

THE ACOUSTIC NERVE 905 



the majority of its fibers are afferent, and are continued onward through the mus- 

 cular substance of the tongue to the mucous membrane covering its anterior 

 two-thirds; they constitute the nerve of taste for this portion of the tongue. Before 

 uniting with the lingual nerve the chorda tympani is joined by a small branch from 

 the otic ganglion. 



The Posterior Auricular Nerve (n. auricularis posterior) arises close to the stylo- 

 mastoid foramen, and runs upward in front of the mastoid process; here it is joined 

 by a filament from the auricular branch of the vagus, and communicates with the 

 posterior branch of the great auricular, and with the lesser occipital. As it ascends 

 between the external acoustic meatus and mastoid process it divides into auricular 

 and occipital branches. The auricular branch supplies the Auricularis posterior 

 and the intrinsic muscles on the cranial surface of the auricula. The occipital 

 branch, the larger, passes backward along the superior nuchal line of the occipital 

 bone, and supplies the Occipitalis. 



The Digastric Branch (ram us digastricus) arises close to the stylomastoid foramen, 

 and divides into several filaments, which supply the posterior belly of the Digas- 

 tricus; one of these filaments joins the glossopharyngeal nerve. 



The Stylohyoid Branch (ramus stylohyoideus) frequently arises in conjunction 

 with the digastric branch ; it is long and slender, and enters the Stylohyoideus about 

 its middle. 



The Temporal Branches (rami temporales) cross the zygomatic arch to the temporal 

 region, supplying the Auriculares anterior and superior, and joining with the zygo- 

 maticotemporal branch of the maxillary, and with the auriculotemporal branch 

 of the mandibular. The more anterior branches supply the Frontalis, the Orbicu- 

 laris oculi, and the Corrugator, and join the supraorbital and lacrimal branches 

 of the ophthalmic. 



The Zygomatic Branches (rami zygomatici; malar branches) run across the zygo- 

 matic bone to the lateral angle of the orbit, where they supply the Orbicularis oculi, 

 and join with filaments from the lacrimal nerve and the zygomaticofacial branch 

 of the maxillary nerve. 



The Buccal Branches (rami buccales; infraorbital branches'), of larger size than the 

 rest, pass horizontally forward to be distributed below the orbit and around the 

 mouth. The superficial branches run beneath the skin and above the superficial 

 muscles of the face, which they supply: some are distributed to the Procerus, 

 joining at the medial angle of the orbit with the infratrochlear and nasociliary 

 branches of the ophthalmic. The deep branches pass beneath the Zygomaticus and 

 the Quadratus labii superioris, supplying them and forming an infraorbital plexus with 

 the infraorbital branch of the maxillary nerve. These branches also supply the 

 small muscles of the nose. The lower deep branches supply the Buccinator and 

 Orbicularis oris, and join with filaments of the buccinator branch of the mandibular 

 nerve. 



The Mandibular Branch (ramus marginalis mandibulce) passes forward beneath 

 the Platysma and Triangularis, supplying the muscles of the lower lip and chin, 

 and communicating with the mental branch of the inferior alveolar nerve. 



The Cervical Branch (ramus colli} runs forward beneath the Platysma, and forms 

 a series of arches across the side of the neck over the suprahyoid region. One 

 branch descends to join the cervical cutaneous nerve from the cervical plexus; 

 others supply the Platysma. 



THE ACOUSTIC NERVE (EIGHTH NERVE). 



The acoustic nerve consists of two distinct sets of fibers which differ in their 

 peripheral endings, central connections, functions, and time of medullation. It is 

 soft in texture and devoid of neurilemma. 



