Module 4: Somatosensory Pathways

Question 1

Somatosensory

Answer 1

Refers to the sensations of touch, pain, temperature, vibration, and proprioception

Question 2

Posterior column-medial lemniscal pathway conveys which somatosensory abilities?

Answer 2

proprioception
vibration sense
fine, discriminative touch

Question 3

Proprioception

Answer 3

awareness of the position of one’s limb/joint

Question 4

Anterolateral/ventrolateral pathways include which tracts?

Answer 4

spinothalamic and associated tracts

Question 5

The anterolateral/ventrolateral pathways are responsible for which somatosensory abilities?

Answer 5

pain
temperature sense
crude touch

Question 6

T or F: Since some aspects of touch sensation are carried by both pathways, touch sensation is not eliminated completely in isolated lesions to either pathway.

Answer 6

T

Question 7

4 types of sensory neuron fibers

Answer 7

A-alpha (13-20µm)
A-beta (6-12µm)
A-gamma (1-5µm)
unmyelinated C’s (0.2-1.5µm)

Question 8

What sensory modalities are conducted most quickly?

Answer 8

proprioception (A-alpha & A-beta)
superficial touch (A-beta)
deep touch (A-beta)
vibrations (A-beta)

Question 9

What sensory modalities are conducted most slowly?

Answer 9

pain (A-gamma)
cool temperature (A-gamma)
pain (C)
warm temperature (C)
itch (C)

Question 10

What do the A-alpha’s conduct?

Answer 10

proprioception

Question 11

What do the A-beta’s conduct?

Answer 11

proprioception
superficial touch
deep touch
vibrations

Question 12

What do the A-gamma’s conduct?

Answer 12

pain

temperature (cool)

Question 13

What do the unmyelinated C’s conduct?

Answer 13

pain
temperature (warm)
itch

Question 14

Where are sensory neuron cell bodies located?

Answer 14

dorsal root ganglia

Question 15

What are the functions of each of the bifurcated dorsal root ganglion stem cell axons?

Answer 15

A) convey sensory information from the periphery

B) carry information to the spinal cord through the dorsal nerve roots

Question 16

dermatome

Answer 16

A peripheral region innervated by sensory fibers from a single nerve root level

Question 17

Sensation for the face is provided by which cranial nerve?

Answer 17

CN V, trigeminal nerve

Question 18

Sensations for most of the head (excluding the face) are provided by nerve roots at what level?

Answer 18

C2

Question 19

What are the two main somatosensory pathways?

Answer 19

posterior column-medial lemniscal pathway.