370 ELEMENTARY ANATOMY. [LESS. 



6. Thus, if the whole organ be VERTICALLY BISECTED in 

 the line of the longitudinal fissure, we find as follows : 

 The inner surface of the cerebral hemisphere in view is 



FIG. 325. SIDE VIEW OF THE BRAIN AND UPPER PART OF THE SPINAL MARROW 

 in place, the parts which cover the cerebro-spinal centres being removed. 



a, front part of atlas vertebra applied to the odontoid process (o) behind it ; b, body 

 of third cervical vertebra ; c, cerebrum the long continuous groove imme- 

 diately above the convolution tO'which the letter c points, is the Sylvianfissure, 

 while the convolution itself forms part of the temporal lobe of the cerebrum ; 

 cB, cerebellum : m, medulla oblongata ; p, pons Varolii ; s, arch of skull cut 

 through ; s', spinous process of axis vertebra. 



very much convoluted, and the cerebrum may be seen to 

 extend beyond the olfactory lobe in front and beyond the 

 cerebellum behind. 



Beneath the middle of the cerebrum we come to the cut 

 surface of the corpus callosum, the front part of which 

 bends sharply backwards and downwards, forming what is 

 called the knee (gemi). Beneath the bent-back extremity of 

 the corpus callosum is the cut edge of the lamina cinerea (or 

 terminalis). At the upper part of this lamina we find the 

 cut surface of a transversely-extending white cord, called the 

 anterior commissure, and immediately behind the lamina we 

 find another cord, part of what is called the fornioc. This 

 latter structure extends, not transversely, but at first upwards 

 and forwards, afterwards curving backwards it passes to the 

 hinder part of the corpus callosum. Filling up the space 

 between the corpus callosum and fornix is a delicate membrane 

 called the septum lucidum. 



Below the fornix we have evidently cut into a cavity ex- 



