BRANCHES OF THE EXTERNAL CAROTID. 499 



BRANCHES OF THE THIRD OR SPHENO-MAXILLARY PORTION. 



Alveolar. Vidian. 



Infra-orbital. Pterygo-palatine. 



Posterior or Descending Palatine. Naso- or Spheno-palatine. 



The alveolar or posterior dental branch is given off from the internal maxillary 

 by a common branch with the infra-orbital, and just as the trunk of the vessel is 

 passing into the spheno-maxillary fossa. Descending upon the tuberosity of the 

 superior maxillary bone, it divides into numerous branches, some of which enter 

 the posterior dental canals, to supply the molar and bicuspid teeth and the lining 

 of the antrum, and others are continued forward on the alveolar process to supply 

 the gums. 



The infra-orbital appears, from its direction, to be the continuation of the trunk 

 of the internal maxillary. It arises from that vessel by a common trunk with the 

 preceding branch, and runs along the infra-orbital canal with the superior maxil- 

 lary nerve, emerging upon the face at the infra-orbital foramen, beneath the Levator 

 labii superioris. Whilst contained in the canal, it gives off branches which ascend 

 into the orbit, and assist in supplying the Inferior rectus and Inferior oblique 

 muscles and the lachrymal gland. Other branches (anterior dental) descend 

 through the anterior dental canals in the bone, to supply the mucous membrane of 

 the antrum and the front teeth of the upper jaw. On the face, some branches pass 

 upward to the inner angle of the orbit and the lachrymal sac, anastomosing with 

 the angular branch of the facial artery ; other branches pass inward toward the 

 nose, anastomosing with the nasal branch of the ophthalmic ; and other branches 

 descend beneath the Levator labii superioris, and anastomose with the transverse 

 facial and buccal arteries. 



The four remaining branches arise from that portion of the internal maxillary 

 which is contained in the spheno-maxillary fossa. 



The descending palatine descends through the posterior palatine canal with the 

 anterior palatine branch of Meckel's ganglion, and, emerging from the posterior 

 palatine foramen, runs forward in a groove on the inner side of the alveolar border 

 of the hard palate to the anterior palatine canal, where the terminal branch of the 

 artery passes upward through the foramen of Stenson to anastomose with the naso- 

 palatine artery. Its branches are distributed to the gums, the mucous membrane of 

 the hard palate, and the palatine glands. Whilst it is contained in the palatine 

 canal it gives off branches which descend in the accessory palatine canals to supply 

 the soft palate and tonsil, anastomosing with the ascending palatine artery. 



Surgical Anatomy. The position of the descending palatine artery on the hard palate 

 should be borne in mind in performing an operation for the closure of a cleft in the hard palate, 

 as it is in danger of being wounded, and may give rise to formidable hemorrhage. In one case 

 in which it was wounded it was necessary to plug the posterior palatine canal in order to arrest 

 the bleeding. 



The Vidian branch passes backward along the Vidian canal with the Vidian 

 nerve. It is distributed to the upper part of the pharynx and Eustachian tube, 

 sending a small branch into the tympanum, which anastomoses with the other 

 tympanic arteries. 



The pterygo-palatine is a very small branch, which passes backward through 

 the pterygo-palatine canal with the pharyngeal nerve, and is distributed to the 

 upper part of the pharynx and Eustachian tube. 



The spheno-palatine passes through the spheno-palatine foramen into the 

 cavity of the nose, at the back part of the superior meatus, and divides into 

 two branches : one internal, the naso-palatine or artery of the septum, passes 

 obliquely downward and forward along the septum nasi, supplies the mucous 

 membrane, and anastomoses in front with the terminal branch of the descending 

 palatine. The external branches, two or three in number, supply the mucous 

 membrane covering the lateral wall of the nose, the antrum, and the ethmoid and 

 sphenoid cells. 



