L9 Somatosensory Pathways I

Question 1

1. What stimulus is detected by the Meissner’s Corpuscle?

Answer 1

Stroking, changes in texture, flutter (around 50 Hz)

Question 2

2. What stimulus is detected by the Pacinian Corpuscle?

Answer 2

Vibration (about 200-300 Hz)

Question 3

3. What stimulus is detected by the Merkel’s Disc?

Answer 3

Sustained light touch and pressure

Question 4

4. What stimulus is detected by the Ruffini’s Endings?

Answer 4

Pressure and stretch, deep in the skin

Question 5

5. What stimulus is detected by the Free Nerve Endings?

Answer 5

Touch, pressure, stretch, itch, pain, temperature

Question 6

6. What stimulus is detected by the Hair Follicle Receptors?

Answer 6

Touch: Movement of Hair

Question 7

7. Sensory information from the mechanoreceptors comes in through the ventral root.

True or false?

Answer 7

False

Info comes in via the dorsal root.

Note: it does not synapse in the in the DRG - goes straight into the dorsal horn.

Question 8

8. Describe the sensory organisation of the Spinal Cord.

Answer 8

Myelinated A-beta axons enter the dorsal horn and branch.

• synapses onto 2nd order neurons in laminae III-V
• unconscious reflexes

Ascends in the dorsal column tract (gracile, cuneate)

• discriminative touch
• conscious proprioception (to S1)

Lower limbs in gracile fasciculus

• whilst thoracic/cervical part of sensory - cuneate fasciculus
  
  • below T6 - no cuneate fasciculus however