c40 THE CRANIAL NERVES. 



nerve, and three or four in number, are continued downwards beneath the proper 

 elevator of the tipper lip. Ramifying as they descend, these nerves are distri- 

 buted to the integument, the mucous membrane of the mouth, the labial glands, 

 and the muscles of the upper lip. 



Near the orbit the infraorbital branches of the superior maxillary 

 nerve are joined by considerable branches of the facial nerve, the union 

 between the two being named infraorhiial j)lcxus. 



Spheno- Palatine Ganglion. 



The spheno-palatine ganglion, frequently named JMeckel's or the nasal 

 ganglion, is dee])ly placed in the spheno-maxillary fossa, close to the 

 spheno-palatine foramen. It receives the two spheno-palatine branches 

 which descend together fi'om tlie superior maxillary nerve as it crosses the 

 top of the fossa. It is of greyish colour, triangular in form, and convex 

 on the outer surface. Its diameter is about the fifth of an inch. The 

 grey or ganglionic substance does not involve all the fibres of the 

 spheno-palatine branches of the upper maxillary nerve, ])ut is placed at 

 the back part, at the point of junction of the sympathetic or deep 

 branch of the Vidian, so that the spheno-palatine nerves proceeding to 

 the nose and palate pass to their destination without being incorporated 

 with the ganglionic mass. 



Branches proceed from the ganglion upwards to the oi-ljit, downwards 

 to the palate, inwards to the nose, and backwards through the Vidian 

 and pterygo-palatine canals. 



AscEXDixG BRANCHES. — Thcsc cousist of three or more very small 

 twigs, which reach the orbit l^y the spheno-maxillary fissure, and are 

 distributed to the periosteum. 



Bock describes a branch ascending from the ganglion to the sixth nerve ; Tiede- 

 manu. one to the lower angle of the ophthalmic ganglion. The filaments described 

 by Hirzel as ascending to the optic nerve, most probably join the ciliary twigs 

 which surround that nerve. 



Descending branches. — These are three in number, — the large, 

 the small, and the external palatine nerves, and are continued chiefly 

 from the spheno-})alatine branches of the superior maxillary. They are 

 distributed to the tonsil, the hard and soft palate, the gums, and the 

 mucous membrane of the nose. 



a. The lavr/cr or anto-ior ixilatlne nerve descends in the palato-maxillary canal, 

 and divides in the roof of the mouth into branches, which are received into 

 grooves in the hard palate, and extend forwards nearly to the incisor teeth. In 

 the mouth it supplies the gums, the glands, and the mucous membrane of 

 the hard palate, and joins in front with the naso-palatine nerve. AMien enter- 

 ing its canal, this palatine nerve gives a nasal branch which ramifies on the 

 middle and lower spongy bones ; and a little before leaving the canal, another 

 branch is supplied to the membrane covermg the lower spongy bone : these are 

 'inferior nasal hranrhc^: Opposite the lower spongy bone springs a small branch, 

 which is continued to the soft palate in a separate canal behind the trunk of 

 the nerve. 



h. The smaller or j>oxferior j'alattne Ijranch. arising near the preceding nerve, 

 enters with a small artery the lesser palatine canal, and is conducted to the soft 

 palate, the tonsil, and the uvula. According to Meckel, it supplies the levator 

 palati muscle. 



e. The c,rfcr)ial juilaf'nie nerve, the smallest of the series, courses between the 

 upper maxilla and the external pterygoid muscle, and enters the external i^alatine 

 canal between the maxillary bone and the pter\-goid process of the palate bone. 

 At its exit from the canal it gives inwards a l^ranch to the uvula, and outwards 

 another to the tonsil and palate. Occasionally this nerve is altogether wanting. 



