Ascending Tracts- Dorsal Column: Medial Lemniscus Pathway

Question 1

Dorsal column medial lemniscal pathway is important for what?

Answer 1

1) Discriminative touch
2) Pressure
3) Vibration
4) Proprioception

Question 2

What do nuclear chain fibers detect?

Answer 2

The onset of the stretch of the muscle

Question 3

What do nuclear bag fibers detect?

Answer 3

The progressive stretch of the muscle

Question 4

What nerve fibers are the most myelinated versus the least?

Answer 4

A > B > C

Question 5

What does Nerve fiber A(delta) detect?

Answer 5

Fast pain, prick pain

Question 6

What does Nerve fiber A(alpha) detect?

Answer 6

Muscle spindles in the GTO

Question 7

What nerve fiber deals with Meissner’s corpuscles, Merkel’s discs, Pacinian corpuscles, Peritrichial nerve endings, and Ruffini corpuscles?

Answer 7

Alpha A(beta)

Question 8

Where is the first order neuron located?

Answer 8

In the dorsal root ganglion

Question 9

Where does the tract project to from the DRG?

Answer 9

In the dorsal gray horn

Question 10

Where does the tract project to from the dorsal gray horn if it is going to a SC below T6?

Answer 10

Gracile fasciculus

Question 11

Where does GF pick up info from?

Answer 11

Lower limbs (Below T6)

Question 12

Where does CF pick up info from?

Answer 12

Upper limbs (Above T6)

Question 13

Where does the tract project to from the dorsal gray horn if it is going to a SC aboveT6?

Answer 13

Cuneate fasciculus

Question 14

Rank the SC’s input from medial to lateral: Cervical, Thoracic, Lumbar, Sacrum

Answer 14

S L T C

Question 15

Is the Medial Lemniscus pathway ipsilateral or contralateral after crossing the first order neuron?

Answer 15

Ipsilateral at level of spinal cord

Question 16

Where is the second order neuron located?

Answer 16

Nucleus Cuneatus or Nucleus Gracilis in the medulla

Question 17

Is the Medial Lemniscus pathway ipsilateral or contralateral after crossing the second order neuron?

Answer 17

Contralateral

Question 18

What are the fibers called when they cross over to the other side at the second order neurons?

Answer 18

Internal Arcuate fibers

Question 19

Where exactly are the internal arcuate fibers crossing?

Answer 19

Dorsal part of medulla behind pyramids

Question 20

What is the bundle of internal arcuate fibers called as it travels more superior?

Answer 20

Medial lemniscus

Question 21

Where do the medial lemniscus fibers synapse on?

Answer 21

VPL of thalamus

Question 22

What are the third order neurons located?

Answer 22

In the VPL

Question 23

Where do the axons from VPL travel to?

Answer 23

The 1/3 of the posterior limb of the internal capsule

Question 24

What arteries supply the Posterior limb of the internal capsule?

Answer 24

The Lenticulostriate arteries

Question 25

Where do the fibers travel to from the 1/3 of the posterior limb of the internal capsule?

Answer 25

Postcentral gyrus of the cerebral cortex