Which of the following has small representation in somatosensory area of cerebral cortex?

Which of the following has small
representation in somatosensory area of
cerebral cortex ?
a) Lips
b) Thumb/fingers
c) Tongue
d) Trunk
Correct Answer - D
Ans. is ‘d’ i.e., Trunk
A distinct topographic represention of the body can be demonstrated
in somatosensory area-I.
Each side of the cortex receives sensory information from the
opposite side of the body only (contralateral representation).
The body is represented upside down (vertical) in the postcentral
gyms, i.e. the face is represented at the foot of the gyrus whereas
the legs and feet are represented at the top extending on the medial
surface.
Some parts of body like face (especially lips, tongue) and fingers
have a proportionately large representation than the other areas like
the trunk. The cortical representation of the part of the body is
proportionate to its innervation density (number of sensory
receptors) rather than its size.