THE CRANIUM. 129 



That part of the bone before the condyles is the cuneiform or 

 basilar process: the base of which is marked by depressions for 

 the insertion of the recti muscles, which are situated on the 

 front of the cervical vertebrae; and its fore part, which is trun- 

 cated at the end, overhangs the pharynx, and is placed against 

 the body of the sphenoid bone. The superior external part of 

 the os occipitis is uniformly convex, being covered by the oc- 

 cipito frontalis. 



The internal surface' of the os occipitis is strongly impressed 

 by ridges and depressions. On that portion of it behind the 

 great foramen, is a rectangular cross, forming at its centre a 

 large internal protuberance. The upper limb of the cross is 

 marked by a fossa for the longitudinal sinus; the two horizon- 

 tal limbs are also marked, each by its respective fossa, which 

 receives the corresponding lateral sinus. The right fossa is fre- 

 quently the largest. The inferior vertical limb of the cross has 

 attached to it the small falx of the dura mater, and is slightly 

 depressed by a small sinus. The spaces between the limbs of 

 the cross are much thinner than other parts of the bone, and 

 present broad concavities, the two superior of which receive 

 the posterior lobes of the cerebrum, and the two inferior, the 

 lobes of the cerebellum. 



The superior face of the cuneiform process is excavated, lon- 

 gitudinally, to receive the medulla oblongata. On each side of 

 the foramen magnum, a short curved fossa is observed, which 

 receives the lateral sinus just before its exit from the cranium. 



The two superior margins of the occipital bone are regularly 

 serrated. The inferior margins have each, in their centre, a 

 process termed the jugular eminence, in front of which is a 

 rounded notch, forming a part of the jugular fossa, which trans- 

 mits the internal jugular vein and the eighth pair of nerves. 

 The edge of the bone above this eminence is serrated, but be- 

 low it is rather smooth and rounded, being parallel with the 

 temporal bone, and having an imperfect adhesion to the petrous 

 part of it, before the jugular fossa. 



The occipital bone articulates above with the parietal, lateral- 

 ly with the temporal; and in front with the sphenoid. 



