CEREBRUM. 



487 



central fissure is such as to form with the longitudinal fissure 

 an angle of about 67 degrees. 



The intra- parietal fissure arises a short distance behind the central 

 fissure. It then runs upward, backward, and downward to 

 terminate near the posterior extremity of the hemisphere. It 

 divides the parietal lobe into a superior and an inferior portion. 



FIG. 220. DIAGRAM SHOWING FISSURES AND CONVOLUTIONS OF THE LEFT SIDE OF 

 THE HUMAN BRAIN. F. Frontal. P. Parietal. O. Occipital. T. Temporo- 

 sphenoidal lobe. S. Fissure of Sylvius. S'. Horizontal. S". Ascending ramus 

 of S. c. Suculs centralis, or fissure of Rolando. A. Ascending frontal, and B. 

 Ascending parietal, convolution. Fj. Superior, F 2 . Middle, and F 3 . Inferior 

 frontal convolutions. f 1 . Superior, f 2 . Inferior, frontal fissures. f 3 . Sulcus prae- 

 centralis. P. Superior parietal lobule. P 2 . Inferior parietal lobule, consisting of 

 P 2 . Supramarginal gyrus, and P 2 '. Angular gyrus. ip. Sulcus interparietalis. 

 cm. Termination of callosomarginal fissure, d- First, O 2 . Second, O 3 . Third, 

 occipital convolutions, po. Parieto-occipital fissure, o. Transverse occipital 

 fissure. 2 . Inferior longitudinal occipital fissure. T t . First, T 2 . Second, T 3 . 

 Temporo-sphenoidal, convolutions. t. First, t 2 . Second, temporo-sphenoidal 

 fissures. (Landois' " Physiology.") 



4. The parieto-occipital fissure, situated on the mesial surface of the 

 hemisphere, divides the latter into a parietal and an occipital 

 lobe. It begins as a deep notch on the surface of the hemisphere, 

 and is then continued downward and forward until it enters the 

 calcarine fissure. 



