THE MAXILLA 



89 



constitutes the larger part of the floor of the nasal fossa. The inferior surface is 

 vaulted, rough, and perforated with foramina for nutrient vessels. Near its 

 lateral margin is a longitudinal groove for the transmission of the vessels and 

 nerves which issue at the posterior palatine canal and course along the lower 

 aspect of the palate. When the bones of the two sides are placed in apposition, a 

 large orifice may be seen in the middle line immediately behind the incisor teeth. 

 This is the incisive foramen, at the bottom of which are four foramina. Two are 

 small and arranged one behind the other exactly in the meso -palatine suture. 

 These are the foramina of Scarpa and transmit the naso-palatine nerves, the left 



Fig. 111.- 



-Section of Maxilla to show the Floor of the Maxillary Antrxj-m. 

 (Reduced \.) 



Bony process 



passing through the anterior and the right through the posterior aperture. The 

 lateral and larger orifices are the foramina of Stenson, representing the lower 

 apertures of two passages by which the nose communicates wdth the mouth; they 

 transmit some terminal branches of the descending palatine artery to the nasal 

 fossae, and lodge recesses of the nasal mucous membrane and remnants of 

 Jacobson's organs. 



Fig. 112. — Maxilla and Zygomatic Bone, to show Muscular Attachments. (Poirier.) 



Inferior oblique 



Orbicularis oculi 



Quadrate mu?cle. 

 angular head 



Quadrate muscle, 

 zygomatic head 



Zygomaticus 



Masse ter 



Quadrate muscle, 

 infraorbital head 



Dilator naris posterior 



Nasalis vtransverse 

 portion; 



Nasalis (alar portion) 



Caninus 



Buccinator 



Running laterally from the incisive foramen to the space between the second incisor and 

 canine tooth, an indistinct suture may sometimes be seen, indicating the hne of junction of the 

 maxillary and pre-maxillary portions of the bone. The premaxilla or incisive bone is the part 

 which bears the incisor teeth and in some animals exists throughout hfe as an mdependent 

 element. The posterior border of the palate process is rough and serrated for articulation with 



