THE TRIANGLES OF THE NECK 605 



The infraorbital (a. infraorbitalis) appears, from its direction, to be the con- 

 tinuation of the trunk of the internal maxillary, but often it arises from that vessel 

 in conjunction with the preceding branch. It runs along the infraorbital canal 

 with the superior maxillary nerve, and emerges upon the face at the infraorbital 

 foramen, beneath the Levator labii superioris muscle. While in the canal, it 

 gives off (a) branches which ascend into the orbit, and assist in supplying the 

 Inferior rectus and Inferior oblique muscles and the lacrimal gland, and (6) the 

 anterior dental branches (aa. alveolares superiores anteriores}, which descend through 

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

 ant rum and the front teeth of the maxilla. On the face, some branches pass 

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

 the angular branch of the facial artery; others run inward toward the nose, anas- 

 tomosing with the nasal branch of the ophthalmic; and others descend beneath the 

 Levator labii superioris muscle, 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 sphenomaxillary fossa. 



The descending palatine (a. palatina ^escendens) descends through the posterior 

 palatine canal with the anterior palatine branch of the sphenopalatine (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 

 incisive canal (foramen of Stenson) to anastomose with the nasopalatine artery. 

 Branches are distributed to the gums, the mucous membrane of the hard palate, 

 and the palatine glands. 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. 



Applied 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 the vessel is in danger of being wounded, and may give rise to formidable hemorrhage. In 

 case it should be wounded it may be necessary to plug the posterior palatine canal in order to 

 arrest the bleeding. 



The Vidian branch (a. canalis pterygoidei) 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 anasto- 

 moses with the other tympanic arteries. 



The pterygo palatine, a very small branch, runs backward through the pterygo- 

 palatine canal with the pharyngeal nerve, and is distributed to the upper part of 

 the pharynx and Eustachian tube. 



The naso- or sphenopalatine (a. sphenopalatind) passes through the spheno- 

 palatine foramen into the cavity of the nose, at the back part of the superior meatus, 

 and divides into several branches. One, the nasopalatine, or artery of the septum, 

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

 mucous membrane, and anastomoses in front with the terminal branch of the de- 

 scending palatine; the other branches, two or three in number, are distributed to 

 the lateral wall of the nose, the antrum, and to the ethmoidal and sphenoidal cells. 



THE TRIANGLES OF THE NECK (Fig. 446). 



The student having considered the relative anatomy of the large arteries of the 

 neck and their branches, and the relations they bear to the veins and nerves, should 

 now examine these structures collectively, as they present themselves in certain 



