Descending Motor Pathways Flashcards
Describe the location of the motor cortex and name its three sub areas
Located anterior to central cortical sulcus. 3 sub areas; Primary motor cortex, premotor area and supplementary motor area and some specialised areas within them.
Describe some features of the primary motor cortex
-Topographical representation - Half or the cortex controls hands and muscles of speech - Excitation results in pattern of muscle movement
Describe some of the features of the premotor area
-It has similar topographical representation as primary motor cortex - Nerve signals give rise to more complex patterns of movement
Describe some features of the Supplemental motor area
- Contractions elicited are often bilateral (using both hands) - Usually functions together with premotor area (gives background movement)
Describe some features of the corticospinal tract (what it does, travel of neurons)
- Carries signals from cortex to spinal cord - Neurons travel from cortex to pyramids of medulla and the majority cross in lower medulla. They then travel in lateral corticospinal tracts before terminating on interneurons. - Those neurons that do not cross travel in ventral corticospinal tracts
Describe the features of the lateral pathways
- controlled via cerebral cortex via 2 corticospinal tracts - General control of voluntary movement - Mainly associated with control of distal muscles
Describe some of the features of the ventomedial pathway (where ventral corticospinal pathway is found)
-Controlled in brainstem - Control of posture and rhythmic movements associated with locomotion - Control of axial and proximal muscles
What are the extra pyramidal tracts and their features?
Reticulopsoinal tract - Posture, locomotion and autonomic function Vestibulospinal tract - Balance and posture Rubrospinal tract - From red nucleus and excitatory to flexors Tectospinal tract - head and neck movement for visual tracking.
Posture is adjusted by? and controlled by?
Involuntary movement driven by both predicatively (postural set) and reactively (compensation). It is controlled and driven by brainstem
To maintain posture sensory information is integrated from what?
- Muscle proprioceptors (changes in length or tension) - Sense of balance derived from movements of head relative to earths gravitational feild. - Visual inputs
What are the different nuclei within the brainstem?
Pontine and medullary (mainly counteract each other) and the vestibular nuclei
Describe some of the features of pontine reticular system
- Nuclei transmit excitatory signals down into the cord via pontine reticulospinal tract in anterior column. - Sends high degreee of excitatory signals to extensor muscles and axial muscles
Describe some of the features of the medullary reticular system
- Nuclei transmit inhibitory signals to same anterior motor neurons via medullay reticulospinal tract in lateral column. - Receives strong inputs from corticospinal tract, rubrospinal tract and other motor pathways.
Describe some of the features of the vestibular nuclei
- Function in association with poutine reticular nuceli to control antigravity muscles - Transmit excitatory signals to antigravity muscles via lateral and medial vestibulospinal tracts
What are Upper motor neurons and Lower motor neurons
UMN - Originate in cortex and brainstem nuclei, do not contact muscle LMN - Found in brainstem and spinal cord, motor control to muscles