Fig. 27.—Maxillary Bone, Lateral Surface.
Fig. 28.—Maxillary Bone, Medial Surface.
a, body; b, frontal process; c, infraorbital foramen; d, elevation for root of canine tooth; e, canine tooth; f, first premolar; g, second premolar; h, third premolar; i, molar tooth; j, zygomatic process; k, beginning of lachrymal canal; l, ridge to which the ventral nasal concha is attached; m, nasal crest of palatine process.
The body (a) has the form of a triangular prism whose broader dorsal face looks into the nasal cavity and orbit, while the ventral face looks into the mouth, and the lateral face toward the cheek. From the junction of the dorsal and lateral surfaces at the cranial end the large flat curved frontal process (b) passes dorsad, while the teeth are implanted along the border, alveolar border or process, formed by the junction of the ventral and lateral surfaces.
The lateral surface is continuous with the lateral surface of the frontal process and shows at the base of the frontal process on its caudal border the large infraorbital foramen ([Fig. 27], c), for the vessels and nerves of the same name. Near the medial end of the surface is a cylindrical elevation (d) for the root of the canine tooth (e).
The ventral surface is smooth and looks into the roof of the mouth.
On the dorsal surface caudal and cranial halves may be distinguished. The caudal one-half enters into the floor of the orbit. The lateral edge of this portion is divided into two laminæ, between which is received the end of the malar bone. Caudad this edge is prolonged into the short dorsally directed zygomatic process (j). The cranial half of the dorsal surface looks into the nasal cavity and is separated from the caudal half by a sharp vertical lamina of bone which runs caudomediad from the base of the nasal process. To the dorsal edge of this lamina are articulated the lachrymal bone and a part of the palatine. At the point where the lamina joins the base of the nasal process a foramen is seen leading into a canal, the nasolachrymal canal (k). Craniad of the lamina the surface is concave. Where it becomes continuous with the inner edge of the frontal process there is attached to it a thin bone, the ventral nasal concha (or maxilloturbinal), which is rolled into an irregular spiral. The nasolachrymal canal opens ventrad of its cranial end.
The cranial third of this part of the bone projects further mediad than does the rest of the medial border, forming thus the broad palatine process. This is rough on its medial edge for articulation with the premaxillary and the palatine process of the opposite bone. This medial edge rises also dorsally into a low ridge, the nasal crest (m), which is roughened for articulation with the vomer. The caudal two-thirds of the medial edge articulates with the palatine bone.