SUPERIOR MAXILLARY BONES. 43 



articulated skull by the ethmoid, palate, lachrymal, and inferior turbi- 

 nated bones. The cavity of the antrum is somewhat triangular, corre- 

 sponding in shape with the form of the body of the bone. Upon its 

 inner wall are numerous grooves, lodging branches of the superior max- 

 illary nerve, and projecting into its floor several conical processes, corre- 

 sponding with the roots of the first and second molar teeth. In front 

 of the opening of the antrum is the strong ascending plate of the nasal 

 process, marked inferiorly by a rough horizontal ridge (crista turbina- 

 lis inferior), which gives attachment to the inferior turbinated bone. 

 The concave depression immediately above this ridge corresponds with 

 the middle meatus of the nose, and that below the ridge with the in- 

 ferior meatus. Between the nasal process and the opening of the 

 antrum, is a deep groove (sulcus lachrymalis) which is converted 

 into a canal by the lachrymal and inferior turbinated bone, and con- 

 stitutes the nasal duct. The superior border of the nasal surface is 

 irregularly cellular, and articulates with the lachrymal and ethmoid 

 bone ; the posterior border is rough, and articulates with the palate 

 bone ; the anterior border is sharp, and forms the free margin of the 

 opening of the nose ; and from the inferior border projects inwards 

 a strong horizontal plate, the palate process. 



The posterior surface may be called zygomatic, from forming part of 

 the zygomatic fossa ; it is bounded externally by the malar process, and 

 internally by a rough and rounded border, the tuf>erosity, which is 

 pierced by a number of small foramina (foramina alveolaria posteriora), 

 giving passage to the posterior dental nerves and branches of the 

 superior dental artery. The lower part of this tuberosity presents a 

 rough oval surface, to articulate with the palate bone, and immediately 

 above and to the inner side of this articular surface a smooth groove, 

 which forms part of the posterior palatine canal. The superior border 

 is smooth and rounded to form the lower boundary of the spheno- 

 maxillary fissure, and is marked bv a notch, the commencement of the 

 infra-orbital canal. The inferior boundary is the alveolar process, 

 containing the two last molar teeth. 



The orbital surface is triangular and thin, and constitutes the floor 

 of the orbit. It is bounded internally by an irregular edge, which 

 articulates with the palate, ethmoid, and lachrymal bone ; posteriorly, 

 by the smooth border which enters into the formation of the spheno- 

 maxillary fissure ; and, anteriorly, by a convex margin, partly smooth 

 and partly rough, the smooth portion forming part of the lower margin 

 of the orbit, and the rough articulating with the malar bone. The 

 middle of this surface is channelled by a deep groove and canal, the 

 infra-orbital, which terminates at the infra- orbital foramen ; and near 

 to the root of the nasal process is a slight depression, marking the 

 origin of the inferior oblique muscle of the eyeball. 



The four processes of the superior maxillary bone are the nasal, 

 malar, alveolar, and palate. 



The nasal process ascends by the side of the nose, to which it forms 

 the lateral boundary, and articulates with the frontal and nasal bone. 



