Exam 2 Study

Question 1

What are the four aspects of somatosensory encoding?

Answer 1

1. Submodality (type of stimulus) 2. Intensity (# of APs, # of axons recruited) 3. Duration and Delta of stim 4. Location: receptive fields (arm vs finger tips)

Question 2

How much do spinal dermatomes overlap?

Answer 2

Approx. 50%. Rarely strict lines of loss on body with just one dermatome lesion

Question 3

What are the five muscle somatosensory receptors?

Answer 3

1a (ms. spindle 1°) 1b (golgi tendon organ) II (ms spindle 2°) III + IV (pain and temperature)

Question 4

What are the cutaneous somatosensory receptors?

Answer 4

Aβ (touch, pressure) Aδ + C (pain and temperature, crude touch)

Question 5

How does myelination change from group 1a –> III + IV?

Answer 5

It decreases from large diameter heavily myelinated fast conductoring ( Ia, Ib, Aβ) to thin myelin (Aδ, III) or unmyelinated (C, IV) and slowly conducting

Question 6

What modality is Aβ?

Answer 6

Touch and pressure

Question 7

What modalities are Aδ and C?

Answer 7

Both are pain & temp and crude touch

Question 8

What modality is III and IV?

Answer 8

Pain, temp in muscles

Question 9

What are the 2 major ascending systems?

Answer 9

Dorsal column-medial lemniscal system Anterolateral system

Question 10

What fibers course through the dorsal column?

Answer 10

Aβ (touch, pressure, vibration

Question 11

How do DC-ML fibers course?

Answer 11

They ascend ipsilaterally through the fasciculus gracilis (medial) and fasciculus cuneatus (lateral)