82 OS SPHENOIDES. 



immediately before them are the optic foramina, which pass 

 obliquely through the wings into the orbit of the eye, and 

 transmit on each side the optic nerve and a small artery. 



Behind the optic foramen is a notch and sometimes a foramen, 

 made by the carotid artery. When the notch is converted into 

 a foramen, it is by a small bony pillar being extended from the 

 anterior clinoid process, to the body of the sphenoid. A groove 

 made by the optic nerves, is cften seen extending across the 

 body of the bone, from one of the optic foramina to the other. 

 Behind it is a depression, which occupies the greatest part of this 

 surface of the bone, in which the pituitary gland is lodged ; the 

 back part of this depression is bounded by a transverse emi- 

 nence, called the posterior clinoid process. These three pro- 

 cesses are called clinoid from their supposed resemblance to the 

 supporters of a bed ; and the depression for the pituitary gland 

 is called sella turcica from its resemblance to the saddle used by 

 the Turks. 



On each side of the posterior clinoid process is a groove in 

 the body of the bone, made by the carotid artery as it passes 

 from the foramen caroticum of the temporal bone. The posterior 

 surface of the body of the sphenoides is rough, for articulation 

 with the truncated end of the cuneiform process of the os 

 occipitis. 



On the anterior and inferior surfaces is a spine, called the 

 azygos process, or rostrum which is received into the base of 

 the vomer, and extends forward until it meets the nasal plate of 

 the ethmoid bone ; on each side of this spine, in the anterior 

 surface, are the orifices of the sphenoidal cells. Those orifices 

 appear very differently in different bones ; in some very perfect 

 specimens, they are irregularly oval, being closed below and 

 on their external sides, by the processes of the ossa palati, and 

 above by the triangular plates, as they have been called, of 

 the ethmoid bone. The cells or sinuses, to which these 

 orifices lead, occupy the body of the sphenoidal bone ; they are 

 divided by a partition, and each of them has a communication 

 with the cavity of the nose on its respective side, by the orifice 

 above described. The sinuses do not exist during infancy ; 

 they increase in the progress of life, and are very large in old age. 



