THE ENTIRE SKULL 469 



The space between the two bullse comprises the middle third of the 

 width of the surface, aud is slightly narrower in front than behind. 

 It is twice as long as wide. It is bounded laterally by the inner edges 

 of the bullse and of the jugular foramina. Behind an imaginary 

 transverse line joining the paroccipital processes, it is expanded on 

 each side into the occipital condyles, between which is the deeply 

 eniarginated lower border of the foramen magnum. The anterior 

 point on this border is called the basion, and is used as a fixed point 

 in cephalic measurements. The surface between the bullre is partly 

 on the basisphenoid and partly on the basioccipital, the dividing 

 transverse suture crossing in front of the middle. It is, in general, 

 slightly convex transversely, but on the anterior half or more the 

 median line is depressed, and on each side is inserted the rectus capitis 

 anticus major muscle. The posterior half or less of this space is 

 prominent in the middle line and excavated on each side into fossae 

 for the insertion of the rectus capitis anticus minor muscle. When 

 the bulla is removed, its points of attachment to the base of the skull 

 proper are seen ; they are in front, on each side of the Eustachian 

 groove and behind the postglenoid process, and behind, just in front 

 of the stylo-mastoid foramen. The area covered by the bulla is mainly 

 the roof of the tympanum, but the large, crescentic posterior fossa, 

 which faces inward, forward, and upward and is formed by the front 

 surface of the paroccipital process and the inner surface of the mastoid 

 process, receives the rounded posterior end of the bulla. 



SIDE ASPECT OF THE SKULL. 



The lateral surface of the skull (Fig. 387) comprises the lateral 

 surfaces of the face and of the cranium. The under jaw forms the 

 lower part of the face, but for convenience should be removed. It 

 will be also found convenient in studying the lateral surface to hold 

 the skull in such a manner that with the surface toward the student 

 the lower border of the base shall be horizontal and the anterior end 

 point to the left. When thus viewed from the side it is seen to be 

 long and low, the greatest height being only three-eighths of the 

 greatest length. The lower outline appears to be straight, except for 

 the anterior irregularities produced by the teeth, the middle pro- 

 jections of the hamular process, and the posterior swelling mark- 

 ing the lower outline of the bulla. The lower outline as a whole is, 



