254 THE CRANIAL NERVES. 



part at least continuous with the portio intermedia, leaves the facial nerve at the 

 lower end of the aqueduct of Fallopius, and is directed upwards and forwards 

 through a small canal (iter chorda posterius) which opens on the posterior wall of 

 the tympanum, close to the attachment of the tympanic membrane. It then arches 

 forwards, being invested by the mucous lining of the cavity, across the upper part 

 of the membrane and over the inner side of the handle of the malleus, above the 

 insertion of the tensor tympani muscle. Finally, leaving the cavity by an aperture 

 (Her chordce anterius] at the inner end of the Glaserian fissure, the nerve inclines 

 downwards on the mesial side of the internal lateral ligament of the jaw, and unites 

 at an acute angle with the lingual nerve, in which its fibres are continued to the 

 submaxillary ganglion and the tongue. Before joining the lingual nerve, the chorda 

 receives a communicating filament from the otic ganglion. 



A communication with the auricular branch of the pneumo-gastric 

 nerve is generally present, in the form of a twig leaving the facial nerve close 

 above the stylo-mastoid foramen (see p. 265). 



B. Arising from the facial nerve below the base of the skull. 



The posterior auricular nerve arises close to the stylo-mastoid foramen, and 

 turns upwards between the ear and the mastoid process, where it divides into 

 auricular and occipital branches. 



The auricular branch ascends behind the ear and is distributed to the retrahens 

 auriculam and the small muscles on the cranial surface of the pinna. A twig is 

 sometimes continued upwards to the attollens muscle. 



The occipital branch is directed backwards close to the bone, and supplies the 

 posterior part of the occipito-frontalis muscle. 



The posterior auricular nerve receives communications from the great auricular 

 and small occipital nerves of the cervical plexus, as well as from the auricular branch 

 of the pneumo-gastric, and certain filaments which may sometimes be followed 

 from its branches to the skin are probably composed of fibres derived from these 

 nerves. 



The digastric branch arises close below the preceding nerve, and divides into 

 two or three filaments which enter the posterior belly of the digastric muscle ; one 

 of these sometimes passes through or above the digastric, and joins the glosso 

 pharyngeal nerve near the base of the skull. 



The stylo-hyoid branch, long and slender, arises in common with thewiigastric 

 branch, and inclines forwards to enter the stylo-hyoid muscle on its posterior aspect. 



TEMPORO-FACIAL DIVISION. The temporo-facial, the larger of the two primary 

 divisions of the facial nerve, is directed forwards through the upper part of the 

 parotid gland, crossing over the external carotid artery and the temporo-maxillary 

 vein. It receives one or two considerable offsets from the auriculo-temporal nerve 

 (p. 246), and speedily divides into a number of branches which form, by their com- 

 munications with one another and with branches of the fifth nerve, a network over 

 the side of the face, extending as high as the temple and as low as the mouth. Its 

 ramifications are arranged in temporal, malar, and infraorbital sets. 



The temporal branches ascend over the zygoma and supply the attrahens and 

 attollens auriculam muscles, the frontalis, the upper part of the orbicularis palpe- 

 brarum, and the corrugator supercilii. One or two filaments pass to the auricle, and 

 are distributed to the small muscles on its outer surface. These branches form 

 communications with the auriculo-temporal nerve, the temporal branch of the 

 superior maxillary, and the supraorbital and lachrymal branches of the ophthalmic 

 nerve. 



The malar branches cross the malar bone to reach the outer side of the orbit 

 and supply the orbicular muscle. Some filaments are distributed to both the upper 



