32 THE BONES OF THE HEAD. 



surface into two parts, an upper and a lower. The protuberance varies greatly in 

 its development in different skulls ; when well marked it can be readily felt beneath 

 the skin at the back cf the head. A little above the superior curved line there may 

 generally be seen the less distinct highest curved line l ; and between the two is a 

 narrow semilunar area in which the bone is denser and smoother than either above 

 or below. The part of the surface above this is regularly convex, and is covered by 

 the hairy scalp. The lower part is more uneven : it is divided into two lateral 

 portions by a median ridge called the external occipital crest; and each of these is 



XT.OCC.PROT. 



HIGHEST CURVED UNE 



SUP. CURVED LINE 



IMF. CURVED LINE 



POST.COND.FOR. 



PHARYNC. TUB. 



BASILAR PROC. 



Fig. 32. OCCIPITAL BONE, FROM BELCW. (Drawn oy D. Gunn.) f 

 On the left side a probe is passed through the anterior condylar foramen. 



again divided into an tipper and a lower surface by the inferior curved line, which 

 can be followed outwards to the extremity of the jugular process. The curved lines 

 and the areas thus marked out give attachment to the numerous muscles of the back 

 of the neck. 



Along 1 the highest curved line the epicranial aponeurosis is fixed to the bone. To the 

 upper curved line are attached, internally the trapezius. and externally parts of the occipitalis, 

 sterno-cleido-mastoid. and splenius capitis muscles. Below the upper line is a large impression 

 for the complexus ; and more externally, immediately above the outer part of the lower line, 

 is a smaller mark where the obliquus capitis superior is inserted. The inferior curved line 

 forms the upper limit of two impressions, the inner one for the rectus capitis posticus minor, 

 and the outer one for the rectus posticus major. To the lower part of the protuberance and 

 the external occipital crest the ligamentum nuchas is attached. 



The deep surface of the bone is marked by two smooth ridges which cross one 

 another, one extending from the upper angle to the foramen magnum, and the other 

 transversely between the two lateral angles ; at the point of intersection of these 



1 F. Merkel, " Die Linea nuchse snprerca. " Leipzig, 1871. 



