Neuroscience Cortical Control of Movement Frank A. Middleton Flashcards
Direct cortico-motor innervation develops when?
Postnatally - increase in dexterity - increase in white matter tracts
Which develops first– intrinsic fine motor control of individual fingers, or extrinsic hand control?
Extrinsic hand control
Name the indirect descending pathways, projections to a midbrain or brain stem center, then to the spinal cord.
- Tectospinal, aka cortico-colliculo spinal
- Cortico-rubro spinal
- Cortico-reticulo spinal
- Cortico-vestibulo spinal
Name the direct descending pathways, connections from large pyramidal cells in layer 3 and 5 to the ventral spinal cord.
- Lateral cortico-spinal
2. Medial cortico-spinal
The reticulospinal tract is involved with:
reflexes
Antigravity muscles are supplied by what innervation?
Lateral and medial vestibulospinal tracts
Axial and midline body operation is innvervated by:
Colliculospinal tract
The rubrospinal tract innervated what muscles and actions?
Some distal control, mainly arm flexion
Betz cells are what kind of cells?
pyramidal cells
Why are Betz cells so big?
They have extremely long axons that project all the way down the spinal cord.
Where can the most Betz cells be found?
Motor areas
Where is the primary motor cortex?
Lateral and medial surfaces of the premotor cortex
The lateral premotor cortex is made up of:
PMd, dorsal premotor area
PMv, ventral premotor area
The medial premotor cortex is made up of:
SMA, supplementary motor cortex
CMA, cingulate motor areas
T or F: The cortical motor area projects to motor neurons in the spinal cord, either directly or indirectly.
True
T or F: The cortical motor area projects to the primary somatosensory cortex.
FALSE. the cma projects to the primary MOTOR cortex
T or F: The cortical motor area contains Betz cells.
True, or other large layer V projection neurons
T or F: The cortical motor area can be stimulated at low thresholds to produce movements of discrete muscles or muscle groups.
True
T or F: The cortical motor area does not display changes in activity related to parameters of movement.
False. CMA do display changes in activity related to parameters of movement.
Decerebrate posturing suggests a lesion above or below the red nucleus?
Below (could be brain stem or pontine stroke)
Based on experimental data, two key features have emerged for understanding the role of the cortical motor areas in motor control:
- Individual muscles are represented in multiple locations.
2. Individual corticospinal neurons diverge to influence multiple motor neuron pools, and hence multiple muscles.
Cortical motor cells code for:
- Direction. Individual neurons increase discharge rate for certain directions (ie finger pointing) more than others.
- Force
- Muscle activity
T or F: The motor cortex does not act alone.
True - Prefrontel, Pre-SMA, SMA, CMA, PMd, PMv, M1, all play a role
UMN or LMN: Loss of fine voluntary movements
UMN
UMN or LMN: Clonus
UMN
UMN or LMN: Decreased superficial reflexes
LMN
Lesion above Red Nucleus might involve what structures, and what posturing?
Decorticate posturing, cortex or internal capsule
In decorticate posturing, why are legs extended and feet turned inward?
Due to disinhibition of RST and loss of corticospinal flexor tone in legs
