1242 HUMAN ANATOMY. 



a. The posterior superior nasal nerve (rr. laterales) supplies the mucous membrane of the 

 posterior superior portion of the outer wall of the nasal fossa. 



b. The naso-palatine nerve (n. nasopalatinus) (Fig. 1059) crosses the roof of the nasa! 

 chamber and passes downward and forward in a groove in the vomer and septal cartilage to 

 reach the anterior palatine canal. It then passes through the foramen of Scarpa, the left nerve 

 through the anterior and the right one through the posterior canal, the two nerves forming in 

 this situation a fine plexus. Having reached the inferior surface of the hard palate, the naso- 

 palatine inosculates with the large posterior palatine nerve. It supplies the roof and septum of 

 the nose and that portion of the hard palate which lies posterior to the incisor teeth. 



4. The posterior branch (Fig. 1059) also known as the pharyngeal or 

 ptery go -palatine, leaves the spheno-maxillary fossa through the pterygo-palatine 

 canal and supplies the mucous membrane of the naso-pharynx in the region of the 

 fossa of Rosenmiiller. 



Variations. — Branches of the ganglion have been described as passing to the abducent 

 nerve, to the ciliary ganglion and to the optic nerve or its sheath. The accessory posterior 

 palatine nerve is sometimes absent. Quite frequently the left naso-palatine nerve passes 

 through the posterior foramen of Scarpa and the right nerve through the anterior. 



III. The Mandibular Nerve. — The mandibular or inferior maxillary branch 

 (n. mandibularis) of the trigeminal nerve is the largest of its three divisions and, being a 

 mixed nerve, consists of two portions, one sensory and the other motor. "Wvo. sensory 

 part is the larger and arises from the lower anterior portion of the Gasserian ganglion. 

 The smaller motor part is the motor root of the trigeminal ner\-e, which contributes 

 exclusively to this division of the fifth nerve. Although these two portions are inti- 

 mately associated in their passage through the foramen ovale, the motor bundle 

 lying to the median side of the sensory, it is not until they emerge from the skull 

 that they unite, immediately below the lower margin of the foramen ovale, to form 

 the mandibular nerve. The sensory portion supplies the skin of the side of the 

 head, the auricle of the ear, the external auditory meatus, the lower portion of the 

 face and the lower lip, the mucous membrane of the mouth, tongue and mastoid 

 cells, and the lower teeth and gums, the salivary glands, the temporo-mandibular 

 articulation, the dura mater and the skull. The motor portion supplies the muscles 

 of mastication (the temporal, the masseter and the external and internal pterygoids), 

 the anterior belly of the digastric, the mylo-hyoid, the tensor palati and the tensor 

 tympani muscles. By union of the two constituents, a thick common trunk is formed, 

 which, after a course of from 2-3 mm., separates under cover of the external ptery- 

 goid muscle into an a^iterior ds\A 2. posterior division (Fig. 1063). 



Branches and Distribution. — The branches from the main trunk of the 

 mandibular nerve are: (i) the recurrent branch and (2) the interyial pterygoid 7ierve. 



1. The recurrent branch (n. spinosus) arises just beneath the foramen ovale 

 and accompanies the middle meningeal artery into the cranium through the foramen 

 spinosum. It then divides into two branches, the anterior of which supplies the greater 

 wing of the sphenoid and the adjacent dura mater, while the posterior passes through 

 the petro-squamous suture and supplies the mucous membrane of the mastoid 

 air-cells. 



2. The internal pterygoid nerve (n. pterygoideus internus) (Fig. 1059) 

 passes downward on the mesial side of its muscle and, in addition to supplying the 

 pterygoid muscle, gives of^ the motor root of the otic ganglion and filaments to the 

 tensor tympani and tensor palati muscles. 



The Anterior Division of the mandibular nerve (n. masticatorius) is motor, 

 with the exception of its buccal branch, and receives almost the entire motor constit- 

 uent of the trigeminal. It passes downward and forward for a short distance under 

 the external pterygoid muscle and then breaks up into its branches. 



Branches. — These are: (i) the masseteric, (2) the external pterygoid , (3) 

 \\\^ deep temporal ■ajciA (4) Xh^ buccal nerve. 



I. The masseteric nerve (n. massetericus) (Fig. 1063) passes over the 

 upper border of the external pterygoid and behind the posterior margin of the 

 temporal muscle. It takes a course horizontally outward and traverses the sigmoid 



