218 



THE SKELETON. 



lachrymal, and palate ; but three of these, the frontal, ethmoid, and sphenoid, 

 enter into the formation of both orbits, so that the two cavities are formed of 

 eleven bones only. Each cavity presents for examination a roof, a floor, an inner 

 and an outer wall, four angles, a circumference or base, and an apex. The roof 

 is concave, directed downward and forward, and formed in front by the orbital 

 plate of the frontal ; behind by the lesser wing of the sphenoid. This surface 

 presents internally the depression for the cartilaginous pulley of the Superior 

 oblique muscle ; externally, the depression for the lachrymal gland ; and 

 posteriorly, the suture connecting the frontal and lesser wing of the sphenoid. 



TENDO OCUU 



Groove for 

 facial artery 



FIG. 175. Antero-lateral region of the skull. (Cryer.) 



The floor is nearly flat, and of less extent than the roof; it is formed chiefly 

 by the orbital surface of the superior maxillary ; in front, to a small extent, by the 

 orbital process of the malar, and behind, by the superior surface of the orbital 

 process of the palate. This surface presents at its anterior and internal part, just 

 external to the lachrymal groove, a depression for the attachment of the Inferior 

 oblique muscle ; externally, the suture between the malar and superior maxillary 

 bones ; near its middle, the infraorbital groove ; and posteriorly, the suture between 

 the maxillary and palate bones. 



The inner wall is flattened, and formed from before backward by the nasal 

 process of the superior maxillary, the lachrymal, os planum of the ethmoid, and a 

 small part of the body of the sphenoid. This surface presents the lachrymal 

 groove and crest of the lachrymal bone, and the sutures connecting the lachrymal 



