166 MAMMALIAN ANATOMY 



The surface around the foramen magnum is elevated. Above, it 

 slopes away from the nmrgin up to the curved line ; at the sides, it 

 forms the smooth, prominent condyles for articulation with the first 

 vertebra ; below, it is continuous with the external surface of the 

 basilar plate. 



Each condyle is an oval swelling, but the regular oval of its 

 outline is encroached upon at its inner back part by the concave lower 

 part of the margin of the foramen magnum. Its long axis is directed 

 outward and upward in such manner that, while the lower end is on 

 the margin of the foramen, the upper end lies to the outside of it. 

 The condyle is slightly convex from side to side, and strongly convex 

 from above downward. The highest part of the convexity is nearer 

 the upper part than the lower, and is on a line which crosses the long 

 axis obliquely, passing from about the middle of the inner margin to 

 near the tip of the outer margin. The condyle is separated by a 

 depression from the tubercle above, and at the side there is a well- 

 marked constriction or neck. 



Beyond the outer side of the condyle is a deep excavation, which 

 begins above the condyle at the side of the central elevated sloping 

 portion of the external surface of the bone and stops at the base of 

 the paroccipital process. It is indistinctly divided by a transverse 

 ridge at a level with the tip of the condyle into two parts, of which 

 the upper is the smaller. These fossa3 lodge the obliquus capitis 

 superior muscle. 



At the top of the external surface, below and almost in contact 

 with the superior curved line, is a rough, narrow area, which joins 

 the superior curved line on each side half-way down the lateral border. 

 It affords attachment to several muscles. 



From the middle point of the superior curved line a ridge, more or 

 less marked, runs down toward the foramen magnum. This ridge is 

 called the occipital crest, and varies much in development. In well- 

 marked skulls, on each side of this crest, midway between the superior 

 curved line and the foramen magnum is an obscure inferior curved line. 



The jugular processes are the prominent inferior angles. Each 

 process has a posterior or external surface and an anterior or internal 

 surface. The external surface (Fig. 110) is gently convex in all 

 directions, and its plane forms an angle with the plane of the general 

 external surface and faces slightly upward as well as backward. The 



