch to synapse in both the lateral and ventral CST?
to coordinate postural adjustments
Lower motor neurons controlling superior and inferior facial muscles are located in the (ipsilateral/contralateral) facial nerve (VII) nucleus.
ispilateral
Upper motor neurons originate in (contralaterally/ipsilaterally) that control lower motor neurons controlling inferior facial muscles
contralaterally
Upper motor neurons originating in the contralateral and ipsilateral (blank) gyrus project (cortico- bulbar) to lower motor neurons controlling superior facial muscles.
cingulate
Primary and premotor complex controls upper or lower face muscles?
lower
Cingulate gyrus controls upper or lower face muscles?
upper
Lesions in the right primary motor cortex will have what effects on facial expression? is this upper or lower motor neuron lesion?
Loss of LOWER muscles to LEFT face; UPPER lesion
Lesions in the tract common to both the pimary cortex and cingulate gyrus will have what effects on facial expression? Why is it this way?
Upper motor neuron lesion; loss of CONTRALATERAL LOWER face. Upper face maintained by bilateral input from cingulate gyrus
Lesions below the last synapse of either facial tract will lead to what change in facial expression
full loss on CONTRALATERAL side, both top and bottom
Occlusion of the middle cerebral artery will result in what facial deficits?
Weakness/paralysis in inferior facial muscles
Ispilateral neurons of the (blank) gyrus maintain superior facial expression despite anterior cerebral artery occlusion
cingulate
What are the three major upper motor neuron nuclei of the brainstem?
Vestibular, reticular formation, and superior colliculus
What is the main input to the vestibular nuclei?
semicircular canals
What is the output for the vestibular nucleus?
vestibulospinal tract
where does the vestibulospinal tract go in the cord?
medial (and some lateral) regions, but mostly medial
What is the function of the vestibulospinal tract?
posture and VOR
what are the primary inputs from the reticular formation?
pimrary motor cortex via ventral CST and corticobulbar
what is the primary output tract of the reticular formation?
reticulospinal
where does the reticulospinal tract go?
medial spinal cord
What is the function of the reticulospinal tract?
posture
what are the primary inputs to the superior colliculus?
upper body proprioceptors, retina, auditory, olfaction, corticolbular form FEF
where do the fibers from the superior colliculus go?
motor nuerons innervate neural ciricuts in the reticular formation that give rise to reticulospinal projections
What is the function of the fibers leaving the superior colliculus?
axial muscles in the neck that oritentate the head, SACCADES
What is considered the indirect action of upper motor neurons?
postrual adjustment following instability
Direct pathways between UMN and LMNs go straight through the cord while indirect pathways synapse in the (blank)
brainstem (sup colliculus and reticular formation)
What is the function of the lateral premotor cortex
sets the intent to make a movements, selects appropriate movements, and responds to external cues
what is the function of the medial premotor cortex?
same as the lateral premotor cortex but for internally generated movements (because I want to vs my life is in danger)
In an UMN syndrome, is the brainstem and spinal cord intact?
yes
do local circuit neurons still recieve sensory input in UMN syndrome?
yes
What is spinal shock of UMN syndrome?
contralateral flaccidity
LOSS of reflexes, but only while the shock is present
What are the long lasting responses of UMN syndrome?
Babinski sign Spasticity HYERREFLEXIA weak superficial reflexes (cornea, cremasteric) loss of fine movements clonus
What are the symptoms of LMN syndrome?
Weakness/paralysis DECREASED superficial and deep reflexes decreased tone FASCICULATIONS and fibrillations MUSCLE ATROPHY
