40 y/// 



orbital hiatus, b, the sidtgphenoidal, or ptcryijoid process, & lon^ emii 

 llatti-ned tin both sides, inclining downwards, articulating \\itli tin; palate 

 :iinl pterygoid bones, ami traversed at its base by the vidian canal; c, a 

 little bound and above this eminence, the superior orifice of tin 

 s/ilifiKiiilnl fiimiiit-n. a large canal which bifurcates interiorly ; <l, more in 

 front, the arhilnl liiulut, a kind of vestibule into which open in common the 

 principal branch of the subsphcnoidal canal, the three, snpergphenoida] 

 anals. the vidian and optic canals, and tho orbital opening: this hiatus is 

 surmounted by a thin and sharp bony plate, above which opens the small'--! 

 branch of tho subsphenoidal foramen; e, altogether without the hiatus is 

 lemarked a smooth surface belonging to the wing of the sphenoid, and 

 which concurs to form the orbital cavity. 



The interAal face is concave from side to side. It shows: 1, On the 

 median lino, and from before to behind, a small projection united to the 

 crista-gnUi ; the optic fossa, elongated transversely in the form of a shuttle, 

 and presenting at the bottom, and on each side, the superior orifice of the 

 optic foramen, a cylindrical canal directed obliquely downwards, forwards, 

 and outwards, to reach tho orbital hiatus ; the supersphenoidal or jtitnitnri/ 

 fossa, also named the Bella turcica, a slight depression, limited behind by a 

 scarcely noticeable transverse projection separating it from the superior 

 channel of the basilar process; 2, On the sides, and in front, the internal 

 sin-face of the wings, depressed by very superficial digital impressions ; 

 more behind and outwards, a fossa, elongated from before to behind, which 

 lodges tho mastoid lobule of the brain ; between this fossa and the sella 

 turcica, two vertical fissures : an internal, named the cavernous sinus, and an 

 external, wider and deeper, for the passage of a large nervous branch. 

 These two fissures open below, near the junction of the three super- 

 sphcnoidal canals. Two of these, which are very wide, arc placed one before 

 the other, and separated only by a slight partition. The superior of these 

 constitutes tho great sphenoidal fissure ; the other, the lower, is the fornnini 

 rotundum, and opens into the orbital hiatus. The third, very small, is situated 

 outside the great anterior canal, opens above the optic foramen, within the 

 bony mass surmounting the hiatus, and sometimes on the free margin of 

 this lamina. 



Borders. The superior is a little concave, and shows, in its middle, the 

 superior extremity of the body, mammillated and articulated with the 

 summit of the basilar process ; on each side, two notches which circumscribe 

 below the occipito-spheno-temporal hiatus (foramina lacera basis cm nil >. 

 The internal notch is the narrowest, and from its affording a passage for tho 

 internal carotid artery, is called the carotid notch ; it is continued on the 

 external face of the bone by a smooth excavation to which Rigot has given 

 the name of carotid fossa. Tho external is also prolonged on the exterior 

 surface cf tho sphenoid by a short and wide fissure ; it lodges the inferior 

 maxillary nerve. Outside this is another very narrow notch, intended for 

 the passage of tho middle meningeal artery. The fibro-cartilaginous sub- 

 stance that partly fills the occipito-spheno-temporal hiatus, transforms these 

 notches into foramina, the first of which is named the carotid canal, tho 

 second, the foramen ovale, and the third, tho foramen spinosum. The in/ 

 border, also concave, is likewise divided into three portions, a middle and 

 two lateral. The first is thick, and formed by the inferior extremity of tho 

 taidy ; it is excavated by two largo cavities belonging to the sphenoidal sinus. 

 These cavities are s--|iaratrd from one another by a vertical osseous plate, 

 often perforated, which, at an early period, is fused with the perpendicular 





