THE DISSECTION OF THE BACK 



179 



posterior major forms its upper and medial boundary ; 

 (2) the obliquus inferior limits it below; and (3) the obliquus 

 superior bounds it above and to the lateral side. Its 

 floor consists of two structures viz. the posterior arch of 

 the atlas and the thin posterior atlanto-occipital membrane. 



Occipitali 



Sterno-mastoid 



Meningeal branch _gj 

 of occipital artery " 



Occipital artery ~1 



Spl 



lenius capitis ~~f 



Vertebral artery 

 Digastric post, belly - -~ 



Sterno-mastoid 

 Descending branch of 

 occipital artery 



Levator scapulae 



Splenius cervicis 

 Longissimus capitis 



Occipital artery 



Great occipital nerve 



Trapezius 

 Semispinalis capitis 

 (O.T. complexus) 



Superior oblique 

 Great occipital nerve 



Rectus cap. post, minor 



Rectus cap. post, major 

 Edge of occ.-atlantal merr 

 Post. br. of sub-occipital n< 

 Post, arch of atlas 



Spine of epistropheus 

 Inferior oblique 



Semispinalis cervicis 



Trapezius 



Semispinalis capitis 

 (O.T. complexus) 



Splenius capitis 



FIG. 73. Dissection of the Sub-occipital Region. Note that in this specimen 

 the occipital artery is superficial to the longissimus capitis muscle. 



It contains a portion of the vertebral artery and the posterior 

 branch of the sub-occipital or first cervical nerve. 



Dissection. Before cleaning the muscles bounding the triangle, the 



posterior branch of the sub-occipital nerve must be secured. This can 



best be done by tracing into the space the minute twig which it has been 



seen to give to the deep surface of the semispinalis capitis, or, if this has 



II 12 a 



