30 



BONES OF THE HEAD. 



The TABULAR PORTION on its posterior surface presents a rough prominence, 

 the external occipital protuberance, arching outwards from which, on each side, 



Fig. 26. OCCIPITAL BONE 

 FROM BELOW AND BEHIND, 

 SHOWING THE EXTERNAL 

 SURFACE. 4 



1, basilar process ; 2, con- 

 dyloid portion, the probe 

 marks the anterior condyloid 

 foramen; 3, jugular or trans- 

 verse process ; 4, external or 

 lateral angle ; 5, superior 

 angle ; 6, superior curved line ; 

 7, external or posterior occi- 

 pital protuberance ; 7, 8, ex- 

 ternal occipital crest ; 9, in- 

 ferior curved line ; 10, groove 

 and ridge connected with the 

 attachment of the superior 

 oblique muscle, and near it 

 the inferior opening of the pos- 

 terior condyloid foramen ; 11, 

 foramen magnum ; 12, arti- 

 cular condyle ; immediately 

 above it the posterior condy- 

 loid foramen. 



is the superior occipital 

 ridge or curved line,, which 

 divides the surface into two 

 parts, the upper, covered by the hairy scalp, convex and uniform ; the lower, 

 uneven and marked by the impressions of the muscles of the neck which are 



Fig. 27. OCCIPITAL BONE 

 FROM BEFORE, SHOWING THE 

 INTERNAL SURFACE. \ 



1, basilar process sawn 

 through at the place of union 

 with the sphenoid bone ; 2, 

 condyloid portion ; 3, jugular 

 or transverse process ; x , be- 

 tween 2 & 3, the sigmoid 

 groove of the lateral sinus and 

 jugular notch ; 4, external or 

 lateral angle ; 5, superior 

 angle; 1 to 3, the edge of 

 articulation with the petrous 

 bone ; 3 to 4, with the mas- 

 toid bone ; 4 to 5, with the 

 parietal bone ; 11, foramen 

 magnum; 13, internal occipi- 

 tal protuberance and groove of 

 the torcular Herophili ; 14, in- 

 ferior spine ; 15, groove of the 

 lateral sinus ; from 5 to 13, 

 groove of the superior longi- 

 tudinal sinus ; 16, cerebral 

 fossa; 17, cerebellar fossa. 



attached to it. This lower 



surface is divided into two lateral portions by a median ridge called the ex- 

 ternal occipital crest or spine, and each of these portions is again divided into 



