Somatosensory System

Question 0

Receptive fields

Answer 0

Larger receptive fields for areas of skin that don’t need fine resolution.
For finer tactile sensation multiple small receptive fields, packed closely.

Question 1

Somatosensory

Answer 1

“Body sense”
• Pain
• Temperature
• Simple touch
• Proprioception (perception of position)
• Kinesthesia (perception of movement)
• Stereognosis (perception of size and shape of objects by touch).
• Somatosensory afferents feed into reflexes and also distribute to cerebral cortex and cerebellum.

Question 2

Sensory pathways

Answer 2

Cell bodies of the first afferent neuron for all pathways is located in the DRG
Typically cross the midline => contralateral.
Travel via medial lemniscus through the thalamus to postcentral gyrus.

Question 3

Anterior (ventral) spinothalamic

Answer 3

crude (non-discriminative) touch

Question 4

Lateral spinothalamic

Answer 4

itch, pain & temperature

Question 5

Fasciculus gracilis

Answer 5

fine touch, pressure, vibration, conscious proprioception of lower limb

Question 6

Fasciculus cuneatus

Answer 6

fine touch, pressure, vibration conscious proprioception of upper limb

Question 7

Spinocerebellar

Answer 7

unconscious proprioception from muscle spindles/tendon organs/joint & skin receptors to cerebellum