105 



Foramina ofStenson. 



Foramen of Scarpa,. 



Palate process of { 

 maxilla. 



Horizontal plate 

 of palate bone. 



rior palatine canals. 



laterally to the right and left nasal fossse, and two one in front and one behind 

 lie in the middle line. The former pair of these openings are named the 

 incisor foramina, or foramina of Stenson; they are the openings of the forking incisor 

 canal, through which pass the anterior or terminal branches of the descending 

 or posterior palatine arteries, which ascend from the mouth to the nasal fossse, 

 and they contain the remains of Jacobson's organ. The canals in the middle line 

 are termed the foramina 



of Scarpa, and transmit Anterior palatine canal. 



the nasopalatine nerves, 

 the left passing through 

 the anterior, and the right 

 through the posterior, 

 canal. Occasionally in 

 adults' skulls, often in 

 children's skulls, on the 

 palatal surface of the 

 process a delicate linear 

 suture may sometimes be 

 seen extending from the 

 anterior palatine fossa to 

 the interval between the 

 lateral incisor and the 

 canine tooth. This marks 

 out the premaxillary bones 

 (os incisiuum) on each 

 side, and includes the 

 whole thickness of the 

 alveolus, the correspond- 

 ing part of the floor of 

 the nose, and the anterior 

 nasal spine, and contains 

 the sockets of the incisor teeth; in some animals it exists as a separate bone. The 

 upper surface of the palatal process is concave from side to side, smooth, and 

 forms part of the floor of the nose. It presents the upper orifices of the foramina 

 of Stenson and Scarpa, the former being on each side of the middle line, the 

 latter being situated in the intermaxillary suture, and therefore not visible unless 

 the two bones are placed in apposition. The outer border of the palatal process 

 is incorporated with the rest of the bone. The inner border is thicker in front 

 than behind, and is raised above into a ridge, the nasal crest (crista nasalis), 

 which, with the corresponding ridge in the opposite bone, forms a groove for 

 the reception of the vomer. In front this crest rises to a considerable height, and 

 this portion is named the incisor crest. The anterior margin is bounded by the 

 thin, concave border of the opening of the nose, prolonged forward internally into 

 a sharp process, forming, with a similar process of the opposite bone, the anterior 

 nasal spine (spina nasalis anterior). The posterior border is serrated for articu- 

 lation with the horizontal plate of the palate bone. 



Development. This bone commences to ossify at a very early period, and ossification 

 proceeds in it with great rapidity, so that it is difficult to ascertain with certainty its precise 

 number of centres. It appears, however, probable that it is ossified from six centres, 

 which develop in membrane: (1) One, the orbitotutxal, which forms that portion of the body 

 of the bone which lies internal to the infraorbital canal, including the floor of the orbit, the 

 outer wall of the nasal fossa, and the nasal process. (2) A malar, which gives origin to that 

 portion of the bone which lies external to the infraorbital canal and the malar process. (3) 

 A palalal, from which is developed the palatal process posterior to Stenson's canal and the 



Accessory palatine foramina. 



FIG. 72. The palate and alveolar arch. 



