THE SUPERIOR MAXILLARY BONE. 45 



directed backwards from the anterior to the posterior border, from the latter 

 of which, however, in young bones the lamina remains disconnected. In front 

 of this canal the mesial border of the bone rises to a considerably greater height 

 than behind it, forming, with its neighbour, the nasalcrest a grooved elevation 

 which supports the extremity of the vomer and the septal cartilage, and is pro- 

 longed forwards into the nasal spine. Each incisor foramen widens out below 

 into a larger hollow, which, when placed in apposition with its fellow, com- 

 pletes a mesial aperture, the anterior palatine foramen. Viewed from below, 

 this aperture may be seen to be divided into four smaller foramina, two of which 

 placed laterally are the incisor foramina, called also/oramma of Stenson, while 

 the other two, placed in the middle line, one before the other, are distinguished 

 as the foramina of Scar-pa. The whole communication between the nose and 

 the palate may be designated collectively as the anterior palatine canal. 



The terms incisor foramen and anterior palatine canal are often used convertibly 

 and vaguely to express what has been above defined as the anterior palatine canal, or 

 its inferior opening. According to the definitions here given, incisor foramen has 

 the same meaning in human as in comparative anatomy while anterior palatine canal 

 is restricted to an appearance which presents itself only in man and a few animals. 

 The lamina passing backwards from before each incisor foramen corresponds to the 

 mesial palatine process of the intermaxillary bone in other animals, e. gr.,the carnivora: 

 while the incisor foramina are those which are seen largely developed in those 

 animals, and are the remains of a primitive communication between the nose and 

 mouth. The foramina of Scarpa lie in the suture between the laminae referred to. 

 They transmit the naso-palatine nerves; the nerve of the right side occupying, 

 according to Scarpa, the posterior one, which is usually largest, and that of the left 

 side, the anterior : but they are very inconstant. (Scarpa, Annot. Anatom., 

 lib. ii. cap. 5.) 



Fig. 39. FRONT PART OP THE PALATE AND Fig. 39. 



ALVEOLAR ARCH OF AN ADULT. 

 Showing the lower opening of the anterior palatine 

 or incisor foramen. 1, 2, are placed on the palate plates 

 of the two superior maxillary bones ; 4, anterior pa- 

 latine foramen, in which is seen a partial division into 

 four openings the two lateral, with lines pointing to 

 them from 1 and 2, are the incisor foramina (foramina 

 of Stenson) ; the anterior and posterior, indicated by 

 3 and 4, are the naso-palatine, or foramina of Scarpa. 



The external surface is divided into an anterior and a posterior part by 

 the malar process, a prominence presenting a large triangular roughness for 

 articulation with the malar bone, which abuts by its upper border 

 against the edge of the orbital surface, and at its inferior angle projects 

 outwards and downwards above the first molar tooth. The anterior 

 portion is excavated in a smooth curved notch at its internal margin 

 for the opening of the anterior nares. It is marked by a prominence 

 corresponding to the position of the fang of the canine tooth ; and in- 

 ternal to this is a slight depression, the incisor or myrtiform fossa ; while 

 between it and the malar process is the much deeper canine fossa, in 

 which arise the levator anguli oris and compressor nasi muscles. Above the 

 canine fossa, immediately below the margin of the orbit, is the infra-orbital 

 foramen, which transmits the superior maxillary nerve. The posterior 

 portion looks partly into the zygomatic, partly into the pterygo-maxillary 

 fossa. It exhibits a convexity, the tuber osity, which projects, backwards, 

 and is perforated by a number of foramina transmitting the superior dental 

 nerves and arteries. 



