778 THE NEKVOUS SYSTEM. 



The branches from the ganglion are seven in number. 



(a) The pharyngeal branch passes backwards through the pharyngeal canal to 

 supply the mucous membrane of the roof of the pharynx. 



(&) Nervi Palatini. The palatine nerves, three in number, are directed down- 

 wards to the palate through the palatine canals. 



The large anterior palatine nerve emerges on the under surface of the palate 

 through the greater palatine foramen, and at once separates into numerous branches 

 for the supply of the mucous membrane of the soft and the hard palate. Its 

 anterior filaments communicate with branches of the naso-palatine nerve. The 

 main nerve gives off, as it lies in the palatine canal, a small posterior inferior lateral 

 nasal nerve (rami nasales posteriores inferiores laterales), which enters the nasal 

 cavity and supplies the mucous membrane of the lower part of its lateral wall. 



The middle palatine nerve descends through a small palatine canal, and, piercing the 

 pyramidal process of the palate bone, is distributed to the mucous membrane of the 

 soft palate, uvula, and palatine tonsil. It possibly conveys motor fibres to the levator 

 veli palatini and uvular muscles. The n. palatinus posterior (posterior palatine 

 nerve) consists of one or more small twigs which pass through lesser palatine canals, 

 and supply branches to the mucous membrane of the tonsil, soft palate, and uvula. 



(c) The branches directed medially from the spheno-palatine ganglion enter the 

 nasal cavity through the spheno-palatine foramen. They are two in number the 

 posterior superior lateral nasal and the naso-palatine. The posterior superior 

 lateral nasal branch (rami nasales posteriores superiores laterales) is a small nerve 

 destined for the mucous membrane of the superior and posterior part of the lateral 

 wall of the nasal cavity. The n. nasopalatinus (naso-palatine nerve), after passing 

 through the spheno-palatine foramen, crosses the roof of the nasal cavity, and 

 extends obliquely downwards and forwards along the nasal septum, grooving the 

 vomer in its course, to reach the incisive foramen near the front of the hard palate. 

 The nerves pass through the subordinate median foramina (of Scarpa), the lefb 

 nerve in front of the right. In the incisive foramen the two nerves communicate 

 together. They then turn backwards and supply the mucous membrane of the 

 hard palate. They communicate posteriorly with terminal filaments of the anterior 

 palatine nerves. In its course through the nasal cavity the naso-palatine nerve 

 furnishes collateral branches to the mucous membrane of the roof and septum of 

 the nose (posterior superior medial branches') (Fig. 649, p. 774). 



(d) Rami Orbitales. The orbital branches, one or more minute branches, pass 

 upwards to the periosteum of the orbit from the spheno-palatine ganglion. 



NERVUS MANDIBULARIS. 



The mandibular nerve is formed by the union of two roots ; a large sensory 

 root, from the semilunar ganglion, and the small motor root of the trigeminal 

 nerve, which is wholly incorporated with the mandibular trunk. The two roots 

 pass together in the dura mater of the middle fossa of the base of the skull 

 to the foramen ovale, through which they emerge into the infra-temporal fossa. 

 Outside the skull they combine to form a single trunk, which soon separates into 

 anterior and posterior divisions. 



At its emergence from the skull the nerve is deeply placed beneath the middle 

 of the zygoinatic arch, and is concealed by the ramus of the mandible, and by the 

 masseter, temporal, and external pterygoid muscles. 



The branches of the nerve may be divided into two series (1) those derived 

 from the undivided nerve, and (2) those derived from its terminal divisions. 



The branches of the undivided nerve are two in number, (a) A small nervus 

 spinosus (O.T. recurrent nerve) arises just outside the skull, and accompanying the 

 middle meningeal artery through the foramen spinosum, supplies the dura mater. 

 (6) In the infra-temporal region a small branch arises for the supply of the internal 

 pterygoid muscle. This nerve forms a connexion with the otic ganglion. 



The terminal divisions of the nerve are a small anterior and a large posterior 

 trunk. 



The small anterior trunk (nervus masticatorius or masticator nerve) passes 



