46 TEE BONES. 



opens into the incisiye foramen. These three faces are separated by as 

 many borders: two internal, limiting before and behind the corresponding 

 face : and an external, separating the labial from the buccal face, ihe latter 

 only merits notice ; it is very thick, and is divided into two parts : an 

 inferior which describes a curved line with, the concavity upwards, and 

 is hollowed by three alveoli to receive the incisor teeth; another, the 

 superior is straight, vertical, and somewhat sharp, and forms a part of 

 the dental interspace. It is limited above, near the base of the external 

 process by a cavity for the formation of the alveolus of the tusk. 



' Processes. — These are distinguished as ea;- 



Fig. 21. ternal and internal. The first, the longest and 



strongest, is flattened on both sides ; its ex- 

 ternal face is smooth and continued with that 

 of the thick portion of the bone ; its internal 

 face is covered by the mucous membrane of 

 the nose ; the anterior border is smooth and 

 rounded; the posterior, denticulated to re- 

 spond to the supermaxillary bone, is in con- 

 tact with the external border of the base ; its 

 summit is thin, and is insinuated between the 

 latter and the nasal bone. The internal pro- 

 cess, the smallest, is flattened from before to 

 behind, and forms a very thin tongue of bone, 

 separated from the other portions by a nar- 

 row and very deep notch named the incisive 

 opening or cleft. Its inferior face constitutes a 

 small portion of the floor of the nasal fossae ; 

 the posterior, continuous with the same face 

 of the principal mass of the bone, forms part 

 of the palatine roof ; its external border cir- 

 cumscribes, inwardly, the incisive opening ; 

 the internal is united by dentated suture with 

 the opposite bone. 



Structure and development. — It is a spongy 

 bone, developed from a single nucleus. 



3. Palate Bones. 



Ihe palate hones are situated between the 



supermaxillaries, at the margin of the guttural 



opening of the nasal cavities, and are articu- 



posTEPjoR ASPECT OF hokse's ^^ted wlth the sphenoid, ethmoid, vomer, 



SKULL. frontal, and pterygoid bones. Elongated from 



1, Occipital protuberance; 2, above to below, flattened laterally, and curved 



Foramen inag:num ; 3, 3, Oc- 

 cipital condyles ; 4, 4, Styloid processes ; 5, 5, Petrous bone ; 6, Basilar process ; 7, 

 Pterygoid fissure of the sphenoid bone ; 8, Foramen lacerura ; 9, 9, Supra-condyloid, or 

 anterior mastoid process; 10, 10, Articular eminence, or temporal condyle; 11, Body ot 

 sphenoid bone; 12, Pterygoid process; 13, Ethmoid bone; 14, Temporal bone and sphe- 

 noidal suture; 15, Lachrymal bone; 16, Vomer; 17, Malar boie ; 18, Maxillary tube- 

 rosity ^ 19, Posterior, or guttural opening of the nose; 20, Palate bone; 21, Palatine 

 styloid process ; 22, Palato-maxiUary foramen ; 23, Palatine process of superior maxil- 

 lary bone with suture ; 24, Ditto of premaxillary bone ; 25, Premaxillary bone ; 26, 

 Upper incisor teeth ; 27, Point of junction of the premaxillary with the superior maxil- 

 lary bone ; 28, Upper molar teeth — yoang mouth. 



