Ascending and Descending pathways

Question 1

what pathway serves touch, proprioceptive info and vibration ?

Answer 1

dorsal column-medial lemniscal pathway

Question 2

where do the ipsilateral large sensory axons (Ab) of dorsal column pathway enter first ?

Answer 2

the ipsilateral dorsal column of the spinal cord, the white matter tract medial to the dorsal horn.

Question 3

what information is carried to the brain via the dorsal column pathway

Answer 3

tactile sensation and limb position

Question 4

what is the dorsal column composed of ?

Answer 4

primary sensory axons and second-order axons from neurons in the spinal gray matter.

Question 5

where do the axons of the dorsal column terminate ?

Answer 5

in the dorsal column nuclei, which lie at the junction of the spinal cord and medulla

Question 6

where do the axons from cells of the dorsal column nuclei decussate ?

Answer 6

at the ventral and medial medulla.

Question 7

which tract do axons of the dorsal column nuclei ascend by ?

Answer 7

within a conspicuous white matter tract called the medial lemniscus ?

Question 8

what does the medial lemniscus rise through ?

Answer 8

the medulla, pons, and midbrain

Question 9

which axons of the medial lemniscus synapse with?

Answer 9

with neurons of the ventral posterior (VP) nucleus of the thalamus.

Question 10

where do thalamic neurons project to ?

Answer 10

specific regions of the primary somatosensory cortex, or S1

Question 11

what are the lateral pathways involved in ?

Answer 11

voluntary movement of the distal musculature and are under direct cortical control

Question 12

what are the ventromedial pathways involved in?

Answer 12

control of posture and locomotion and are under brain stem control

Question 13

name two tracts of the lateral pathways ?

Answer 13

corticospinal and ribrospinal tracts

Question 14

what is the longest and largest tract in the CNS ?

Answer 14

the corticospinal tract

Question 15

where do the axons of the corticospinal tract originate ?

Answer 15

in areas 4 and 6 of the frontal lobe, collectively called motor cortex

Question 16

what areas do the axons from the cortex pass through

Answer 16

through the internal capsule, course through the base of the cerebral peduncle (a large collection of axons in the midbrain), then pass through the pons, and collect to form a tract at the base of the medulla

Question 17

how would you describe the medullary pyramid

Answer 17

a tract that forms a bulge, running down the ventral surface of the medulla

Question 18

what is another name for the corticospinal tract ?

Answer 18

the pyramidal tract

Question 19

where does the pyramidal tract decussate ?

Answer 19

at the junction of the medulla and spinal cord. this is known as the pyramidal decussation

Question 20

where do the axons in the corticospinal tract collect in the spinal cord ?

Answer 20

in the lateral column of the spinal cord and form the lateral corticospinal tract

Question 21

where do the corticospinal tract axons terminate ?

Answer 21

in the dorsolateral region of the ventral horns and intermediate grey matter, the location of the motor neurons and interneurons that control the distal muscles. particularly the flexors