MUSCLES ON POSTERIOR NECK AND BACK. 495 



triangular, having its apex below and "base above, being 

 situated to the inner side of the rectus major, and with it 

 occupying the space between the head and the first and 

 second vertebrae. It arises from the tubercle on the poste- 

 rior part of the atlas, and passes upward and outward to 

 be inserted broad into the rough surface between the infe- 

 rior transverse ridge, and foramen magnum of the occipital 

 bone. Function. To draw the head backward. 



The obliquus capitis superior arises narrow from the 

 transverse process of the atlas, and is inserted, by a broad 

 attachment to the occipital bone, behind its mastoid pro- 

 cess, function. To bend the head to one side and draw 

 it backward. 



The obliquus capitis inferior arises from the spinous pro- 

 cess of the vertebra dentata, passes upward and outward, 

 and is inserted into the extremity of the transverse process 

 of the. atlas. Function. To rotate the atlas and head upon 

 the dentata or second vertebra. 



These four little muscles form nearly an equi-lateral 

 triangle. The base Consists of the recti along the middle 

 line. The apex is the extremity of the transverse process, 

 and the sides of the triangle are the superior and inferior 

 oblique muscles. A quantity of fatty and cellular struc- 

 ture fills up this triangle, and deep in it are seen the verte- 

 bral artery, a plexus of veins, and the sub-occipital nerve. 



The semi-spinalis colli et dorsi appears as one continued 

 muscle, though it has been distinguished into two. They 

 extend from transverse to spinous processes, encircling about 

 one-half the vertebral column hence their name. They 

 are with difficulty distinguished from the multifidus spinae. 



The semi-spinales colli arise from the transverse processes 

 of the five superior dorsal vertebrae, and are inserted into 

 the spinous processes of the middle cervical vertebrae. 



The semi-spinales dorsi arise from the transverse pro- 

 cesses of the six lower dorsal vertebrae, and are inserted 

 into the spinous processes of the two lower cervical, and 

 four upper dorsal. Function. To draw the spine obliquely 

 backward. 



