THE HEAD AND NECK 1207 



(i) the intraparotid lymphatic glands, and {2) the superior deep 

 cervical glands. 



Inferior Maxillary Nerve. — This is the third division of the fifth 

 nerve. It is a mixed nerve, and consists of two roots — sensor^' and 

 motor. The sensory root, which is of large size, arises from the 

 Gasserian ganglion, and the motor root represents the entire motor 

 root of the fifth nerve. Both roots leave the cranial cavity through 

 the foramen ovale, and immediately after their exit they unite 

 to form a mixed nerve, that is to say, a nerve composed of both 

 sensory and motor fibres. This nerve is very short, and lies deeply 

 in the zygomatic fossa, under cover of the external pterygoid 

 muscle, where it gives off two branches, namely, a recurrent branch, 

 and the internal pterygoid nerve. Thereafter it immediately 

 breaks up into two parts, known as the anterior and posterior 

 divisions. The recurrent branch enters the cranial cavity through 

 the foramen spinosum, along with the middle meningeal artery, 

 and divides into two branches — anterior and posterior. The 

 anterior branch is distributed to the adjacent dura mater, and the 

 posterior branch passes through the fissure between the petrous 

 and squamous parts of the temporal bone, to be distributed to the 

 mucous lining of the mastoid cells. The internal pterygoid nerve 

 arises from the deep surface of the undivided inferior maxillary 

 nerve, and passes downwards to enter the deep surface of the 

 internal pterygoid muscle. Close to its origin it is intimately 

 related to the otic ganglion. 



Anterior Division of the Inferior Maxillary Nerve. — This division 

 is smaller than the posterior, and is principally motor in function, 

 the only sensory branch furnished by it being the long buccal nerve. 

 Its branches are as follows: (i) masseteric, furnishing the posterior 

 deep temporal; (2) middle deep temporal; and (3) long buccal, giving 

 off the external pterygoid and anterior deep temporal, after which 

 it is purely sensory. 



The masseteric nerve passes upwards beneath the upper head of 

 the external pterygoid muscle, where it furnishes the posterior deep 

 temporal nerve. It then passes outwards over the upper border of 

 the external pterygoid, and over the sigmoid notch of the lower jaw, 

 behind the temporal muscle, to enter the upper part of the masseter 

 on its deep surface. 



The deep temporal nerves are three in number — anterior, middle, 

 and posterior. The antertor deep temporal nerve usually arises from 

 the long buccal after it has emerged between the two heads of the 

 extemcd pterj'goid. It passes upwards, superficial to the upper 

 head of that muscle, and enters the anterior part of the temporal 

 muscle on its deep surface. The middle deep temporal nerve is a 

 direct branch of the anterior division of the inferior maxL[lar\', and 

 it ascends beneath the external pterygoid to enter the middle part 

 of the temporal muscle on its deep surface. The posterior deep 

 temporal nerve springs from the masseteric nerve beneath the 



