324 



HEAD AND NECK 



slips from the transverse processes of a corresponding number 

 of the lower cervical vertebrae in common with the scalenus 

 medius. It is inserted into the upper border of the second 

 rib, immediately anterior to the insertion of the levator 

 costae. 



The scalene muscles are supplied by twigs from the 

 anterior branches of the cervical nerves^ particularly the lower 

 four. 



Serratus posterior 

 superior (insertion) 



Scalenus posterior 

 (insertion) 



Scalenus medius (insertion) 



Serratus anterior (origin) 



Serratus anterior 

 (origin) 



Scalenus anterior (insertion) 



Subclavius 

 (origin) 



Pectoralis minor (occasional origin) 



FIG. 128. Muscle- Attachments to the Superior Surface of the 

 First Rib, and the Outer Surface of the Second Rib. 



A, First rib ; B, Second rib. 



Dissection. The little muscle termed the rectus capitis lateralis should 

 now be cleaned, and its attachments defined. It lies in the interval 

 between the transverse process of the atlas and the jugular process of the 

 occipital bone, posterior to the commencement of the internal jugular 

 vein. The anterior branch of the first cervical nerve will be seen emerging 

 from under cover of its medial margin. 



