Ascending Tracts- Dorsal Column: Medial Lemniscus Pathway Flashcards
(25 cards)
Dorsal column medial lemniscal pathway is important for what?
1) Discriminative touch
2) Pressure
3) Vibration
4) Proprioception
What do nuclear chain fibers detect?
The onset of the stretch of the muscle
What do nuclear bag fibers detect?
The progressive stretch of the muscle
What nerve fibers are the most myelinated versus the least?
A > B > C
What does Nerve fiber A(delta) detect?
Fast pain, prick pain
What does Nerve fiber A(alpha) detect?
Muscle spindles in the GTO
What nerve fiber deals with Meissner’s corpuscles, Merkel’s discs, Pacinian corpuscles, Peritrichial nerve endings, and Ruffini corpuscles?
Alpha A(beta)
Where is the first order neuron located?
In the dorsal root ganglion
Where does the tract project to from the DRG?
In the dorsal gray horn
Where does the tract project to from the dorsal gray horn if it is going to a SC below T6?
Gracile fasciculus
Where does GF pick up info from?
Lower limbs (Below T6)
Where does CF pick up info from?
Upper limbs (Above T6)
Where does the tract project to from the dorsal gray horn if it is going to a SC aboveT6?
Cuneate fasciculus
Rank the SC’s input from medial to lateral: Cervical, Thoracic, Lumbar, Sacrum
S L T C
Is the Medial Lemniscus pathway ipsilateral or contralateral after crossing the first order neuron?
Ipsilateral at level of spinal cord
Where is the second order neuron located?
Nucleus Cuneatus or Nucleus Gracilis in the medulla
Is the Medial Lemniscus pathway ipsilateral or contralateral after crossing the second order neuron?
Contralateral
What are the fibers called when they cross over to the other side at the second order neurons?
Internal Arcuate fibers
Where exactly are the internal arcuate fibers crossing?
Dorsal part of medulla behind pyramids
What is the bundle of internal arcuate fibers called as it travels more superior?
Medial lemniscus
Where do the medial lemniscus fibers synapse on?
VPL of thalamus
What are the third order neurons located?
In the VPL
Where do the axons from VPL travel to?
The 1/3 of the posterior limb of the internal capsule
What arteries supply the Posterior limb of the internal capsule?
The Lenticulostriate arteries
