340 NERVOUS SYSTEM. 7 
In the following account of the brain of the cat all parts 
will be described as far as possible in relation with the tubular 
structure of the brain. The brain will be considered as a 
hollow structure, having central cavities, and the solid portions 
will be. brought into relation as parts of the roof, sides, or floor 
of the cavities. The cavities of the brain, forming a direct 
continuation of the central canal of the spinal cord, are known 
as ventricles (ventriculi). 
In a‘general view of the cat’s brain from the dorsal side 
(Fig. 137) four subdivisions are discernible. At the caudal 
Fic. 137.—DoRSAL SURFACE OF THE BRAIN. 
J, olfactory bulbs; Z/, cerebral hemispheres; 7/7, cerebellum; /V, medulla. a, 
preesylvian sulcus; 4, cruciate sulcus; ¢, sulcus ansatus; @, coronal sulcus; ¢, anterior 
sulcus; 7, posterior sulcus; g, suprasylvian sulcus; %, separate parts of the lateral 
sulcus; 2, end of splenial sulcus; 7, vermis of cerebellum; 2, hemispheres of cerebel- 
lum; /, roof of fourth ventricle; ™, first cervical nerve, 1, orbital lobe (or gyrus); 
2, sigmoid gyrus; 3, anterior sylvian gyrus; 4, ectosylvian gyrus; 5, suprasylvian 
gyrus; 6, posterior sylvian gyrus; 7, parts of marginal gyrus; 8, gyrus compositus 
posterior. 
end is a small stalk-like portion (7V) which is clearly a slightly 
modified continuation of the spinal cord; this is the myelen- 
cephalon or medulla oblongata. Just craniad of this, rising 
