THE INTERNAL MAXILLARY ARTERY 555 



thalmic. It enters the cranial cavity through the ethmoidal foramen, passes 

 inward on the cribriform plate, and divides into meningeal and nasal branches. 

 The former ramify in the anterior part of the dura mater and anastomose with 

 branches of the artery of the corpus callosum. The nasal branch passes through 

 the cribriform plate, gives branches to the mucous membrane of the lateral mass 

 of the ethmoid and the adjacent part of the septum nasi, and runs forward on the 

 superior turbinal. 



The third part passes forward in the pterygo-palatine fossa, accompanied l)y 

 branches of the maxillary nerve. On reaching the posterior palatine foramen it 

 is continued by the jialatine artery. Its branches are as follows: 



(1) The buccinator artery (A. buccinatoria) arises from the lower aspect of the 

 internal maxillary shortly after its emergence (Fig. 437). It turns around the max- 

 illary tuberosity, accompanied by the buccinator nerve, and under the masseter 

 muscle, enters the cheek, and runs forward in it. It supplies branches to the 

 cheek, the superior buccal glands, and the masseter and pterygoid muscles. Near 

 its origin it gives off a branch to the orl)ital fat l)ehind the perior])ita. 



(2) The infraorbital or superior dental artery (A. infraorbitalis) arises from 

 the upper aspect of the internal maxillary a little in front of the preceding vessel. 

 It passes upward and forward to the maxillary foramen, runs in the infraorbital 

 canal in company with the nerve of the same name, and is continued forward 

 within the jaw to the incisor teeth. It gives branches to the teeth and gums, and 

 detaches a branch through the infraorbital foramen which anastomoses with the 

 lateral nasal and superior laljial. About midway between its origin and the maxil- 

 lary foramen it gives off the malar or orbital branch (Ramus malaris), which passes 

 along the floor of the orbit to end in the lower litl and anastomose with the angularis 

 oculi. It gives twigs to the inferior oblicjue muscle and the lacrimal sac. 



The infraorbital artery is usually small at its emergence upon the face, but in some cases it 

 is rather large and may partially replace the superior labial and lateral nasal arteries. 



(3) The staphyline or small palatine artery (A. palatina minor) is a small 

 vessel which passes forward in the groove at the inner side of the maxillary tuber- 

 osity to the soft palate. In the groove it is accomjianied by the nerve of the same 

 name and the palatine vein. 



(4) The sphenopalatine artery (A. sphenopalatina) arises in the extreme 

 anterior part of the pterygo-palatine fossa and passes into the nasal cavity, where 

 it divides into internal and external branches. The internal branch is distributed 

 to the mucous membrane of the septum nasi; the external one goes to the inferior 

 turbinal, the inferior meatus, the posterior nares, antl the maxillary and frontal 

 sinuses. It may arise from the infraor})ital. 



(5) The palatine or palato-labial artery (A. palatina major) is the direct con- 

 tinuation of the internal maxillary. It passes through the palatine canal to the 

 roof of the mouth, accompanied by the palatine nerve, and runs forward in the 

 palatine groove, where it is joined by the vein. A little behind the plane of the 

 corner incisor teeth it curves inward over a bar of cartilage to the foramen in- 

 cisivum, where it unites with its fellow of the opposite side. The single artery 

 thus formed passes up through the foramen and divides under the transverse 

 dilator of the nostril into two branches. These ramify in the upper lip and anasto- 

 mose with the lateral nasal and superior labial arteries. In its coiu'se in the roof 

 of the mouth the palatine artery gives off branches to the hard and soft palate and 

 the gimis, and others which pass through the accessory palatine foramina to be 

 distributed in the mucous membrane of the lower part of the nasal cavity. Com- 

 monly two branches, right and left, are detached from the convexity of the arch 

 formed by the union of the two arteries; these run forward in the anterior part of 

 the hard palate. 



