THE MALAR J3OJVE 107 



of bone in front of this ridge, the lacrimal sulcus (sulcus lacrimal is), presents 

 a smooth, concave, longitudinal groove, the free margin of which unites with 

 the nasal process of the maxilla, completing the lacrimal canal. The upper part 

 of this groove (fossa sacci lacrimalis) lodges the lacrimal sac; the lower part (sul- 

 cus lacrimalis} 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 immediately behind it, affords origin to the 

 Tensor tarsi muscle; it terminates below in a small, hook- 

 like projection, the hamular process (hamulus lacrimalis), with frontal. 

 which articulates with the lacrimal tubercle of the maxilla 

 and completes the upper orifice of the lacrimal groove. It 

 sometimes exists as a separate piece, which is then called 

 the lesser lacrimal bone. 



The internal or nasal surface presents a depressed furrow, 

 corresponding to the ridge on its outer surface. The sur- 

 face of bone in front of this forms part of the middle 

 meatus, and that behind it articulates with the ethmoid 

 bone, closing in the anterior ethmoidal cells. 



Borders. Of the four borders, the anterior is the long- in/eri r 

 est, and articulates with the nasal process of the maxilla. FIG. 74. Left lacrimal 



r^, ,i j . i . -i.i-.ti bone. External surface. 



1 he posterior, thin and uneven, articulates with the os (Slightly enlarged.) 

 planum of the ethmoid. The superior, the shortest and 



thickest, articulates 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 maxilla; the anterior 

 portion is prolonged downward into a pointed process, w r hich articulates with 

 the lacrimal process of the turbinated bone and assists in the formation of the 

 lacrimal canal. 



Development. From a single centre, which makes its appearance in membrane at about 

 the eighth or ninth week. 



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

 the face, the maxilla and the turbinated. 



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



The Malar Bone (Os Zygomaticum) . 



The malar bone is a quadrangular bone, situated at the upper and outer part of 

 the face. It forms the prominence of the cheek, part of the outer wall and floor 

 of the orbit, and part of the temporal and zygomatic fossae (Fig. 75). Each bone 

 presents for examination an external and an internal surface; four processes, the 

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



Surfaces. The external surface (fades malaris) (Fig. 76) is smooth, convex, 

 perforated near its centre by a small aperture, the malar foramen (foramen zygo- 

 maticofaciale), for the passage of nerves and vessels from the orbit. The malar 

 surface is covered by the Orbicularis palpebrarum muscle, and affords attachment 

 to the Zygomaticus major and minor muscles. 



The internal surface (fades temporalis) (Fig. 77), directed backward and inward, 

 is concave, presenting anteriorly a rough, triangular surface, for articulation with 

 the maxilla; and behind, 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 

 a malar canal (foramen zygomaticolemporale}, and affords attachment at its lower 

 part to a portion of the Masseter muscle. 



