Descending motor pathways (UMN): pgs 28- 31

Question 1

Neurons whose fibers descend and synapse directly or indirectly (via interneurons) on LMN are ______________________.

Answer 1

Upper motor neurons

Question 2

Where are lower motor neurons located?

Answer 2

In the spinal cord and in the brainstem (some cranial nuclei)

Question 3

T/F - A single LMN receives input from many UMNs.

Answer 3

True

Question 4

Where is the location of the cell bodies in the pyramidal motor system?

Answer 4

UMNs from cerebral cortex

Question 5

What are the tracts that are pyramidal motor system tracts?

Answer 5

1) Corticospinal tract (from cortex to LMNs in spinal cord - Lateral and ventral corticospinal tracts)
2) Corticobulbar tract (from cortex to LMNs in the brainstem)

Question 6

What is the location of the extrapyramidal motor system cell bodies?

Answer 6

UMNs from the brain stem

Question 7

What are the different extrapyramidal motor system tracts?

Answer 7

1) Rubrospinal tract (from red nucleus in midbrain)
2) Vestibulospinal tracts (from vestibular nuclei in the medulla - lateral and medial vestibulospinal tracts)
3) Reticulospinal tract (From reticular formation in the brainstem)

Question 8

The descending corticospinal fibers enter the pyramid of the medulla and 85-90% cross over to the other side of the CNS, and enter the spinal cord to form the ______________________ tract.

Answer 8

Lateral corticospinal tract

Question 9

The small number of fibers of the corticospinal tract (15%) that do not cross enter the spinal ford to form the tiny ___________________________ tract.

Answer 9

Ventral corticospinal tract

Question 10

What is the dominant pathway for voluntary movement?

Answer 10

Lateral corticospinal tract

Question 11

What is the only pathway responsible for skilled, fractionated movements of the distal extremities?

Answer 11

Lateral corticospinal tract

Question 12

Where is the primary motor cortex located?

Answer 12

Frontal lobe: precentral gyrus