Author Question: 8-115. Explain what is meant by the term motor homunculus. What will be an ideal ... (Read 89 times)

lidoalex · **on:** Jun 22, 2018

8-115. Explain what is meant by the term motor homunculus.

What will be an ideal response?

Question 2

Describe and give an example of (a) flexion and (b) extension of a limb produced by muscles.

What will be an ideal response?

LP · **Reply #1 on:** Jun 22, 2018

Answer to Question 1

Answer: The primary motor cortex lies just before the central sulcus on each hemisphere. The motor cortex is organized in a topical fashion such that activation of certain patches of cortex results in movements of particular parts of the body. The homunculus is a cartoon representation of the topical organization of the motor cortex. In effect, it resembles an upside down person with the legs over the top of the cortex and the face at the bottom of the motor strip.

Answer to Question 2

Answer: Contraction of a flexor muscle produces flexion, which draws in a limb toward the body. Contraction of an extensor muscle moves a limb out from the body (antigravity action). A four-legged animal lifts its paw by contracting the flexors and places the paw back down by contracting the extensors.