184 BONES OF THE CRANIUM. 



which corresponds to the torcular Heropliili. The transverse 

 ridge has attached to it the tentorium, and is grooved for the 

 lateral sinuses. The vertical ridge has attached to its su- 

 perior part the falx cerebri, and to its inferior portion the 

 falx cerebelli. The cerebral surface of the basilar process, is 

 concave and supports the pons varolii and basilar artery. 



The foramina are seven : 5 proper and 2 common. The 

 proper are the 4 condyloid, 2 anterior and 2 posterior, and 

 the foramen magnum. The common are the 2 foramina 

 lacera posteriora. The processes are seven : 1 cuneiform, 2 

 eondyles, 2 jugular, and 2 occipital protuberances. 



This bone has four angles : a superior, which unites with 

 the parietal bones, an inferior, which is attached to the 

 sphenoid; and two lateral, which are blunt, and occupy the 

 spaces between the mastoid portion of the temporal and 

 posterior inferior angle of the parietal bones. 



The structure consists of two compact tables and an in- 

 termediate diploe. The tables are so compact and thin in 

 the fossae, as to be diaphanous. The spongy tissue prevails 

 in the processes. This bone is firm and hard, and in many 

 places thick. 



Its development is from seven points : one for the basilar 

 process, one for each condyle, and four for the superior part. 

 Ossification begins in the superior portion before it does 

 in the vertebrae, by four osseous points, two above and 

 two below the occipital protuberance, which scon unite to 

 form a single piece. At birth the occipital bone is seen in 

 four pieces, which become united to each other from the 

 fourth to the sixth year, and with the sphenoid by the 

 basilar process, about the twentieth year. 



The occipital bone is articulated with six bones: the 

 sphenoid, 2 temporal, 2 parietal and the atlas. 



Temporal Bones (Ossa Temporum, Bones of Time) 

 The situation of the temporal bones is at the side, middle 

 and inferior parts of the cranium. The form is very irreg- 

 ular, and each is divided into the squamous, mastoid and 

 petrous portions. 



The squamous, or scaly part, forms the superior divis- 



