NERVOUS SYSTEM AND SENSE ORGANS 33 



192. The vagus nerve (X) is associated with the IXth, 

 along with which it leaves the skull. Outside the 

 skull they expand to form the jugular ganglion and 

 from this they emerge as separate nerves. 



Drawing 16. Draw the brain and cranial nerves from 

 the dorsal aspect (x2). 



Remove the brain by cutting through the cranial nerves, 

 commencing with the olfactory, and place the brain ventral 

 side up. Identify the following structures. 



193. The optic nerves (II) unite in the optic chiasma. 



194. The infundibulum is a bilobed projection, often 

 removed in dissecting, caudal to the chiasma. 



195. Attached to the distal end of the infundibulum, and 

 caudal to it, is the somewhat trilobed pituitary 

 gland, another endocrine organ. 



196. The oculo-motor nerves (III) arise dorsal to the 

 lo^es of the infundibulum and supply certain muscles 

 of the eyeball. 



197. Close to the mid-line of the medulla are the small 

 abducens nerves (VI), each of which after sending 

 a twig to the prootic ganglion proceeds to one of the 

 muscles of the eyeball. 



Drawing 17. Sketch the ventral surface of the brain 

 indicating the nerves that arise from it (x2). 



With a sharp scalpel remove the roof of the brain, noting 

 the following cavities. 



198. In the telencephalon, the lateral ventricles con- 

 nected by the foramen of Monro make up the telo- 

 coele. These are the first and second ventricles. 



199. The foramen communicates with the third ventricle 

 or diaccele in the diencephalon. 



