MALAR BONES. 



165 



Fig. 117. Left Malar Bone. Inner Surface. 



and externally, a smooth con- 

 cave surface, which forms the 

 anterior boundary of the tem- 

 poral fossa above; and below, 

 where it is wider, forms part of 

 the zygomatic fossa. This sur- 

 face presents, a little above its 

 centre, the aperture of one or 

 two malar canals, and affords 

 attachment to part of two mus- 

 cles, the Temporal above and 

 the Masseter below. The fron- 

 tal process is thick and serrated, 

 and articulates with the exter- 

 nal angular process of the fron- 

 tal bone. The orbital process is 

 a thick and strong plate, which 

 projects backwards from the 

 orbital margin of the bone. Its 

 upper surface, smooth and concave, forms, by its junction with the great ala of 

 the sphenoid, the outer wall of the orbit. Its under surface, smooth and con- 

 vex, forms part of the temporal fossa. 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 

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

 generally seen: this forms the anterior boundary of the spheno-maxillary 

 fissure ; occasionally, 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 Wormian bone in the angular interval between 

 them. On the upper surface of the orbital process are seen the orifices of one or 

 two temporo-malar canals ; one of these usually opens on the posterior surface, 

 the other (occasionally two), on the facial surface: they transmit filaments 

 (temporo-malar) of the orbital branch of the superior maxillary nerve. The 

 maxillary process is a rough triangular surface, which articulates with the supe- 

 rior maxillary bone. The zygomatic process, long, narrow, and serrated, articu- 

 lates with the zygomatic process of the temporal bone. Of the four borders, the 

 superior or orbital is smooth, arched, and forms a considerable part of the 

 circumference of the orbit. The inferior, or zygomatic, is continuous with the 

 lower border of the zygomatic arch, affording attachment by its rough edge to 

 the Masseter muscle. The anterior or maxillary border is rough, and bevelled 

 at the expense of its inner table, to articulate with the superior maxillary bone; 

 affording attachment by its outer margin to the Levator Labii Superioris Pro- 

 prius, just at its point of junction with the superior maxillary. The posterior 

 or temporal border, curved like an italic /, is continuous above with the com- 

 mencement of the temporal ridge; below, with the upper border of the zygo- 

 matic arch : it affords attachment to the temporal fascia. 



Development. By a single centre of ossification, which appears at about the 

 same period when ossification of the vertebra commences. 



Articulations. With four bones : three of the cranium, frontal, sphenoid, 

 and temporal ; and one of the face, the superior maxillary. 



Attachment of Muscles. Levator Labii Superioris Proprius, Zygomaticus 

 Major, Zygomaticus Minor, Masseter, and Temporal. 



