Central Nervous System
Representation in Cerebral cortex is :
- The most likely representation being asked is the representation of body in the somatosensory cortex.
- It is Vertical &upsideQ down called as Sensory homunculusQ.
- Not only is there detailed localization of the fibers from the various parts of the body in the postcentralgyrus, but also the size of the cortical receiving area for impulses from a particular part of the body is proportionate to the use of the partQ.
- The cortical areas for sensation from the trunk and back are smallQ, whereas very large areas are concerned with impulses from the hand and the parts of the mouth concerned with speech.
- LESION OF POST CENTRAL GYRUS
Decreases the sensations, but do not entirely abolish them.
a. Fine touch & proprioception are almost totally lost.
b. Temp. sensibility less affected.
c. Pain sensibility only slightly affected. Q
NOTE:A certain degree of perception is possible in the absence of cortex. Q
- Upon Recovery:
a. Pain sensibility returns first. Q
b. Followed by temperature sense.
c. & finally proprioception & fine touch. Q