DISSECTING MANUAL. 



It is separated from the inner wall by a rather horizontal su- 

 ture; and from the outer wall by the sphenoidal fissure behind 

 and sutures in front. On the inner boundary, in the fronto- 

 ethmoidal suture, are two foramina (anterior and posterior 

 ethmoidal canals). A depression, or spine, for the pulley of 

 the Superior oblique, lies just behind the inner part of the or- 

 bital margin of the frontal, while a shallow fossa, for the lach- 

 rymal gland, lies under cover of the external angular process 

 of the frontal. [149] 



The floor is formed by the orbital plate of the superior max- 

 illa, the orbital surface of the malar, and posteriorly a small 

 triangular area on the orbital process of the palate bone. Ex- 

 ternally a cleft (spheno-maxillary fissure) separates the superior 

 maxilla from the great wing of the sphenoid. Internally the 

 floor is separated from the inner wall by a line of sutures 

 which end anteriorly, opposite the lachrymal bone, at the 

 canal (lachrymal). A canal (infra-orbital) runs sagittally 

 under the floor to the face ; posteriorly its roof is deficient and 

 a groove leads from it to the spheno-maxillary fissure. [149] 



The outer wall is formed by the great wing of the sphenoid 

 and orbital surface of the malar. It is limited below by the 

 spheno-maxillary fissure posteriorly ; and above by the sphe- 

 noidal fissure posteriorly and a line of sutures anteriorly. One 

 or two small (orbital) canals run through the malar bone an- 

 teriorly to the temporal fossa. [151] 



The inner watt is formed, from before backward, by the 

 frontal process of the superior maxilla, the lachrymal, the side 

 (os planum) of the lateral mass of the ethmoid, and part of the 

 side of the body of the sphenoid. It is limited above and 

 below by lines of sutures. The lachrymal bone presents a 

 mesial vertical ridge (lachrymal crest), and in front of this a 

 hollow (lachrymal groove), for the lachrymal sac, which is 

 completed by the frontal process of the superior maxilla; a 

 canal for the nasal duct descends from the groove to the nasal 

 fossa. [151] 



[6] 



