SEVENTH PAIR OF NERVES. 



547 



in close proximity to the artery which bears 

 the same name. The remaining branch of the 

 nerve takes a vertical direction, ascending 

 perpendicularly behind the ear through the 

 fleshy bundles of the retrahens aurem. To 

 this muscle it is chiefly distributed ; but a few 

 of its filaments continue to the posterior sur- 

 face of the auricle, probably to supply its 

 transverse muscular fibres. The trunk of the 

 posterior auricular nerve, or some one of 

 these its branches, is usually found to be 

 joined by filaments of the great auricular 

 nerve from the cervical plexus, and more 

 rarely by some twigs from the lesser occi- 

 pital branch of the same plexus. Arnold 

 also describes a filament of the auricular of 

 the pneumogastric uniting with it. 



The two following branches not unfre- 

 quently arise by a common trunk. The di- 

 gastric, the larger of the two, leaves the facial 

 nerve to penetrate the posterior belly of the 

 digastric muscle, and supply it with many 

 filaments. One of its branches, of more con- 

 siderable magnitude, perforates its substance, 

 and passing directly inwards, joins the glosso- 

 pharyngeal immediately on its emergence from 

 the skull. Other filaments of smaller size are 

 said to join the superior laryngeal of the pneu- 

 mogastric. 



The stylo-hyoid branch, leaving the trunk of 

 the portio dura near the preceding, passes 

 downwards, forwards, and inwards ; crossing 

 the styloid process obliquely, then running 

 along the upper border of the muscle, and 

 finally penetrating its fibres to be distributed 

 to its interior. It is believed to unite, by nu- 

 merous minute twigs, with the sympathetic 

 around the neighbouring carotid vessels. 



At the place of its division, the nerve occu- 

 pies a position in the parotid gland which is 

 superficial to the many other vessels and 

 nerves found here ; and especially, at right 

 angles to the external jugular vein and carotid 

 artery. 



The temporo-facial division or branch is larger 

 than the cervico-facial ; it passes forwards and 

 upwards over the condyle of the lower jaw, 

 and joins, towards the zygoma, with one or 

 two large branches of the auriculo-temporal 

 nerve. This comes from the third division of 

 the fifth in the pterygoid fossa ; and the place 

 of its union with the portio dura is in close 

 proximity to the external carotid artery. The 

 intimacy of the junction which connects the 

 two nerves has probably led some anatomists 

 to describe this temporo-facial branch as giving 

 many filaments to the front of the ear. These, 

 however, with many others which ramify in 

 the gland itself, belong to the associated 

 branch of the fifth, and not to the portio dura. 



Beyond this its junction with the fifth, it is 

 no longer possible to trace any special nerve, 

 or to indicate its subdivisions by names, since, 

 on the masseter, a succession of diverging 

 branches are given off from it, each of which, 

 by uniting with its neighbours above and 

 below, and giving off fresh ramifications from 

 the branches of union, forms part of a com- 

 plicated network, in which the original con- 



stituent branches, and the respective shares 

 which they take in the new loops, can scarcely 

 be recognized. Cruveilhier and Bonamy have 

 traced this looped arrangement still more 

 minutely, having followed it into the smallest 

 branches of the nerve, and especially into 

 those which supply the orbicularis ; and it 

 has been likened *by them to the mode in 

 which the mesenteric arteries break up to 

 reach the intestine. 



Notwithstanding this free communication, 

 however, the different portions of this re- 

 ticulated arrangement may be conveniently 

 regarded in succession, in order the better to 

 appreciate their distribution. 



Superiorly are the temporal branches ; these 

 emerge from beneath the upper border of the 

 parotid, and cross the zygoma to be distri- 

 buted to the superficial muscles of the auricle, 

 the attollens and attrahens aurem, and to 

 the anterior belly of the occipito-frontalis 

 beyond these. The orbital branch of the 

 second division of the fifth joins, by its long 

 ascending filaments, with these branches of 

 the facial; so also a perforating filament from 

 the deep temporal of the third division, with 

 others from the auriculo-temporal of the same 

 portion of the fifth, are usually traceable to 

 an union with this nerve. 



Anteriorly to these are the numerous or- 

 bicular or supra-orbital branches. They pass 

 obliquely forwards and upwards over the 

 malar bone, to supply the orbicularis palpe- 

 brarum, and corrugator supercilii muscles. 

 Their connection with the fifth occurs chiefly 

 by the supra-orbital and lachrymal of the oph- 

 thalmic division ; but others join the malar 

 branch of the second division, where it emerges 

 from its foramen in the malar bone near the 

 outer angle of the orbit. 



The infra-orbital filaments pass almost hori- 

 zontally forwards from the temporo-facial divi- 

 sion towards the side of the nose. In this 

 course, accompanied by the parotid duct, they 

 cross over the masseter muscle; and more 

 anteriorly, they pass beneath the different 

 muscles which descend to the angle of the 

 mouth and upper lip, and are distributed to 

 them by numerous filaments which enter their 

 deep surface. In this manner the greater 

 and lesser zygomatic, with the proper and 

 common elevator of the lip, and the elevator 

 of the angle of the mouth, receive their ner- 

 vous supply ; and the pyramidalis and trans- 

 versalis nasi also obtain filaments from this 

 part of the facial. Many of these, in passing 

 forwards, unite at right angles with the ra- 

 diating bundles of filaments into which the 

 infra-orbital nerve divides after leaving the 

 foramen of the same name. Besides this 

 union with the second division of the fifth, 

 it unites with the ophthalmic by a small twig 

 of its nasal branch, which appears between 

 the lateral cartilage and the nasal bone, and 

 generally by an infra-trochlear filament of the 

 same portion in the angle of the eye. 



Tlnebuccal branches, with the same direction 

 as the preceding, occupy a position at a some- 

 what lower level on the face, in the neigh- 

 N \ 2 



