

trf/Si Fron/al 



' With 



Infer, nasal concha 

 FIG. 163. Left lacri- 

 mal bone. Orbital sur- 

 face. Enlarged. 



Surfaces. The lateral or orbital surface (Fig. 163) is divided by a vertical ridge, 

 the posterior lacrimal crest, into two parts. In front of this crest is a longitudinal 

 groove, the lacrimal sulcus (sulcus lacrimalis), the inner margin of which unites 

 with the frontal process of the maxilla, and the lacrimal fossa is thus completed. 

 The upper part of this fossa lodges the lacrimal sac, the lower part, the naso- 

 lacrimal duct. The portion behind the crest is smooth, and forms part of the 

 medial wall of the orbit. The crest, with a part of the orbital surface imme- 

 diately behind it, gives origin to the lacrimal part of the Orbicularis oculi and 

 ends below in a small, hook-like projection, the lacrimal hamulus, which articu- 

 lates with the lacrimal tubercle of the maxilla, and completes 

 the upper orifice of the lacrimal canal; it sometimes exists as 

 a separate piece, and is then called the lesser lacrimal bone. 



The medial or nasal surface presents a longitudinal furrow r , 

 corresponding to the crest on the lateral surface. The area in 

 front of this furrow forms part of the middle meatus of the 

 nose; that behind it articulates with the ethmoid, and completes 

 some of the anterior ethmoidal cells. 



Borders. Of the four borders the anterior articulates with 

 the frontal process of the maxilla; the posterior with the lamina 

 papyracea of the ethmoid; the superior with the frontal bone. 

 The inferior is divided by the lower edge of the posterior lacri- 

 mal crest into two parts : the posterior part articulates with the 

 orbital plate of the maxilla; the anterior is prolonged downward 

 as the descending process, which articulates with the lacrimal process of the inferior 

 nasal concha, and assists in forming the canal for the nasolacrimal duct. 



Ossification. The lacrimal is ossified from a single center, which appears about the twelfth 

 week in the membrane covering the cartilaginous nasal capsule. 



Articulations. The lacrimal articulates with four bones: two of the cranium, the frontal 

 and ethmoid, and two of the face, the maxilla and the inferior nasal concha. 



The Zygomatic Bone (Os Zygomaticum; Malar Bone). 



The zygomatic bone is small and quadrangular, and is situated at the upper 

 and lateral part of the face: it forms the prominence of the cheek, part of the 

 lateral wall and floor of the orbit, and parts of the temporal and infratemporal 

 fossae (Fig. 164). It presents a malar and a temporal surface; four processes, the 

 frontosphenoidal, orbital, maxillary, and temporal; and four borders. 



Surfaces. The malar surface (Fig. 165) is convex and perforated near its center 

 by a small aperture, the zygomaticof acial foramen, for the passage of the zygomatico- 

 facial nerve and vessels; below this foramen is a slight elevation, which gives 

 origin to the Zygomaticus. 



The temporal surface (Fig. 166), directed backward and medialward, is concave, 

 presenting medially a rough, triangular area, for articulation with the maxilla, 

 and laterally a smooth, concave surface, the upper part of which forms the anterior 

 boundary of the temporal fossa, the lower a part of the infratemporal fossa. Near 

 the center of this surface is the zygomaticotemporal foramen for the transmission 

 of the zygomaticotemporal nerve. 



Processes. The frontosphenoidal process is thick and serrated, and articulates 

 with the zygomatic process of the frontal bone. On its orbital surface, just within 

 the orbital margin and about 11 mm. below the zygomaticofrontal suture is a 

 tubercle of varying size and form, but present in 95 per cent, of skulls (Whitnall 1 )- 



1 Journal of Anatomy and Physiology, vol. xlv. The structures attached to this tubercle are: (1) the check 

 ligament of the Rectus lateralis; (2) the lateral end of the aponeurosis of the Levator palpebrse superioris; (3) the 

 suspensory ligament of the eye (Lockwood) ; and (4) the lateral extremities of the superior and inferior tarsi. 



