THE CRANIUM. 1 33 



bone, and another along the inferior angle, adjoining the basilar 

 process of the occipital bone, and formed in part by it : they 

 are made by the superior and inferior petrous sinuses. 



The temporal bone articulates with the occipital, the parie- 

 tal, the sphenoid, and the malar. 



5. Sphenoid Bone, (Os Sphenoides, Sphenoide.) 



The sphenoid is a symmetrical, but very irregular bone, 

 placed transversely in the middle of the base of the cranium. 



It consists of a cuboidal body in the centre, of a very large 

 process called the great wing, and spreading laterally to a con- 

 siderable distance on either side of the body, and it has, also, 

 a number of angular margins and additional processes about it. 



In regard to the body of the sphenoid bone, from its upper 

 anterior part arise, one on each side, the apophyses of Ingras- 

 sias, or the little wings. These wings have a broad horizontal 

 base, and extending themselves outwardly, terminate in a sharp 

 point. Their anterior edge is serrated for articulating with 

 the os frontis : the posterior edge is smooth. Between the two 

 wings, in front, is a prominence united to the ethmoid bone. 

 The base of the wing is perforated by the foramen opticum, 

 for transmitting the optic nerve with the ophthalmic artery. 

 Below and behind this foramen, the little wing terminates in a 

 point, called the anterior clinoid process. Between the fora- 

 mina optica is a ridge of bone, sometimes called processus oli- 

 varis, and just above the ridge a groove, made by the optic 

 nerves where they unite. Behind the ridge is a depression, 

 the Sella Turcica, for containing the pituitary gland. This 

 depression is bounded behind by a very elevated transverse 

 ridge, called the posterior clinoid process. At either extremi- 

 ty of the base of the latter, a groove (sulcus caroticus) is made 

 by the carotid artery, which groove may be traced indistinctly 

 under the anterior clinoid process, where it forms a notch, and 

 sometimes a foramen. 



The posterior face of the body of the sphenoid bone, presents 

 a flat surface for articulating with the cuneiform process of the 

 occipital. Most frequently, in the adult, the bones are anchy- 

 losed at this junction. The inferior part of the body of the 

 sphenoid presents a rising, in its middle, called the sphenoidal 

 VOL. I. 12 



