The Sensory Area

The portions of the cerebrum involved in cutaneous and muscular sensibility embrace the posterior portion of the parietal convolutions, the precuneus or quadrate lobule, and gyrus fornicatus as far forward as the motor area on the medial aspect.

The visual area embraces the occipital lobe, particularly its cuneus lobule, and region of the calcarine fissure on the medial surface of the hemisphere. The anterior portion of the occipital lobe and the region of the angular gyrus are concerned in the more complex phenomena of sight, and their destruction produces word-blindness. Destruction of the centres on both sides produces what has been called mind-blindness, because objects can no longer be recognized.

Fig. 46.   Foreshortened view showing corpus striatum, thalamus, corpora quadrigemina, lateral, third, and fourth ventricles, etc.

Fig. 46. - Foreshortened view showing corpus striatum, thalamus, corpora quadrigemina, lateral, third, and fourth ventricles, etc.

The Auditory Area

The centre for hearing is located in the superior and middle temporosphenoidal convolutions. It requires destruction of these convolutions on both sides of the brain to produce total cerebral deafness. The memory or recognition of spoken words (word hearing) is apparently performed by the posterior ends of the superior and middle (1st and 2d) temporosphenoidal convolutions.

Gustatory Area

The sense of taste is supposed to be located on the under and inner surfaces of the temporosphenoidal lobe or fourth temporal convolution.

Olfactory Area

The sense of smell is supposed to involve the anterior portion of the gyrus fornicatus and the upper medial portion of the temporosphenoidal lobe.

The cerebral areas for both smell and taste have not been as yet accurately determined.