Cortical Control of Movement (21) Flashcards
UMNs in the cerebral cortex control what?
LMNs in the lateral ventral horn contralaterally
distal muscles
UMNs in the brainstem control what?
LMNs in the medial ventral horn contralaterally
(axial muscles)
LMNs in medial ventral horn and lateral ventral horn ipsilaterally
(axial and distal muscles)
Long distance local circuitry neurons interconnect what?
neurons that control axial muscles
Short distance local circuitry neurons control what?
motor nuclei to limb muscles
What does the fact that there are more direct and indirect terminations on the ventral horn motor neurons in some species over others?
more connections = more dexterity
What is the tecto-spinal tract involved with?
axial and midline body orientation
-auditory/visual cues
What is the cortico-rubro-spinal tract involved with?
distal control - mainly arm flexion
What is the cortico-reticulo-spinal tract involved with?
axial and proximal reflexes
-CPG
What is the cortico-vestibulo-spinal tract involved with?
axial and proximal reflexes
-anti-gravity muscles
What the three top areas that neurons from the cortex come from which innervate motor neurons?
M1>secondary motor area > cingulate motor area
Where are the most Betz cells found?
primary motor cortex
What are the 5 requirements to be a cortical motor area?
- projects to motor neurons in spinal cord
- projects to primary motor cortex
- Betz cells
- stimulated at low levels –> movement of discrete muscles
- changes in activity related to parameters of movement
What are the main cortical motor areas?
- primary motor cortex
- Premotor cortex
Lateral - dorsal and ventral
Medial - SMA, CMA
What are the motor association areas?
- Pre-SMA
- parietal & temporal cortex:
dorsal and ventral pathways - prefrontal cortex
What do the corticobulbar tracts control?
facial muscles
What is the result of an UMN lesion of the face?
weakness of inferior facial muscles contralaterally
What is the result of a LMN lesion of the face?
weakness of the entire face ipsilaterally
What does convergence mean when referring to cortical control of movement?
individual muscles are represented in many locations - outputs converge
What does divergence mean when referring to cortical control of movement?
corticalspinal neurons influence multiple neuron pools or different muscles
—synergists usually
If an epileptic surgical resection is too risky what other surgical procedure can you perform?
sub-pial incisions
-preserves motor function
An UMN likely contacts how many pools of LMNs? How many neurons with in these pools?
2-3 - both agonists and antagonists
-all the neurons within each pool
Do more motor neurons change firing properties or only fire in response to certain directions of movement?
most motor neurons respond only to certain movement - very predictable
What is the function of the lateral premotor cortex?
selection of motor responses based on sensory input
What is the function of the medial premotor cortex?
SMA and CMA - execute learned sequences
