THE BONES. 59 



face ; margo eocternus, posterior, free ; between it and the larger wings of the 

 sphenoid bone -fissura orb. inferior. 



d. Internal, nasal surface, with the opening of the antrum Highmori, before 

 it Crista turbinalis inferior, for the inferior concha in the formation of the lacry- 

 mal canal ; sulcus pterygo-palat., helping to form canal, ptery.-pal, at the pos- 

 terior part. 



Sinus maxillaris s. antrum Highmori, pyramid-shaped, with very thin supe- 

 rior, orbitar, and inferior walls, particularly over 'the sockets of the Canine 

 and first Bicuspid teeth, connected with the sin. pterygoid. and Jugal. Its ir- 

 regular opening contracted by the inferior nasal concha, Palate and Ethmoid 

 bones to a small foramen opening beneath the inferior turbinate bone. It is 

 lined with a delicate periosteum and ciliated epithelium, not mucous mem- 

 brane. (Henle.) 



2. Processes: a. Proc. nasalis s. front alls, internal, superior process, with an 

 external surface, for m. levator lab. super, alceque nasi ; and an internal, con- 

 cave, on which are lineee turbinattg s. transversce, for the middle and inferior 

 nasal concha ; farther, the anterior border unites with the nasal bone, the pos- 

 terior thick border with a groove, sulcus lacrymalis, which continues into the 

 Canal, lacrymal. The apex lies in the fissure of the frontal bone. 



b. Proc. zygomaticus, external superior process unites with the malar bone. 



c. Proc. alveolaris, the process for the sockets of the teeth, that is, the infe- 

 rior thick border of the upper jaw, contains eight cells for teeth, alveoli, with 

 projections and depressions ; at the point of union of the two upper jaws, 

 Spina nasalis anterior ; behind that, the Canalis incisivus, for the nerv. naso- 

 palatin. Scarpce, and arteria sphenopalatin., leads from the nasal into the buccal 

 cavity ; the foram. incisivum is sometimes double. 



d. Proc. palatinus, palate process ; this, the horizontal roof of the mouth and 

 the floor of the nose, unites internally with the palate process of the other 

 side, behind with the horizontal portion of the palate bone ; thence arise the 

 sutura palatina and cruciata, and Crista nasalis, for the Vomer upon the upper 

 surface. 



Tissue of the upper jaw. Spongy substance is only present 

 in the alveolar and malar processes. The entire bone is very 

 light. 



Development. The first point of ossification appears from the 

 35th to the 55th day of embryonic existence in the alveolar pro- 

 cess. A centre of ossification is probably found in the position 

 of the intermaxillary bone of mammalia, Os incisivum (Hare 

 lip an arrest of the development of this bone) ; likewise one for 

 canal is infra-orbit alls. 



At birth the upper jaw is very small; nevertheless the antrum 

 of Highmore is already present. 



60. 2. Ossa Palatina, Palate bones, 2. 



Situation, at the posterior part of the nasal cavity, and behind 

 the palate processes of the upper jaw, before, and in, the Ptery- 

 goid processes of the Sphenoid. 



