Motor Cortex


Terms in this set (...)

describe the function of the motor cortex. In what broadman area is it located? what is the function of the cerebellum?
initiates voluntary movement, amount of force to be exerted, direction of reach, and speed of movement. located in BA 4. The cerebellum is responsible for sensory motor coordination
what are betz cells? where are they found
Betz cells (also known as pyramidal cells of Betz) are giant pyramidal cells (neurons) located within the 5thlayer of the grey matter in the primary motor cortex.
where is the paracentral lobule, what is its function? what is its blood supply?
paracentral lobule is the medial portion of primary motor cortex, based on the cortex homunculus, this area controls our leg muscles. Supplied by the Anterior Cerebral A.
name the 2 premotor areas located anterior to the primary motor cortex. What is their broadman area, and their functions
what happens if premotor areas are damaged?
1. Premotor cortex (PMA)- responsible for the natural, coordinated movements we use in hand shaping and reaching.

2. Supplementary motor area (SMA)- programs sequence of complex movements like playing piano

-->Located in Ba 6, damage leads to Apraxia: inability to perform particular purposiveful actions, combing hair, brushing teeth
what areas receive sensory feedback from movements from body and limbs? what are their BA's? what happens if these sensory areas are damaged?
1. Primary somatic sensory cortex (BA: 1,2,3)
2. Posterior Parietal cortex (BA: 5,7)

--> send information as to how the commands have been executed in order to plan the next movement accordingly.
Impairment of this tract leads to severe clinical signs equivalent to a lesion within the primary motor cortex.
**It is IMPOSSIBLE to move without sensory**
What is the difference between a lesion above or below the pyramids?
1. above the pyramids --> contralateral paralysis of facial and body muscles b/c corticobulbar and corticospinal fibers are affected

2. lesion below pyramids: ipsilateral impairment to the muscles of the body only, not including face
how are extrapyramidal tracts different than pyramidal tracts?
extrapyramidal tracts are motor fibers that are not contained in the pyramids and do not arise from the motor cortex. . Pyramidal neurons regulate the initiation of movements, while the extrapyramidal neurons control and modulate the movements.
.what is the differences between a pyramidal and extrapyramidal lesion?
pyramidal neurons regulate initiation, while EPM control and modulate movements.
Key differences include; 1. involuntary movements i.e. tremors/dystonia for EPM but not corticospinal.
2.Tendon reflexes increased in CST/babinski, not EPM
3. voluntary movement paralysis in CST, only slight in EPM
4. Spastic muscle tone in CST, hypotonia in EPM
what area of the brain is responsible for coordinating eye movements while moving? What is the BA area?
Frontal eye field, part of the motor cortex and is BA 8
what is the purpose of corticofugal tracts?
name the 4 relevant tracts
pathways control motor activity indirectly through cerebellum, basal ganglia, and brainstem, these tracts dont have direct connection with motor neurons
1. corticorubral: flexors of upper body, inhibit enxrensors
2. corticopontine- monitors what goes in/out of cortex
3. corticoreticular: extensors
4. corticostriatal: modulates movements from cortex to spinal cord

*pyramidal pathways like CST, the axon goes all the way to target muscle
describe the 2 types of tremors
1. active tremors: occur when a person attempts a movement

2. passive tremor: occurs when a person is at rest and usually stops when a person attempts a movement
a young athlete experiences weakness in legs. eventually unable to walk. increased reflexes in lower limbs and positive babinski sign
no face symtoms recorded-->rule out lesion in midbrain or pons b/c this would have affected corticobulbar

no lesion in midbrain bc this would have knocked out upper extremity as well

thus this lesion occured bilaterally in the paracentral lobule (medial portion of primary motor cortex)