and passes beneath the -emilunar (( lasserian) ganglion into the foramen larermn, 

 where it joins with the groat (loop petrosal nerve to form the Yidian nerve. A lap/' 1 

 part of this nerve consists of sensor] fibres, but it is possible that it may also contain 

 motor fibres. 



(_') A branch of communication parses from the gonicnlum to join the small 

 superficial petrosal nerve in the substance of the temporal bone. The fibres in this 

 communicating branch do not appear to be connected with the cells of the geniciilato 

 ganglion (fig. 704). 



(3) The Nerve to the Stapedius is given off from the facial as it descends in the 

 posterior wall of the tympanum behind the pyramid. 



(4) The Chorda Tympani consists to a very large extent of fibres which are con- 

 nected with the cells of the geniculato ganglion, but it also contains some motor 

 (probably secretory) fibres: it is. therefore, a mixed nerve. It leaves the trunk of 

 the seventh nerve a short distance above the stylo-mast oid foramen, and pursues a 

 slightly recurrent course upwards and forwards in the canaliculus chonhe tympani 

 (iter chords posterius), a minute canal in the posterior wall of the tympanic cavity, 

 and it enters that cavity close to the posterior border of the membrana tympani. It 

 crosses the cavity, running on the inner surface of the tympanic membrane at the 

 junction of its upper and middle thirds, ensheathed in mucous membrane, and passes 

 to the inner side of the manubrium of the malleus above the tendon of the tensor 

 tympani. It leaves the tympanic cavity and passes to the base of the skull through 

 a small foramen (the iter chorda' anterius) at the inner end of the petro-tympanic 

 (Glaserian) fissure. At the base of the skull it inclines downwards and forwards on 

 the inner side of the spine of the sphenoid, which it frequently grooves, and, on the 

 inner side of the pterygoideus externus, it joins the posterior border of the lingual 

 rierve at an acute angle. Some of its fibres leave the lingual nerve and pass to the 

 sub-maxillary ganglion, and others are continued forwards to the tongue. The fibres 

 connected with the tongue are probably afferent fibres associated with the sense of 

 taste, and they are processess of the cells of the geniculate ganglion. Before it joins 

 the lingual nerve the chorda tympani receives a communicating twig from the otic 

 ganglion (figs. 704, 707). 



(5) Usually present is a communicating twig to the vagus, given off at the 

 same level as the chorda tympani, and joining the auricular branch of the pneumo- 

 gastric. While the latter twig is traversing the substance of the temporal bone, 

 it usually receives a filament, the external superficial petrosal, which passes 

 through the hiatus Fallopii and connects the geniculate ganglion with the sym- 

 pathetic plexus on the middle meningeal artery. ' 



(c) After it leaves the skull the seventh nerve gives off two or three collateral 

 branches and two terminal divisions. The collateral branches are the posterior 

 auricular nerve, a branch to the posterior belly of the digastric, and sometimes a 

 lingual branch. The terminal divisions are the temporo-facial and cervico-facial. 



(1) The posterior auricular nerve is the first branch of the extracranial portion 

 of the facial (fig. .705). It passes between the parotid gland and the anterior border 

 of the sterno-mastoid muscle and runs upwards in the deep interval between the 

 external auditory meatus and the mastoid process. In this situation it communi- 

 cates with the auricular branch of the vagus. It supplies the auricularis posterior, 

 sends a slender twig upwards to the auricularis superior, and ends in a long slender 

 branch, the occipital branch, which passes backwards to supply the occipitalis. It 

 also receives filaments from the small occipital and great auricular nerves, and 

 supplies the intrinsic muscles on the inner surface of the pinna. 



(2) The nerve to the posterior belly of the digastric arises from the facial 

 nerve close to the stylo-mastoid foramen and enters the muscle near its centre, or 

 sometimes near its origin. It usually gives off two branches: the nerve to the stylo- 

 hyoid, which somet lines arises directly from the seventh nerve and passes to the upper 

 part of the muscle that it supplies, and the anastomotic branch, which joins the 

 glosso-pharyngeal nerve below its petrous ganglion. 



(3) The lingual branch, first described by Cruveilhier, is not commonly present. 

 It arises a little below the nerve to the stylo-hyoideus and runs downwards and in- 

 wards to the base of the tongue. In its course it passes to the inner sides of the 

 stylo-glossus and stylo-pharyngous, and runs downwards along the anterior border of 

 the latter muscle to the wall of the pharynx. It pierces the superior constrictor, in- 

 sinuates itself between the tonsil and the anterior pillar of the fauces, and it is stated 



02 



