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CEREBRUM. 



anterior and posterior fissures into symmetrical halves, and each 

 half consists of three different parts. 



Corpus, pyramidak. — This is a narrow, cylindrical portion, re- 

 sembling a cord, and situated in front. It communicates freely with 

 its fellow, by a decussation of their fibres, about one inch from the 

 pons. 



Corpus olivare. — This is an oval, convex mass, behind the corpus 

 pyramidale, from which it is separated by a fissure. It is about half 

 an inch in length. A section of it exhibits an arrangement of cine- 

 ritious matter called cm-pus Jimhriatwni, 



Corpus restiforme is the posterior division of each lateral column, 

 and is separated from the corpus olivare by a groove. Between it 

 and its fellow is a continuation of the posterior fissure called cala- 

 mus scriptorius, across which pass transverse fibres of medullary 

 matter. 



PONS VAROLII. 



This is formed of medullary matter, and is cuboidal in shape. 

 Externally, the fibres are transverse ; internally, they are longitu- 

 dinal, being a continuation of those of the medulla oblongata. It 

 is situated in front of the medulla oblongata, and rests upon the 

 basilar process. From it proceed four crura. 



CEREBRUM. 



The cerebrum is an oval mass, weighing from three to four 

 pounds, and divided into two hemispheres by the superior longitudi- 

 nal fissure. Each hemisphere consists of an anterior, middle, and 

 posterior lobe. The anterior and middle lobes are separated by the 

 fissure of Sylvius. The division between the middle and posterior, 

 is an imaginary line in front of the anterior edge of the cerebellum. 

 The surface presents a number o^ gyri, or convolutions, each sepa- 

 rated by deep sulci, or fissures. The interior of each hemisphere is 

 medullary, and the surface of each convolution is cineritious for 

 the depth of one to two lines. 



Crura Cerebri^ are two thick, cylindrical white cords, which diverge 

 from the anterior border of the pons, and their fibres terminate in 

 the hemispheres of the brain. In a triangular space between them, 

 is a layer of medullarjL matter called the locus perforatus. 



Emi7ientice Mammilla res, are two white, globular bqdies, about 

 the size of a pea, situated between the crura of the brain, and in 

 front of the locus perforatus. 



Tuber Cinereum, is a soft, gray mass, in front of the eminentiae 

 mammillares, and behind the chiasm of the optic nerves. 



Infmidibulum, is a hollow, conical body, of a reddish colour, with 

 its base upon the tuber cinereum, and its apex attached to \\\e pitui- 

 tary gland. 



