22O 



Anatomy of Skeleton 



The upper surface of the body presents a deep hollow open at the side, the pituitary 



fossa, for lodging the pituitary gland and its surrounding vascular plexus ; in front of 



this the olivary eminence separates it from the optic groove, which runs into the optic 



foramen at each side. In front of the groove the flatter jugum sphenoidale stands at 



a higher level than the rest of the body and is continued laterally into the lesser wings. 



The optic chiasma is attached to the front of the infundibulum of the pituitary, 



and is therefore raised above the level of the bone and does not lie in the optic groove, 



but the optic nerves run from it into the optic foramina accompanied by the ophthalmic 



arteries. The pituitary fossa is roofed in by the diaphragma sellce, a curtain of dura 



mater that is pierced centrally by the stalk of the gland. The diaphragm (Fig. 181) 



is attached to the front and back margins of the fossa, and at the sides to the clinoid 



processes and interclinoid ligaments : the an 'erior clinoid process is a thick angular 



projection from the base of the small 

 wing towards the fossa, and the posterior 

 process is the prominent upper and 

 lateral angle of the dorsum settee that 

 overhangs the back of the fossa. The 

 middle clinoid process, if present, is a 

 low point of bone situated between and 

 below the other two at the side of the 

 fossa. Interclinoid ligaments connect 

 these processes. 



At the sides, where it slopes down to 

 be continuous with the great wings, the 

 body supports the cavernous sinus on 

 each side (Fig. 182), and the system of 

 venous spaces (known as the circular 

 sinus) that surrounds the pituitary body 

 joins the two cavernous sinuses. The 

 internal carotid artery reaches the bone 

 here, deep to the s nus, from the foramen 

 lacerum (see Complete Base), and runs 

 along it in the carotid groove, to turn 

 in under the overhanging anterior clinoid 

 process and then up to the inner side of 



the process behind the optic nerve ; here it gives its ophthahrrc branch. Thus the artery 

 passes in front of the ligamentous connection between the anterior and middle clinoid 

 processes, which may be ossified, so that there may be foramina at each s : de of the 

 upper surface of the body, as shown in Fig. 180, for the optic nerve, the carotid 

 artery, and the circular sinus. 



The lower surface of the body has a thick, wedge-shaped bar running along its front 

 part, supporting the septum between the air sinuses above and ending in front in the 

 prominent rostrum : the hinder end of this bar of bone is continuous with the rest of the 

 body and is partly overlapped by the vaginal processes that turn in from the internal 

 pterygoid plates. This aspect of the body, as can be seen in the skull, carries the 

 vomer, and the two alse of that bone open out below the sphenoidal body and fit in 

 under cover of the vaginal processes. Behind this region the under surface is lined 

 by mucous membrane of the roof of the naso-pharynx. 



On each side the body is continuous with the great wing : the carotid groove 

 commences on the back of this junction, and here there is a projection on the outer 



FIG. 1 80. A specimen in which the ligamentons 

 bands joining the three clinoid processes have 

 ossified, with the result that foramina exist 

 which are not present with bony boundaries 

 in the sphenoid as usually seen. The carotid 

 passed through the arterial foramen and the 

 circular sinus through the venous foramen. 

 A carotid foramen is not uncommon ; the 

 double structure is more rare. 



