STUDY OF STRUCTURE OF CENTRAL NERVOUS SYSTEM. 13 



IV. Separating the cerebellum from the cerebrum, note in bending backwards 



and outwards, the brachium conjunctivum of the cerebellum. 



1. The anterior velum attached laterally to these. 



2. The IV. nerve leaving the brain through the anterior velum and passing out 



across the peduncles. 



V. At the side, immediately in front of the V. nerve, the hrachium of the pons 



continuous below with the transverse pons fibers. 



Now cut through the brachium of the pons and the brachium con- 

 junctivum, enter the substance of the cerebelkim and continuing to cut- 

 backwards remove the cerebellum. 



I. Note the cut surface of the brachium conjunctivum, the brachiurii of the pons, 



and the restiform bodies. 



II. Make a cut through the cerebellum parallel to the median cut surface, passing 



through the brachia and note: 



1. The arrangement of the white matter. 



2. In the white matter a patch of grayish matter the dentate nucleus. 



In the medulla observe: 



I. TTie posterior funiculi of the cord. 



II. These are continuous above with a spindle-shaped enlargement bending out- 



wards, the clava. 



III. The restiform body. 



IV. The fourth ventricle. 



In the midbrain region : 



I. The aqueduct of the cerebrum (Sylvius). 



II. Tile superior hillocks of the quadrigeminal bodies. 



On the outer surface of the midbrain note : 



III. A band of white fibers passing forward and downward from the inferior 



hillocks, the inferior brachium. 



IV. This (III) ends anteriorly as a large swelling, the medial geniculate body. 



V. Note the fibers of the optic tract covering the anterior portion of the side 



of the midbrain and concealing the superior hrachium and the laterial 

 geniculate body. 



VI. In front of the optic tract is the posterior extremity (pulvinar) of the optic 



thalamus. 



VII. Anteriorly tlie front part of the entrance to the aqueduct of the cerebrum, 



the roof of the III ventricle, bends somewhat ventrally and then returns 

 upon itself. At the lowest point of the bend is the posterior commissure. 

 VIIT. The upward bend of the roof in front of the posterior commissure is the 

 posterior part of the habenula, a round, or elongated body. 



IX. At the summit of the habenula is the pineal body or epiphysis. 



X. Passing from behind forward over the epiphysis is a bunch of vessels which 



join the roof of the III ventricle in front of the epiphysis and pass forward 

 in it. Tliis is the choroid plexus of the III ventricle and the portion of the 

 roof of the ventricle in which it lies is the velum interpositum. 



