196 



THE SKELETON. 



Development. By a single centre, which makes its appearance soon after 

 ossification of the vertebrae has commenced. 



Articulations. With four bones : two of the cranium, the frontal and ethmoid, 

 and two of the face, the superior maxillary and the inferior turbinated. 



Attachment of Muscles. To one muscle, the Tensor tarsi. 



The Malar Bones. 



The Malar (mala, the cheek) are twp small, quadrangular bones, situated at 

 the upper and outer part of the face : they form the prominence of the cheek, part 

 of the outer wall and floor of the orbit, and part of the temporal and zygomatic 

 fossae. Each bone presents for examination an external and an internal surface ; 

 four processes, the frontal, orbital, maxillary, and zygomatic ; and four borders. 

 The external surface (Fig. 159) is smooth, convex, perforated near its centre by 

 one or two small apertures, the malar foramina, for the passage of nerves and 

 vessels, covered by the Orbicularis palpebrarum muscle, and affords attachment to 

 the Zygomaticus major and minor muscles. 



The internal surface (Fig. 160), directed backward and inward, is concave, 

 presenting internally a rough, triangular surface, for articulation with the supe- 



Bristles passed 



through temporo- 



malar canals. 



With frontal. 



FIG. 159. Left malar bone. Outer surface. 



FIG. 160. Left malar bone. Inner surface. 



rior maxillary bone ; and externally, a smooth, concave surface, which above forms 

 the anterior boundary of the temporal fossa, and below, where it is wider, forms 

 part of the zygomatic fossa. This surface presents, a little above its centre, the 

 aperture of one or two malar canals, and affords attachment to part of two muscles, 

 the Temporal above and the Masseter below. Of the four processes, the frontal 

 is thick and serrated, and articulates with the external angular process of the 

 frontal bone. The orbital process is a thick and strong plate, which projects 

 backward from the orbital margin of the bone. Its supero-internal surface, 

 smooth and concave, forms, by its junction with the orbital surface of the superior 

 maxillary bone and with the great wing of the sphenoid, part of the floor and 

 outer wall of the .orbit. Its infero-external surface, smooth and convex, form* 

 part of the zygomatic and temporal fossae. Its anterior margin is smooth and 

 rounded, forming part of the circumference of the orbit. Its superior margin, 

 rough and directed horizontally, articulates with the frontal bone behind the 

 external angular process. Its posterior margin is rough, and serrated for articu- 

 lation with the sphenoid ; internally it is also serrated for articulation with the 

 orbital surface of the superior maxillary. At the angle of junction of the sphe- 

 noidal and maxillary portions a short, rounded, non-articular margin is generally 

 seen ; this forms the anterior boundary of the spheno-maxillary fissure : occasion- 

 ally, no such non-articular margin exists, the fissure being completed by the direct 

 junction of the maxillary and sphenoid bones or by the interposition of a small 



