990 



THE NERVE SYSTEM 



The Inferior Maxillary or Mandibular Nerve (n. mandibularis) (Figs. 733 

 and 734). The inferior maxillary or third division of the trigeminal nerve dis- 

 tributes branches to the teeth and gums of the mandible, the integument of the 

 temple and external ear, the lower part of the face and lower lip, and the muscles 

 of mastication; it also supplies the tongue with a large branch. It is the largest 

 of the three divisions of the trigeminal, and is made up of two roots a large or 

 sensor root, proceeding from the inferior angle of the Gasserian ganglion; and a 

 small or motor root, which passes beneath the ganglion and unites with the sensor 

 root just after its exit from the skull through the foramen ovale (Figs. 731 and 734). 

 Immediately beneath the base of the skull this nerve divides into two trunks^ 

 anterior and posterior. Previous to its division the primary trunk gives off from 

 its inner side a recurrent (meningeal) branch and the nerve to the Internal ptery- 

 goid muscle. 



The Recurrent or Meningeal Branch (n. spinosus) is given off directly after its exit 

 from the foramen ovale. It passes backward into the skull through the foramen 

 spinosum with the middle meningeal artery. It divides into two branches, anterior 

 and posterior, which accompany the main divisions of the artery and supply the 

 dura. The posterior branch also supplies the mucous lining of the mastoid cells. 

 The anterior branch communicates with the dural branch of the superior maxillary 

 nerve. 



The Internal Pterygoid Nerve (w. pterygoideus inter nus), given off from the 

 inferior maxillary previous to its division, is intimately connected at its origin 

 with the otic ganglion. It is a long and slender branch, which passes inward to 

 enter the deep surface of the Internal pterygoid muscle. 



The anterior and smaller division of the inferior maxillary nerve, which receives 

 nearly the whole of the motor root of the trigeminal nerve, divides into branches 

 which supply the muscles of mastication. They are the masseteric, deep temporal, 

 buccal, and external pterygoid branches (Fig. 734). 



The masseteric branch (n. massetericus) passes outward, above the External 

 pterygoid muscle, in front of the temporomandibular articulation and behind 

 the tendon of the Temporal muscle; it crosses the sigmoid notch with the masse- 

 teric artery, to the deep surface of the Masseter muscle, in which it ramifies 

 nearly as far as its anterior border. It gives a filament to the temporoman- 

 dibular joint. 



The deep temporal branches (nn. temporales profundi), two in number, anterior 

 and posterior, supply the deep surface of the Temporal muscle. The posterior 

 branch (n. temporalis profundus posterior), of small size, is placed at the back of 

 the temporal fossa. It sometimes arises in common with the masseteric branch. 

 The anterior branch (n. temporalis profundus anterior) is frequently given off with 

 the buccal nerve; it is reflected upward, at the pterygoid ridge of the sphenoid, 

 to the front of the temporal fossa. Frequently a third branch (middle deep tem- 

 poral) is present. 



The buccal or buccinator branch (n. buccinatorius) passes forward between the 

 two heads of the External pterygoid; and downward beneath or through the fibres 

 of the Temporal muscle; it gives a branch to the External pterygoid during its 

 passage through that muscle, and a few ascending filaments to the Temporal 

 muscle, one of which occasionally joins with the anterior branch of the deep tem- 

 poral nerve. The superior or upper branch supplies the integument and upper 

 part of the Buccinator muscle, joining with the facial nerve around the facial 

 vein. The inferior or lower branch passes forward to .the angle of the mouth; 

 it supplies the integument and Buccinator muscle, as well as the mucous membrane 

 lining the inner surface of that muscle, and joins the facial nerve. 1 



'There seems to be no reason to doubt that the branch supplying the Buccinator muscle is entirely a nerve of 

 ordinary sensation, and that the true motor supply of this muscle is from the facial. 



