612 



THE CRANIAL NEKVES. 



ducted towards the tongue. It enters the back part of the tympanic cavity through a 

 short canal emerging below the level of the pyramid, close to the ring of bone giving 

 attachment to the membrane of the tympanum ; and being invested by the mucous lining 

 of the cavity, it is directed forwards across the membrana tympani and the handle of 

 the malleus, to an aperture at the inner end of the Glaserian fissure. It then passes 

 downwards and forwards, under cover of the external pterygoid muscle, and uniting 

 with the gustatory nerve at an acute angle, descends in close contact with it, and is 

 partly distributed to the submaxillary ganglion and partly blended with the gustatory 

 nerve in its distribution to the tongue. As this nerve crosses the tympanum, it is 

 said to supply a twig to the laxator tympaui muscle. 



Fig. 412. Fig. 412. GENICULATE GANGLION OP 



THE FACIAL NERVE AND ITS CONNEC- 

 TIONS FROM ABOVE (from Bidder). 



The dissection is made iu the middle 

 fossa of the skull ou the right side; the 

 temporal bone being removed so as to 

 open the meatus iuteruus, hiatus Fal- 

 lopii, and a part of the caual of the facial 

 nerve, together with the cavity of the 

 tympanum, a, the external ear ; b, 

 middle fossa of the skull with the 

 meningeal artery ramifying in it ; 1 , 

 facial and auditory nerves in the meatus 

 auditorius internus ; 2, large super- 

 ficial petrosal nerve ; 3, small super- 

 ficial petrosal nerve lying over the ten- 

 sor tyrapani muscle ; 4, the external 

 superficial petrosal joining sympathetic 

 twigs on the meningeal artery ; 5, facial 

 and chorda tympani ; b', nerves of the 

 eighth pair. 



The chorda tympani is regarded by 

 some anatomists as a continuation of 

 the great superficial petro.sal nerve. 

 According to Owen, in the horse and 

 calf, the portio dura being less dense 



in structure, the Yidian branch of the fifth may be distinctly seen crossing 

 the nerve after penetrating its sheath, and separating into many filaments, with 

 which filaments of the seventh nerve are blended, Avhile a ganglion is formed 

 by the superaddition of grey matter ; and the chorda tympani is continued partly 

 from this ganglion, partly from the portio dura. (Hunter's Collected Works, vol. iv. 

 p. 194, note.) 



The nerve to the stapedius muscle arises from the trunk of the facial 

 opposite the pyramid, and passes obliquely inwards t j the fleshy belly of 

 the muscle. 



POSTERIOR AURICULAR BRANCH. 



This branch arises close to the stylo-mastoid foramen. In front of the 

 mastoid process, it divides into an auricular and an occipital portion, aud is 

 connected with the great auricular nerve of the cervical plexus. It is said 

 to be joined by the auricular branch of the pneumo-gastric nerve. 



a. The auricular division supplies filaments to the retrahent muscle of 

 the ear, and ends in the integument on the posterior aspect of the 

 auricle. 



6. The occipital branch is directed backwards beneath the small occipital 

 nerve (from the cervical plexus) to the posterior part of the occipito- 



