70 SPHENOID BONE. 



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 meningea 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 medea. 



Upon the antero-inferior surface of the sphenoid is a long flattened 

 spine or crest, the superior part of which, crista sphenoidalis, articulates 

 with the central lamella of the ethmoid, while the inferior part longer and 

 sharper, the rostrum sphenoidale^ is intended to be inserted into the sheath 

 formed by the upper border of the vomer. On either side of the crista 

 sphenoid alis is an irregular opening leading into the sphenoidal cells. 

 The sphenoidal cells, which are absent in the young subject, are divided 

 by a median septum which is continuous with the crista, and are partially 

 closed by two thin plates of bone (frequently broken away), the sphenoidal 

 spongy bones. On each side of the sphenoidal cells are the outlets of the 



optic foramina, sphenoidal fissures, 

 and foramina rotunda, the lesser 

 and greater wings ; and, below, the 

 pterygoid processes. Upon the un- 

 der surface of the body are two thin 

 plates of bone (processus vaginales) 

 proceeding from the base of the 

 pterygoid process at each side, and 

 intended for articulation with the 

 borders of the vomer. On each of 

 these plates, close to the root of 

 the pterygoid process, is a groove 



(sometimes a complete canal) converted into a canal by the palate bone, 

 the ptery go-palatine canal for the pterygo-palatine artery ; and traversing 

 the roots of the pterygoid processes at their union with the body of the 



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; the two 

 tubercles in front of the figure are the middle clinoid processes. 11. The posterior 

 boundary of the sella turcica; its projecting angles are the posterior clinoid processes. 

 12. The basilar portion of the bone. 13. Part of the sphenoidal fissure. 14. The fora- 

 men rotundum. 15. The foramen ovale. 16. The foramen spinosum. 17. The angu- 

 lar 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 

 spinons 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 temporal 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 portion of the greater ala which articulates with 

 the orbital process of the frontal bone. 



* The antero-inferior view of the sphenoid bone. 1. The ethmoid spine. 2. Thft 

 rostrum. 3. The sphenoidal spongy bone, partly closing the left opening of the sphe- 

 noidal cells. 4. The lesser wing. 5. The foramen opticum, piercing the base of the 

 lesser wing. 6. The sphenoidal fissure. 7. The foramen rotundum. 8. The orbital 

 surface of the greater wing. 9. Its temporal surface. 10. The pterygoid ridge. 11. 

 The pterygo-palatine canal. 12. The foramen of entrance to the Vidian canal. 13. 

 The internal pterygoid plate. 14. The hamular process. 15. The external pterygoid 

 plate. 16 The foramen spinosum 17. The foramen ovale. 18. The extremity ot 

 tbe sDinous process of the sphenoid. 



