Light Touch Pathway

Question 1

Light Touch Pathway Receptors

Answer 1

Hair follicle receptors (follicular ending)
Ruffini ending
Merkel complex
Meissener corpuscles
Pacinian corpuscles

Question 2

Dorsal column-medial lemniscus system has?

Answer 2

Two different tracts (one is actually a column, one is called a lemniscus)
One column in the spinal cord
One lemniscus in the brainstem

Delta first-order afferent neuron

Question 3

Light Touch Pathway Spinal Cord

Answer 3

Dorsal column

• Two parallel fasciculi, but you are only responsible for knowing the name of the column as a whole
• Posteromedial in the spinal cord
• Not present in the brainstem

Question 4

Light Touch Pathway Brainstem

Answer 4

Medial lemnicus

• Anteromedial in the medulla and caudal pons
• Gradually moves more lateral in the mid-to-rostal brainstem
• Not present in the spinal cord

Question 5

Light touch receptor is stimulated and?

Answer 5

an AP potential is generated and propagates along an Beta first-order afferent (whose soma is in a DRG). Central axon travels up the dorsal column to a caudal medulla.

Question 6

First-order afferent synapses with what?

Answer 6

A second-order neuron in a nucleus in the caudal medulla. The second-order neuron crosses to the contralateral anteromedial medulla and travels up in the medial lemniscus to the VPL nucleus of the thalamus

Question 7

Second-order neuron synapses with?

Answer 7

The third-order neuron in the VPL nucleus of the thalamus and the third-order neuron goes to the primary somatosensory cortex of the parietal lobe and light touch perception occurs.