Question

The most dorsal (topmost) regions of the human primary motor areas on both hemispheres control movement of:
A) Hands
B) Legs
C) Lips
D) Tongue

Answer 1

Hint: The sensory organization of part of the human body on the sensory cortex is known as the sensory homunculus. It is topographical in the organization, i.e., based on the density and sensitivity of various parts of the body.

Complete answer:
The primary somatosensory area (Brodmann area 3, 1, 2) (PSA) is present in the parietal lobe in the postcentral gyrus.
It is responsible for the initial processing of somatosensory input.
The entire body is represented twice (bilaterally) in the PSA. This topographical representation is known as the sensory homunculus. In this sensory map, the face is represented laterally, hands and upper extremities in the dorsolateral part, lower extremities are represented on the medial surface of the hemisphere.
The sensory representation is respective of the sensitivity of the different parts of the body. The face, lips, hand, fingers are all essential for several skilled activities, hence they have a larger representation in the sensory cortex hemisphere.
The cortical representation of the trunk and back are smaller compared to the other body parts.

So the correct answer is option B) Legs

Notes:
Similar to the sensory homunculus, motor representation also occurs in topographical order. This is known as the motor homunculus.
The motor homunculus is present in the precentral gyrus in the frontal lobe. Representation of feet remains in the top and so does the representation of other body parts.