1218 A MANUAL OF ANATOMY 



sensory roots. Many of their fibres, however, pass clear of the grey 

 matter of the ganglion, and are prolonged into the nasal and de- 

 scending palatine branches of the ganglion. 



The posterior superior dental nerve arises from the superior 

 maxillary as it is about to pass through the spheno-maxillary 

 fissure, and soon divides into two branches, which sometimes 

 arise separately. They descend in grooves on the zygomatic 

 surface of the superior maxilla, in company with branches of the 

 posterior dental artery, and give off branches to the gum and con- 

 tiguous part of the mucous membrane of the cheek. Thereafter 

 they traverse the posterior dental canals, and within the substance 

 of the bone they communicate with each other and with the middle 

 superior dental nerve to form a delicate plexus, from which branches 

 are given off to the pulps of the three upper molar teeth. Slender 

 filaments are also furnished to the mucous membrane lining the 

 antrum of Highmore. 



The middle superior dental nerve arises from the main trunk as 

 it lies in the infra-orbital groove near the spheno-maxillary fissure. 

 It descends, in company with the middle dental artery, in the middle 

 dental canal of the superior maxilla. Its branches communicate 

 with each other, and with the posterior superior and anterior 

 superior dental nerves within the substance of the bone, to form a 

 delicate plexus, from which branches are given to the pulps of 

 the upper two bicuspid teeth and to the gum. This nerve also 

 furnishes delicate filaments to the mucous membrane lining the 

 antrum of Highmore. Two enlargements are described in connec- 

 tion with the middle superior dental nerve. One is situated at its 

 communication with the posterior superior dental nerve, and is 

 known as the ganglion of Valentin ; and the other at its communi- 

 cation with the anterior superior dental, this one being known as 

 the ganglion of Bochdalek. 



The anterior superior dental nerve arises from the infra-orbital 

 nerve near the front part of the infra-orbital canal, and descends, 

 in company with the anterior dental artery, in the anterior dental 

 canal. Its branches communicate with each other and with the 

 middle superior dental nerve to form a delicate plexus, from which 

 branches are given to the pulps of the upper canine and incisor 

 teeth. This nerve also furnishes delicate filaments to the mucous 

 membrane lining the antrum of Highmore, and a nasal branch, 

 which enters the nasal fossa and supplies the mucous membrane of 

 the anterior part of the inferior meatus and adjacent portion of 

 the inferior concha. 



The facial branches of the infra-orbital nerve, namely, inferior 

 palpebral, lateral nasal, and superior labial, have been already 

 described, see p. 1177. 



It is to be noted that there are three superior dental nerves, 

 right and left, the posterior being a branch of the superior maxillary, 

 and the middle and anterior being branches of the infra-orbital ; 

 whilst there is only one inferior dental nerve, which is a branch of 

 the inferior maxillary. 



