THE TRIGEMINAL NERVE 



891 



of the maxilla, and, passing from behind forward in the substance of the bone, 

 communicate with the middle superior alveolar nerve, and give off branches to the 

 lining membrane of the maxillary sinus and three twigs to each molar tooth; these 

 twigs enter the foramina at the apices of the roots of the teeth. 



The Middle Superior Alveolar Branch (ramus alveolaris superior medius; middle 

 superior dental branch), is given off from the nerve in the posterior part of the infra- 

 orbital canal, and runs downward and forward in a canal in the lateral wall of the 

 maxillary sinus to supply the two premolar teeth. It forms a superior dental plexus 

 with the anterior and posterior superior alveolar branches. 



The Anterior Superior Alveolar Branch (ramus alveolaris superior anteriores; ante- 

 rior superior dental branch), of considerable size, is given off from the nerve just 

 before its exit from the infraorbital foramen; it descends in a canal in the anterior 

 wall of the maxillary sinus, and divides into branches which supply the incisor 

 and canine teeth. It communicates with the middle superior alveolar branch, 

 and gives off a nasal branch, which passes through a minute canal in the lateral wall 

 of the inferior meatus, and supplies the mucous membrane of the anterior part of 

 the inferior meatus and the floor of the nasal cavity, communicating with the nasal 

 branches from the sphenopalatine ganglion. 



MAXILLARY 

 I 



POSTERIOR 

 DENTAL 



ORBITAL 



BRANCH OUT 



SPHENOPALATINE 



SUPERIOR CERVICAL 

 GANGLION OF THE 



SYMPATHETIC 



FIG. 779. Alveolar branches of superior maxillary nerve and sphenopalatine ganglion. (Testut.) 



The Inferior Palpebral Branches (rami palpebrales inferiores; palpebral branches) 

 ascend behind the Orbicularis oculi. They supply the skin and conjunctiva of the 

 lower eyelid, joining at the lateral angle of the orbit with the facial and zygomatico- 

 facial nerves. 



The External Nasal Branches (rami nasales externi) supply the skin of the side 

 of the nose and of the septum mobile nasi, and join with the terminal twigs of the 

 nasociliary nerve. 



The Superior Labial Branches (rami labiales superior es; labial branches), the largest 

 and most numerous, descend behind the Quadratus labii superioris, and are dis- 

 tributed to the skin of the upper lip, the mucous membrane of the mouth, and labial 

 glands. They are joined, immediately beneath the orbit, by filaments from the 

 facial nerve, forming with them the infraorbital plexus. 



Sphenopalatine Ganglion (ganglion of Meckel) (Fig. 780). The sphenopalatine 

 ganglion, the largest of the sympathetic ganglia associated with the branches of the 

 trigeminal nerve, is deeply placed in the pterygopalatine fossa, close to the spheno- 



