36 ANATOMY OF THE HEAD AND NECK. 



These branches, as well as that portion of the main trunk lying in 

 the infra-orbital canal, cannot of course be seen without the removal 

 of the eyeball. 



The inferior maxillary nerve is the longest, and the most inferior in 

 point of position of the three trunks into which the fifth pair divides ; 

 as it passes out through the foramen ovale it is joined by the second 

 primary root of the fifth nerve, which lies behind the ganglion ; it 

 then divides into muscular, the gustatory, the inferior dental, and 

 the auriculo-temporal branches. 



The SIXTH, or ABDUCENS NERVE, pierces the dura mater 

 on the clivus Blumenbachii of the sphenoid bone ; it crosses 

 the cavernous sinus, enters the orbit through the sphenoidal 

 fissure, and passes between the two heads of the external 

 rectus or abducens muscle, to which it is distributed. 



The SEVENTH PAIR consists of two nerves, the FACIAL 

 and the AUDITORY ; the facial is called the portio dura, the 

 auditory the portio mollis, the former being of a dense, the 

 latter of a soft and pulpy structure. Both of these nerves 

 enter the temporal bone at the meatus auditorius interims. 



In order to study these nerves properly, a temporal bone should be 

 immersed in strong alcohol, and afterward softened in hydrochloric 

 acid ; it can then be cut with a knife, and its canals followed out. 



The facial nerve is the smallest of the two trunks ; after 

 entering the meatus auditorius internus, it passes through 

 the aqueduct of Fallopius and emerges at the stylo-mastoid 

 foramen ; it there divides into two branches, the temporo- 

 facial and the cervico-facial ; these have been already de- 

 scribed (p. 23). While in the aqueduct of Fallopius, this 

 nerve forms a ganglionic enlargement, called the intumes- 

 centia gangliformis. A small branch of the Yidian nerve, 

 which passes backward beneath the Gasserian ganglion, 

 enters the hiatus Fallopii to join the intumescentia ; this is 

 called the superficial petrosal nerve. 



* The auditory nerve enters the meatus auditorius inter- 

 nus, and dividing into two branches, the cochlear and vesti- 

 bular, is distributed to the internal auditory apparatus. 



The EIGHTH PAIR is composed of three nerves, the 

 GLOSSO-PHARYNGEAL, PNEUMOGASTRIC, and SPINAL ACCES- 

 SORY ; these all pass out at the foramen lacerum posterius. 



The glosso-pharyngeal nerve passes through a distinct 

 canal of the dura mater in the above-named foramen, and lies 

 at its innermost extremity. That portion of the nerve lying 

 in the jugular fossa presents two gangliform swellings, the 

 superior being called the ganglion jug ulare and the inferior 



