SPHENOID BONE. 41 



foramina are two sharp tubercles, the anterior clinoid processes, 

 which are the inner termination of the lesser wings. Beneath these 

 processes, on the sides of 



the olivary process, are Fi - 16 -* 



two depressions! for the 

 last turn of the internal 

 carotid arteries. Behind 

 the olivary process, is the 

 sella Turcica, the deep 

 fossa which lodges the 

 pituitary gland and cir- 

 cular sinus ; behind and 

 somewhat overhanging 

 the sella Turcica, is a 

 broad rough plate, bound- 

 ed at each angle by a tubercle, the posterior clinoid processes ; and 

 behind this plate an inclining surface, which is continuous with the 

 basilar process of the occipital bone. On either side of the sella 

 Turcica is a broad groove (carotid) which lodges the internal 

 carotid artery, the cavernous sinus, and its nerves. Immediately 

 external to this groove, at the junction of the greater wings with 

 the body, are four foramina: the first is a broad interval, the spfie- 

 noidal fissure, which separates the greater and lesser wings, and 

 transmits the third, fourth, the three branches of the ophthalmic 

 division of the fifth and the sixth nerves, and the ophthalmic vein. 

 Behind and beneath this fissure is the foramen rotundum for the 

 superior maxillary nerve ; and still farther back, in the base of the 

 spinous process, the foramen ovale for the inferior maxillary nerve, 

 arteria ineningea parva, and nervus petrosus superficialis minor. 

 Behind the foramen ovale, near the apex of the spinous process, is 

 the foramen spinosum for the arteria meningea magna. 



* The superior or cerebral surface of the sphenoid bone. 1. The processus olivaris. 

 2. The elhmoidal spine. 3. The lesser wing of the left side. 4. The cerebral sur- 

 face of the greater wing of the same side. 5. The spinous process. 6. The extremity 

 of the pterygoid process of the same side, projecting downwards from the under sur- 

 face of the body of the bone. 7. The foramen opticum. 8. The anterior clinoid pro- 

 cess. 9. The groove by the side of the sella Turcica ; for lodging the internal carotid 

 artery, cavernous plexus, cavernous sinus, and orbital nerves. 10. The sella Turcica. 

 11. The posterior boundary of the sella Turcica; its projecting angles are the pos 

 terior clinoid processes. 12. The basilar portion of the bone. 13. Part of the sphe- 

 noidal fissure. 14. The foramen rotundum. 15. The foramen ovale. 16. The fora- 

 men spinosum. 17. The angular interval which receives the apex of the petrous portion 

 of the temporal bone. The posterior extremity of the Vidian canal terminates at this 

 angle. 18. The spine of the spinous process ; it affords attachment to the internal 

 lateral ligament of the lower jaw. 19. The border of the greater wing and spinous 

 process which articulates with the anterior part of the squamous portion of the tem- 

 poral bone. 20. The internal border of the spinous process, which assists in the 

 formation of the foramen lacerum basis cranii. 21. That portion of the greater ala 

 which articulates with the anterior inferior angle of the parietal bone. 22. The por- 

 tion of the greater ala which articulates with the orbital process of the frontal bone. 



t These depressions are occasionally, as in a skull before me, converted into fora- 

 mina by the extension of a short bony pillar from the anterior clinoid process to the 

 body of the sphenoid. 



6 



