360 NERVOUS SYSTEM. 



elevated : the optic nerves also cross them obliquely at their fore 

 part. 



In regard to texture, the crus cerebri presents, on its under 

 surface, a medullary layer of two lines in thickness; to this suc- 

 ceeds a parcel of cineritious matter, which, on being removed, 

 is followed by a mixture of both cineritious and white matter, 

 more abundant than either of the preceding. 







The Eminentise Mammillares, or Corpora Albicantia, are 

 two small bodies, one on each side, about the size of a French 

 pea. They are situated near the anterior extremities of the 

 crura cerebri, on their internal faces, and almost in contact 

 with each other. Their texture is medullary without, and cor- 

 tical within. 



The Infundibulum is placed immediately before the eminen- 

 tiae mammillares. It is a flattened conoidal body, half an inch 

 long, with its base upwards, and its apex going downwards and 

 forwards. It is formed of cineritious matter. Most generally 

 its base is hollow, and opens into the third ventricle, but its point 

 is closed. J. F. Meckel, however, asserts that a communication 

 exists entirely through it, from the pituitary gland to the third 

 ventricle, and that he has frequently proved it by passing air or 

 liquids from this gland, though the experiment does not succeed 

 when he attempts the injection from the third ventricle. 



The Pituitary Gland (Glandula Piluitaria) is situated in the 

 Sella Turcica, and is covered so completely by the dura mater, 

 that only a small aperture is left for the point of the infundibu- 

 lum to pass through and to adhere to it. It is an ovoidal body, 

 the greatest diameter of which is transverse, and amounts to 

 six lines. It is partially divided, so as to give the appearance 

 of two lobes, of which the anterior is much the larger. It is 

 hard and cineritious, with a small quantity of medullary matter 

 within. In either side of it there is a depression from which 

 leads a small canal towards the place where the infundibulum 

 joins it: the two canals are, in the latter place united into one. 

 In some very rare cases, gritty matter has been found in it, 

 as there is in the pineal gland. It is also surrounded by pia 

 mater. 



