THE SPHENOID BONE. 



19 



FIG. 



THE ANTERIOR SURFACE is nearly vertical, and presents the 



Lamella, in the median line, articulating with the perpendicular plate of 



the ethmoid bone, and forming part of the nasal septum. 

 Opening of the Sphenoidal Sinuses, , e or cavities in the body of the bone 



which exist in adults, not in children. 

 Sphenoidal Turbinated Bones (pyramids of Wistar), which partially close 



the sinuses, and articulate with the ethmoid and palate bones. 

 THE INFERIOR SURFACE helps to form the nasal fossae, and presents the 

 Rostrum fl which articulates with a groove on the vomer. 

 Vaginal Processes, I on each side of the rostrum. 

 Ptery go-palatine Grooves, which, with the sphenoidal processes of the palate 



bones, form the pterygo-palatine canals, for the transmission of the pterygo- 



palatine arteries and nerves. 



Describe the Greater Wings of the Sphenoid. Each wing, on its 

 SUPERIOR SURFACE, presents the following points, viz. 

 Foramen Rotun- 



dum? for the 



superior max- 

 illary division 



of the 5th. 

 Foramen Ovate? 



for the inferior 



maxillary divi- 

 sion of the 5th 



n erve , the 



small petrosal 



nerve, and the 



small me n - 



ingeal artery. 

 Foramen Vesalii, transmitting a small vein. 

 Foramen Spinosvmj* transmitting the middle meningeal artery. 

 THE ANTERIOR SURFACE assists in forming the external wall of the orbit, the 

 spheno-maxillary and sphenoidal fissures. It articulates with the frontal and 

 malar bones, and presents a 



Notch, transmitting a branch of the ophthalmic artery. 



Spine, for part of the lower head of the external rectus muscle. 



External Orbital Foramina, transmitting arterial branches. 

 THE EXTERNAL SURFACE presents the following points, 



Pterygoid Ridge, dividing the temporal fossa from the zygomatic. 



Spine of the Sphenoid^ to which are attached the internal laternal ligament 



of the lower jaw, and the laxator tympani muscle. 



