TRIFACIAL NERVE. 185 



dulla oblongata, where the roots divide into three bundles. 

 The anterior bundle passes from behind forward, between 

 the anterior fibres of the pons and the cerebellar portion of 

 the restiform bodies, to anastomose with the auditory nerve. 1 

 The other bundles, which are posterior, pass, the one in the 

 anterior wall of the fourth ventricle to the lateral tract of the 

 medulla oblongata, and the other, becoming grayish in color, 

 to the restiform bodies, from which they may be followed as 

 far as the point of the calamus scriptorius. According to 

 Yulpian, a few fibres from the two sides decussate in the 

 median line in the anterior wall of the fourth ventricle. 2 



From this origin, the large root of the fifth passes ob- 

 liquely upward and forward to the ganglion of Gasser, 

 which is situated in a depression in the petrous portion of 

 the temporal bone on the internal portion of its anterior 

 face. 



The Gasserian ganglion is semilunar in form (sometimes 

 it is called the semilunar ganglion), with its concavity looking 

 upward and inward. 3 At the ganglion, the nerve receives 

 filaments of communication from the carotid plexus of the 

 sympathetic. This anatomical point is of importance in view 

 of some of the remote effects which follow division of the 

 fifth nerve through the ganglion in living animals. 



It will be necessary only to describe in a general way 



HIRSCHFELD, Systeme nerveux, Paris, 1866, p. 166. The anastomo- 

 sis of the auditory nerve has been denied (VFLPIAN, Essai sur Forigine de 

 plusieurs paires des nerfs craniens, These, Paris, 1853, p. 27), but it is admitted 

 by most anatomists. 



2 Op. tit., p. 25. 



3 The structure of this ganglion was first recognized by Gasser, Professor of 

 Anatomy in Vienna. His observations, however, were published by Hirsch, a 

 pupil of Gasser, in 1765 (HiRSCH, Paris quinti Nervorum encephali, Vienme, 

 1765, hi LUDWIG, Scriptores Nevrologiti minores selecti, Lipsiae, 1791, tomus i., p. 

 244, et seq.). Hirsch first gave it the name of Gasserian ganglion (p. 262). 

 Some authors call it the Casserian ganglion, probably confounding Gasser with 

 Casserius. Casserius, in his anatomical figures, describes many parts of the 

 brain and nerves, but says nothing of the gangh'on of the fifth (CASSERIUS, 

 Anatormche Tafeln, Franckfurt am Mayn, 1756). 



