1300 A MANUAL OF ANATOMY 



Auditory Nerve in the Internal Auditory Meatus. — This nerve 

 passes outwards in the internal auditory meatus in company with 

 the pars intermedia of Wrisberg, the facial nerve, and the internal 

 auditory artery. The facial nerve is placed upon its upper and 

 anterior aspect, and the pars intermedia lies between the two. 

 Two branches connect the auditory nerve with the facial. 



At the deep end of the meatus the auditory nerve breaks up into 

 two divisions — an upper, called the vestibular nerve, and a lower, 

 called the cochlear nerve. The vestibular nerve presents a ganglion, 

 called the ganglion of Scarpa, which is situated at the deep end oi 

 the meatus, its bipolar cells giving origin to the vestibular fibres. 

 Thereafter it breaks up into two parts, upper and lower. The uppei 

 portion furnishes branches which pass to the ampullae of the superior 

 and external semicircular canals, and to the utricle. These pass 

 through the foramina of the superior vestibular area of the upper 

 fossa of the lamina crihrosa at the deep end of the meatus. The 

 lower portion supplies branches to the ampulla of the posterior 



Fig. 539 — Scheme of the Auditory Nerve (Flower). 



C.F. Communicating with Facial E.S.C. To External Semicircular Canal 

 C Cochlear Nerve U. To Utricle 



V. Vestibular Nerve S. To Saccule 



S.S.C. To Superior Semicircular Canal P.S.C. To Posterior Semicircular Canal 



semicircular canal and to the saccule. The former pass through 

 the foramen singulare in the lower fossa of the lamina cribrosa, and 

 the latter through the foramina of the inferior vestibular area of 

 the lower fossa of the lamina cribrosa. 



The branches of the cochlear nerve pass through the foramina 

 of the cochlear area of the lower fossa of the lamina cribrosa. 



Superficial Petrosal Nerves. — The great superficial petrosal nerve is a branch 

 of the geniculate ganglion of the facial in the aqueduct of Fallopius. Aftei 

 emerging from that aqueduct through the hiatus Fallopii, it passes to thi 

 upper part of the foramen lacerum medium. Here it joins the great deej 

 petrosal nerve to form the Vidian nerve, which passes forwards through th< 

 Vidian canal into the spheno-maxillary fossa, and joins the back part oj 

 Meckel's ganglion. I 



The small superficial petrosal nerve issues from the tympanic plexus on thi 

 inner wall of the tympanum, and represents the continuation of the tympani«j 

 branch (nerve of Jacobson) of the petrous ganglion of the glosso-pharyngeai 

 nerve. As it traverses a canal in the petrous portion of the temporal boB' 

 it is joined by a small branch from the geniculate ganglion of the facialj 

 Emerging from this canal through the accessory hiatus, it passes througl 

 the canaliculus innominatus, when present, or through the fissure between 

 the pars petrosa and great wing of the sphenoid, or sometimes through th 

 foramen ovale, into the zygomatic fossa, where it joins the otic ganglion, closi 

 below the foramen ovale. \ 



The external superficial petrosal nerve (inconstant) is a branch of the genicu 



