GENERAL REMARKS ON THE SKULL. 



orbital vessels and nerve ; and above this again is the 

 inferior and inner orbitary margin, giving attachment to 

 the levator-labii superioris alasque nasi, and covered by 

 the orbicularis palpebrarum muscle. 



The malar bone forms the outer boundary of the face ; 

 and the lower jaiu, which projects forward into the chin, 

 and backward and upward into the rami and processes, the 

 inferior boundary. 



The cavities of the face are the orbits and the nose. The 

 orbits are two hollow cones with their bases in front and 

 their apex behind. The directions of their axes are back- 

 wards and inwards, and, if prolonged, they would inter- 

 sect each other over the sella turcica, forming an angle of 

 about 90 degrees. Seven bones enter into the composition 

 of each orbit. The roof is formed by the orbital processes 

 of the frontal bone and the lesser wing of the sphenoid. The 

 floor is formed by the orbital processes of the superior max- 

 illary bone and of the palate bone, together with a portion 

 of the malar. The outer wall consists of the orbital sur- 

 faces of the greater wing of the sphenoid and malar bones, 

 while the inner wall is composed of the lachrymal, the os- 

 planum of the ethmoid, and part of the sphenoid. 



Several foramina and openings communicate with the 

 orbit. Behind are the optic foramen, giving entrance to the 

 optic nerve and ophthalmic artery, and the foramen lacerum 

 superius or orbitale, or the sphenoidal fissure, transmitting 

 the third, fourth, first branch of the fifth, and the sixth 

 nerves. At the lower and outer portion of the orbit is the 

 splieno-inaxillary fissure, in which is found the superior max- 

 illary nerve and artery. There are also some small fora- 

 mina penetrating the malar bone. On the inner wall are 

 seen the anterior and posterior ethmoidal foramina the for- 

 mer giving passage to the nasal branch of the ophthalmic 

 nerve and the anterior ethmoidal artery, the latter to the pos- 

 terior ethmoidal artery. At the inner canthus is the nasal 

 duct, and in the supra-orbital margin the supra-orbital fora- 

 men. The ball of the eye with its muscles, vessels, nerves, 

 and the lachrymal gland and its ducts, are all contained 

 within the orbits. 



