NERVES OF MAMMALIA, 



157 



Ct/ 



Diagram of the ' portio intermedia,' with 

 the ganglionic origin of the ' chorda 

 tympani.' lxxii". 



549). With this ganglion 



of the facial, receives corroboration from the special researches of 



Morganti l into this intricate and difficult part of neurotomy. 

 In the subjoined diagram of the 



result of his dissections, fig. 132, the 



portio intermedia, b, is separated from 



the vestibular division of the acoustic 



c, and from the main trunk of the 



facial «, with both of which it lies in 



close contact. The filament d connects 



b with c, and receives one from the 



latter. Two filaments e connect the 



' intermediate ' with the main portion 



of the facial, a. The intermediate 



portion is resolved into filaments, b, 



before joining the ganglion, g, the 



nature of the ' grey or ash-coloured 



tissue ' of which has been established 



by the microscopic demonstration of 



the ' ganglion-corpuscles ' (lxvi", p 



are connected the superficial petrosal branch of the vidian, h, from 



the spheno-palatine ganglion, and the smaller 



nerve, i, from the f otic ganglion : ' filaments k, 



7, from the facial, «, and the chorda tympani, m. 



Morganti, however, traces a filament n to that 



nerve directly from the facial. 



In the Sheep, fig. 133, the ( portio inter- 

 media ' by is more closely connected, by d, with 

 the acoustic nerve, c ; and sends a shorter and 

 thicker division to the ( geniculate ' ganglion 

 g, by which it is more directly continued into 

 the ' vidian ' branch e ; the \ chorda tympani,' f, being continued 

 mainly from the ganglion, but also, in a smaller degree from the 

 facial, a. The branch from the ' portio intermedia,' b, I described 

 as the 6 vidian ' crossing the ' portio dura,' a. 



The acoustic nerve, fig. 131, 15, rises from the floor of the 

 fourth ventricle, chiefly in connection with grey matter consti- 

 tuting the ' acoustic nucleus.' The nerve consists of an anterior 

 and posterior portion the course of which is more oblique in Man 

 than in most Mammals owing to the great thickness of the cere- 

 bellar crus, ib. 7. In the Cat the posterior root is very large, is 

 a thickened band of fibre from the fusiform cells of the posterior 

 portion of the nucleus ; the band passes along the floor of the 



1 LXX". 



Relations of the chorda 

 tympani and vidian nerve 

 to the ' seventh ' nerve 

 Sheep, magnified twodia 

 meters, lxvi". 



