246 THE CRANIAL NERVES. 



enters at the hinder part of its deep surface. It also gives a filament or two to the 

 articulation of the jaw. 



The external pterygoid nerve generally arises in common with the buccal 

 branch, and penetrates the inner surface of its muscle. 



The buccal nerve, which differs from the foregoing branches in being entirely 

 a sensory nerve, is usually conjoined at its origin with the anterior deep temporal 

 and the external pterygoid nerves. It passes forwards between the heads of the 

 external pterygoid, and then descends in close contact with the inner side (occa- 

 sionally perforating some of the fibres) of the temporal muscle at its insertion, to 

 the surface of the buccinator muscle. Here it divides into several branches which 

 join in a plexus round the facial vein with the buccal branches of the facial nerve, 

 and are finally distributed to the skin and mucous membrane of the cheek, extend- 

 ing as far forwards as the angle of the mouth. 



Varieties. The buccal nerve is occasionally replaced by a branch of the superior 

 maxillary (p. 240). It has been seen by Turner arising from the inferior dental nerve in the 

 dental canal, and issuing by a small foramen in the alveolar border of the lower jaw, close to 

 the ramus. Gaillet describes it in one case as arising directly from the Gasserian ganglion, 

 and passing from the cranium through a special aperture between the round and oval 

 foramina. 



The internal pterygoid nerve (fig. 164, 13) is closely connected at its origin 

 with the otic ganglion, and descends to the inner or deep surface of its muscle, 

 being separated from the lingual and inferior dental nerves by the pterygo-spinous 

 ligament when that band is present (see Osteology, p. 47). From this nerve mainly, 

 as it passes the otic ganglion, arise the small branches to the tensor palati and tensor 

 tympani muscles. 



Auricula-temporal nerve. The auriculo-temporal nerve takes its origin close 

 to the foramen ovale, usually by two roots which embrace the middle meningeal 

 artery. It is directed at first backwards, beneath the external pterygoid muscle, to 

 the inner side of the neck of the lower jaw ; then changing its course, it turns up- 

 wards between the ear and the temporo-maxillary articulation, under cover of the 

 upper end of the parotid gland ; and finally, emerging from beneath the latter, it 

 ascends over the base of the zygoma in company with the superficial temporal artery, 

 behind which it is placed, to terminate on the side of the head as the superficial 

 temporal nerve. 



Branches. (a) Communicating branches. The roots of the auriculo-temporal 

 nerve are joined, close to their origin, by slender filaments from the otic ganglion ; 

 and from the trunk of the nerve, as it turns upwards, one or two considerable 

 branches are sent forwards round the commencement of the superficial temporal 

 artery to the temporo-facial division of the facial nerve. 



(&) The articular branches are one or two fine twigs to the hinder part of the 

 temporo-maxillary articulation. 



(c) The nerves of the external auditory meatus are two in number, upper and 

 lower, and enter the canal between the osseous and cartilaginous parts of its wall. 

 They supply the skin of the meatus, and the upper one sends a filament to the 

 membrana tympani. 



(d) Parotid branches pass from the nerve, or from its connecting branches with 

 the facial, to the gland. 



(e) The anterior auricular nerves are usually two in number, and supply the skin 

 of the tragus and of the upper and fore part of the pinna. 



(/) The superficial temporal nerve divides into slender branches which supply 

 the skin over the greater part of the temporal region, the anterior ones forming 

 communications with the temporal branches of the facial nerve (fig. 171, 18). 



