406 THE ARTERIES OF THE HEAD AND NECK. 



buccinator muscle with the buccal nerve ; it is distributed to the muscles and 

 mucous membrane of the cheek, and anastomoses with the branches of the facial 

 and other arteries of this region. 



C. Of the ihird part. (a) The posterior dental or alveolar branch, arising 

 near the back of the superior maxilla, frequently in common with the infra- 

 orbital branch, runs tortuously downwards upon the zygomatic surface of the bone, 

 and gives off branches which enter the posterior dental canals, and supply the upper 

 molar and bicuspid teeth, besides ramifying in the lining membrane of the maxillary 

 sinus. Other small branches supply the gum. 



( b) The infraorlital artery runs horizontally forwards into the infraorbital canal, 

 and having traversed that canal along with the superior maxillary nerve, emerges 

 upon the face at the infraorbital foramen. 



While in the canal, it sends upwards into the orbit small branches, which enter 

 the inferior rectus and the inferior oblique muscles of the eye and the lachrymal 

 gland, and an anterior dental branch (sometimes two) which descends in the canal of 

 the same name to supply the front teeth and the mucous membrane of the antrum. 

 On the face it gives branches upwards, to the lachrymal sac and inner angle of the 

 orbit, anastomosing with branches of the ophthalmic and facial arteries, and sends 

 other branches downwards, beneath the levator labii superioris, which join the 

 ramifications of the transverse facial, buccal, and facial arteries. 



(c) The descending or superior palatine artery descends through the posterior 

 palatine canal, with the large palatine nerve, and runs along the hard palate, supply- 

 ing the mucous membrane, the glands, and the gum. In front it ends in a small 

 vessel which ascends through the incisor foramen, and anastomoses with the naso- 

 palatine artery. On its way downwards, this artery sends off twigs through the 

 smaller palatine canals, which are distributed to the soft palate and tonsil, and com- 

 municate with the ascending palatine branch of the facial artery. 



(d) The Vidian branch traverses the Yidian canal with the nerve of the same 

 name, and supplies the Eustachian tube, the levator palati muscle, and the upper 

 and lateral part of the pharynx. 



(e) The pterygo-palatine, a very small branch, passes backwards through the 

 pterygo-palatine canal to reach the top of the pharynx, to which, and to the 

 sphenoidal sinus, it is distributed. 



(/) The nasal or spheno-paJatine artery enters the nasal fossa by the spheno- 

 palatine foramen, and divides into branches, some of which ramify extensively over 

 the spongy bones, while others supply the ethmoidal cells, the frontal sinus, and the 

 antrum. One long branch, the naso-paJatine artery or artery of the septum, runs 

 downwards and forwards in the groove on the vomer, and ends in a small vessel 

 which enters the incisor foramen to communicate with the descending palatine 

 artery. 



Varieties. The internal maxillary artery is very constant in its place of origin. It has, 

 however, in several cases been seen to arise from the facial ; and in two instances, after 

 leaving the temporal artery below the angle of the jaw, it pierced the internal pterygoid 

 muscle in its course upwards into the zygomatic fossa (Joessel, W. G-ruber). 



Out of 447 cases (arteries) examined the artery was found to be superficial to the external 

 pterygoid in nearly 55 per cent., and deeper than the muscle in 45 per cent. ; in three 

 instances it pierced the lower head of the muscle ; and in one it passed beneath the whole 

 muscle and emerged between the upper head and the great wing of the sphenoid (J. J. Long). 

 The disposition was in most cases the same on the two sides. When placed beneath the 

 muscle the artery sometimes passed on the inner side also of the inferior dental and lingual 

 nerves, less frequently between the two trunks, the dental being on the outer side of the 

 vessel, and in five instances it pierced the inferior dental. (Report of Committee of Col- 

 lective Investigation of Anat. Soc., by Arthur Thomson, Journ. Anat., xxv, 1890.) 



The deep position of the artery is general among the lower mammals and would appear to 

 be the primary one. When the artery is so placed in man. the common trunk by which the 



