18 



ANATOMY. 



Mastoid Portion 6, the occipito- frontal is, sterno-cleido-mastoid, splenius 



capitis, trachelo-mastoid, digastric, and retrahens aurem. 

 Petrous Portion 3, the tensor tympani, levator palati, and stapedius. 

 Styloid Process 3, the stylo-glossus, stylo-hyoid, and stylo-pharyngeus. 



THE SPHENOID BONE. 



Describe its Position and Form. Wedged in between the bones of the 

 skull anteriorly, it resembles a bat with out-stretched wings. It is named 

 from the Greek word o<pfiv sphane, a wedge, enters into the formation of 5 

 cavities, 4 fossae, 3 fissures, and has 



A Body. 2 Pterygoid Processes. 12 Foramina. 



2 Greater Wings. 2 2 Styloid Processes. 12 pairs of Muscles. 



2 Lesser Wings. 1 6 Clinoid Processes. 12 Articulations. 



10 Points of Ossification. 3 Lesser Processes. 



Describe the Body of the Sphenoid Bone. Placed in the median line, 

 cuboid in shape, it presents on its UPPER SURFACE from before backwards, 

 the following points, viz. 



F Ethmoidal Spine? ar- 



2 ticulating with the 



ethmoid bone. 

 A Smooth Surface, 

 grooved for the ol- 

 factory nerves. 

 Optic Groove, support- 

 ing the commissure 

 of the optic nerves. 

 Olivary Process, an 

 olive - shaped emi- 

 nence behind the 

 optic groove. 



Middle Clinoid Processes, bounding the sella Turcica in front. 

 Sella Turcica^ (Turkish saddle), lodges the pituitary body and the circular 



sinus of the brain. 



Dorsum Sella (back of the saddle), grooved for the 6th nerves. 

 Posterior Clinoid Processes* for attachment of the tentorium cerebelli. 

 Grooves, laterally, for the cavernous sinus and internal carotid artery. 



THE POSTERIOR SURFACE is rough and quadrilateral : 15 it articulates with the 

 basilar process of the occipital bone, ossification being completed from the 

 1 8th to the 20th year. 



