SUBOCCIPITAL TRIANGLE. 535 



outer part of the inferior curved line of the occipital bone for about attach- 

 an inch, as well as into the surface below it. ments; 



The muscle is covered by the complexus, and, at its insertion, by relations; 

 the obliquus superior. It lies over the posterior arch of the atlas 

 and the ligaments attached to that part of the bone, 



Action. By the action of both muscles the head will be drawn and use. 

 backwards. One rectus acting alone will rotate, as well as extend 

 the head, turning the face to the same side. 



The RECTUS CAPITIS POSTICUS MINOR (fig. 192, B) is a small fan- Rectus pos- 

 shaped muscle, lying to the inner side of the preceding. Arising tlcus imnor: 

 close to the middle line from a slight roughness on the posterior 

 arch of the atlas, it is inserted into the inner third of the inferior attach- 

 curved line of the occipital bone and an impression below this. lts ' 



This muscle is deeper than the rectus major, and lies Over the pos- relations ; 

 terior occipito-atlautal ligament. The two small recti correspond 

 to the interspinal muscles between the other vertebrae. 



Ad ion. The rectus posticus minor extends the head. an d use . 



The OBLIQUUS CAPITIS INFERIOR (fig. 192, c) is the strongest of obliquus 

 the suboccipital muscles. It arises from the spinous process of the inferior: 

 axis below the rectus posticus major, and is inserted into the lower attach- 

 and back part of the transverse process of the atlas. ments ; 



The inferior oblique is concealed by the complexus and trachelo- relations; 

 mastoid muscles, and is crossed by the great occipital nerve. 



Action. This muscle turns the face to the same side, by rotating and use. 

 the atlas on the axis. 



The OBLIQUUS CAPITIS SUPERIOR (fig. 192, D) arises from the Obliquus 

 transverse process of the atlas above the insertion of the pre- su P enor: 

 ceding muscle, and is directed upwards and inwards to be inserted attach- 

 into the outer part of the space between the curved lines of the mi 

 occipital bone. 



The origin of the muscle is beneath the trachelo-mastoid, and its relations 

 insertion beneath the complexus. In the interval between these it 

 is covered by the splenius. It lies over the vertebral artery and 

 the insertion of the rectus posticus major. 



Action. With its fellow the upper oblique will assist in carrying and use. 

 backwards the head. By the action of one muscle the head will 

 be inclined backwards, and to the same side. 



SUBOCCIPITAL TRIANGLE. This name is given to the small space Triangular 

 which is bounded below by the obliquus inferior muscle, by the tween the 

 rectus posticus major on the inner side and above, and by the muscles: 

 obliquus superior on the outer side. It is covered by the com- 

 plexus ; and its floor is formed by the neural arch of the atlas, 

 with the posterior occipito-atlantal ligament. In it are seen a small contents, 

 part of the vertebral artery, and the posterior branch of the sub- 

 occipital nerve issuing below the artery and lying upon the posterior 

 arch of the atlas. 



The contents of the sub-occipital traingle should be fully displayed 

 before the following parts are studied. 



The ROTATORES DORSI are eleven short muscular slips in the Rotatores 

 dorsal region beneath the multifidus spinae, from which they 



