THE SKELETON. 



Fig. 115. Left Lachrymal Bone. 

 External Surface. 



riti Fronfai 



enla-rcjcd j 



part assists in the formation of the lachrymal canal, and lodges the nasal 

 duct. The portion of bone behind the ridge is smooth, slightly concave, and 



forms part of the inner wall of the orbit. The 

 ridge, with a part of the orbital surface imme- 

 diately behind it, affords attachment to the Tensor 

 Tarsi ; the ridge terminates below in a small hook- 

 like process, which articulates with the lachrymal 

 tubercle of the superior maxillary bone, and 

 completes the upper orifice of the lachrymal 

 canal. It sometimes exists as a separate piece, 

 which is then called the lesser lachrymal bone. 

 The internal or nasal surface presents a depressed 

 furrow, corresponding to the ridge on its outer 

 surface. The surface of bone in front of this forms 

 part of the middle meatus; and that behind it 

 articulates with the ethmoid bone, filling in the 

 anterior ethmoidal cells. Of the four border, 

 the anterior is the longest, and articulates with 

 the nasal process of the superior maxillary bone. 

 The posterior, thin and uneven, articulates with 

 the os planum of the ethmoid. The superior, the shortest and thickest, articu- 

 lates with the internal angular process of the frontal bone. The inferior is 

 divided by the lower edge of the vertical crest into two parts ; the posterior 

 part articulates with the orbital plate of the superior maxillary bone ; the an- 

 terior portion is prolonged downwards into a pointed process, which articulates 

 with the lachrymal process of the inferior turbinated bone, and assists in -the 

 formation of the lachrymal canal. 



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

 ossification of the vertebra 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. The Tensor Tarsi. 



THE MALAR BONES. 



The Malar are two 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 internal surface; four processes, 



the frontal, orbital, maxillary, 



Fig. 116. Left Malar Bone. Outer Surface. and zygomatic ; and four bor- 



ders. The external surface (Fig. 

 116) is smooth, convex, perfo- 

 rated 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 

 Zygomaticus Minor muscles. 



The internal surf ace (Vig. 117), 

 directed backwards and in- 

 wards, is concave, presenting 

 internally a rough triangular 

 surface, for articulation with 

 the superior maxillary bone; 



BrisrZfs passed through 



