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inward beneath the root of the trifacial nerve and the caput cornu, 

 to a group of large multipolar cells, which lies near the surface of 

 the fourth ventricle, on each side of the median furrow, and which 

 gives origin also to the sixth nerve. 



The transverse fibres of the pons Varolii are an extension of the 

 arciform fibres of the medulla oblongata. The grey substance of 

 the pons is arranged in a peculiar manner. Its cells are generally 

 round> oval, and fusiform, of about the 1500th of an inch in dia- 

 meter, and are so connected with nerve-fibres, in chains or bundles, 

 as to form a complete network. The principal chains of this network 

 have, in general, a longitudinal extension, and follow the course of 

 the longitudinal fasciculi of the anterior pyramids, from the sides of 

 which they send off processes across the transverse bundles, in which, 

 as well as around the longitudinal bundles of the pyramids, the cells 

 are at intervals collected into groups of variable size and shape. 



The trifacial or fifth nerve originates from a somewhat conical 

 eminence of grey substance, which is situate immediately behind the 

 fossa where the anterior fibres of the pons Varolii meet the point of 

 the fillet, at the upper edge of the middle peduncle of the cerebellum. 

 This grey mass consists of three distinct nuclei in close apposition. 

 Its outer portion is the caput cornu posterioris, or dilated extremity 

 of the posterior cornu, and is composed of several groups of small 

 round and oval cells, of about the 1500th of an inch in diameter, to- 

 gether with numerous longitudinal bundles of nerve-fibres. The 

 posterior portion of the grey mass overlies, and is continuous with, 

 the root of the caput cornu. It is the upward extension of the inner 

 nucleus of the auditory nerve, and contains many cells of a larger 

 kind. The inner side of the mass consists of an oval group of large 

 multipolar cells of the same shape and size as those of the anterior 

 cornu of the medulla spinalis. The large root of the fifth nerve 

 may be divided into three parts, two of which originate in the conical 

 mass just described ; of these two, the larger arises from the caput 

 cornu posterioris, while the fibres of the smaller may be traced back- 

 ward to the continuation of the auditory ganglion, which overlies 

 the cornu. These latter are probably the fibres which go to form 

 the gustatory branch of the fifth nerve ; for it was formerly shown 

 that the commencement or lowest part of the auditory ganglion 

 was the principal origin of the glosso-pharyngeal nerve. The third 

 VOL. xi. 2 D 



