TEE CRANIAL OE ENCEPHALIC NERVES. 725 



anterior wall in describing a curve downwards, and passes among the 

 chain of auditory bones, between the handle of the malleus and long branch 

 of the incus. Escaping from the middle ear by a canal (fissura Glaseri) on the 

 limits of the mastoid and petrous portions of the temporal bone, it proceeds 

 forwards and downwards, and finally joins the gustatory nerve aftet a short 

 course beneath the external pterygoid muscle, outside the guttural pouch. 



5. ANASTOMOSING BRANCH OF THE PNEUMOGASTRIC NERVE. (See the 

 description of the tenth pair.) 



6. OCCIPITO-STYLOID NERVE. (Fig. 336, 3.) 



7. STYLO-HYOID NERVE. 



8. DIGASTRIC NERVE (Fig. 336, 4). These three spring from a 

 common fasciculus at the stylo-mastoid foramen, and ramify in their 

 respective muscles, after a certain course beneath the parotid gland. 



9. CERVICAL BRANCH (Figs. 336, 6). This nerve has its origin almost 

 in the middle of the subparotideal portion of the facial, near a particular loop 

 thrown by that nerve around the posterior auricular artery, and often from 

 this loop itself. 



It afterwards traverses the parotid gland from within to without, and 

 above to below, to descend at first on its external face, beneath the parotido- 

 auricularis muscle, then into the jugular channel, where it is lodged below the 

 deep face, or in the substance of the subcutaneous muscle of the flfeck, which 

 receives its terminal divisions near the anterior appendix of the sternum. 



In its course this nerve communicates with the inferior branches of the 

 second, third, fourth, fifth, and sixth cervical pairs by branches from them ; 

 it sends numerous collateral filaments into the texture of the subcutaneous 

 muscle. 



10. FILAMENTS OF THE GUTTURAL POUCH AND PAROTID GLAND. 

 Remarkable for their number and tenuity, these filaments do not otherwise 

 deserve particular mention. 



11. POSTERIOR AURICULAR NERVE (Fig. 336, 2). It commences at 

 the stylo-mastoid foramen, is directed upwards beneath the parotid gland, 

 accompanying the posterior auricular artery, and is distributed to the 

 posterior muscles of the external ear. It sometimes offers at its origin a 

 loop analogous to that embracing the posterior auricular artery. 



12. MIDDLE AURICULAR NERVE. Most frequently this arise from the 

 same point as the preceding nerve it might be said in common with it 

 ascends towards the base of the concha in traversing the parotid gland, and 

 pierces the cartilage to supply the interconchal integument and the con- 

 tractile fibres which cover its adherent face in some parts. 



13. ANTERIOR AURICULAR NERVE (Fig. 336, 5). This is the largest 

 of the three auricular nerves. After being detached from the facial nerve, 

 opposite the cervical branch, and after ascending across the parotideal 

 tissue, it gains the external face of the zygomatic process, where it meets 

 the superficial divisions of the lachrymal nerve; it continues forward 

 beneath the external parieto-auricular muscle, reaches the base of the orbital 

 process at the supra-orbital foramen, there crossing the terminal branches of 

 the nerve of that name ; it then descends vertically within the orbit to below 

 the nasal angle of the eye, where it mixes with the superficial divisions of 

 the palpebro -nasal nerve, and finally terminates on the face in the lachrymal 

 and supernaso-labialis muscles. 



In its progress, it gives off numerous ramuscules to the anterior 

 muscles of the ear, the fronto- supra-orbital, and the orbicularis of the eye- 

 lids, whose contractibility it excites. 

 49 



