go A MANUAL OF ANATOMY 



and (8) Vidian or pterygoid canal, the last-named being between the 

 internal pterygoid plate and the body. All these openings are 

 common to each side. 



The sphenoidal air sinuses are situated within the body, and are 

 two in number, right and left. They are separated from each other 

 by a septum, which is usually slightly bent to the left side. The 

 sinuses are — at least, after adult life — usually multilocular, and 

 they may extend backwards so as to invade the basilar process 

 of the occipital, especially in old age. Each sinus may even 

 extend slightly into the attached portion of the great wing. They 

 are lined with mucous membrane, which is continuous with that of 

 the nasal fossae, and each opens anteriorly by a small circular 

 aperture into the spheno-ethmoidal recess above and behind the 

 corresponding superior meatus. 



The sphenoidal turbinate or spongy bones (sphenoidal turbinals 

 or bones of Bertin) are situated on the anterior and inferior 

 surfaces of the body of the sphenoid, of which they form a 

 large part. In the adult they are blended with the sphenoid and 

 adjacent parts of the ethmoid and palate bones, but in early 

 life they are quite distinct. Each has the form of a three-sided, 

 hollow pyramid, the apex of which is directed backwards and down- 

 wards to the front part of the vaginal process, whilst the base is in 

 contact with the back part of the lateral mass of the ethmoid. The 

 inferior surface looks into the posterior part of the roof of the nasal 

 fossa, and it converts the spheno-palatine notch on the upper border 

 of the perpendicular plate of the palate bone into a foramen. The 

 external surface appears on the inner wall of the spheno-maxillary 

 fossa, and a portion of it is sometimes seen on the inner wall of the 

 orbit, behind the os planum of the ethmoid. The superior surface 

 is in contact with the anterior and inferior surfaces of the front part 

 of the body of the sphenoid. It is at the upper part of this surface, 

 on either side of the middle line, where the openings of the sphenoidal 

 air sinuses ultimately appear as small circular apertures. When 

 the sphenoidal spongy bones are broken away these openings are of 

 large size and irregular outline. 



The blood-supply of the bone is derived from branches of the 

 deep temporal arteries externally, the middle and small meningeal 

 internally, and the Vidian, pterygo-palatine, and spheno-palatine 

 branches of the internal maxillary, as these traverse their respective 

 passages. 



Articulations^— The sphenoid articulates with fourteen bones, as 

 follows : occipifal, two temjffbrals, two par?eta^s, frontal, ethrftoid, 

 two sphenoidal turbinates, two malars, two palates, and vomer. It 

 sometimes also articulates with the superior maxillae. 



Structure. — The body of the bone is excavated into two air 

 sinuses. 



Varieties. — (i) Middle clinoid process. (2) Carotico-clinoid foramen. 

 (3) Ossification of interclinoid ligament between anterior and posterior clinoid 

 processes. (4) The lateral margin of the dorsum sellae may present a superior 



