CEREBRAL NERVES 



243 



maxillary branch of the trigeminal and which innervates the 

 mucous membrane of the pharynx, and (6) chorda tympani, 1 going 

 to the mucous membrane of the floor of the pharynx. These two 

 nerves correspond to the " portio intermedia " of the facial of 

 Mammals (Fig. 182), and are closely related at their origin with 

 the geniculate ganglion. The chorda tympani corresponds to the 



G. trig P. int. m VII 



P. mot I'll 



FIG. 182. DIAGRAM SHOWING THE RELATIONS OF THE PORTIO INTERMEDIA OF 

 THE FACIAL NERVE IN MAN. (After A. F. Dixon ; slightly modified. ) 



/, //, ///, the three branches of the trigeminal ; *, geniculate ganglion of the 

 facial ; t, sphenopalatine ganglion, in the neighbourhood of //; Ch.fy, chorda 

 tympani ; C.t, tympanic cavity, outlined ; G. triy, Gasserian ganglion of 

 the trigeminal ; P.int.mVII, intermediate (sensory) portion of the facial; 

 P. mot. VII, motor portion of the facial (hyomandibular) ; R.liny, lingual 

 branch of///; R.mand, mandibular branch of ///; R.pal, palatine (greater 

 superficial petrosal) branch of facial. The motor portion of trigeminal /// 

 is not indicated. 



prebranchial and the hyomandibular to the postbranchial branch, 

 but from Amphibians onwards the chorda tympani becomes post- 

 spiracular in position. 



III. A main post-spiracular hyomandibular trunk, extending 

 along the hyoid arch, and essentially motor, except for the com- 

 ponents which give rise to the sensory external mandibular and 

 a few twigs supplying the mucous membrane of the spiracle, 



1 The chorda tympani ("alveolar" branch of the facial) passes internally to 

 the lower jaw in Elasmobranchii, Ganoidei, Perennibranchiata, and Anura. In 

 other Amphibians, as in Reptiles, it passes into the bony lower jaw. 



K 2 



