THE HEAD AND NECK 



"37 



Insertio7i. — The upper surface of the first rib from the groove for 

 the subclavian artery backwards to the tubercle. 



Nerve-supply. — ^The anterior primary divisions of cervical ner\-es 

 from the third to the eighth inclusive. 



The muscle is directed downwards and out\vards. 



Action. — (i) To fix the first rib in ordinary inspiration, cuid (2) to 

 flex the neck to one side. 



Rectus Capitis Anticus Minor 



Rectus Lateralis ^ 



Basilar Process of Occipital Bone 



^ Vertebral Artery 

 ,' (third part) 



Rectus Capitis Anticus 

 Major 



-Longus Colli (upper oblique part) 

 Vertebral Artery (second part) 



Longus Coili (vertical part) 



—Vertebral Artery (first part) 



I r fa!f\L Longus Colli (lower oblique 



Scalene oi Lisfranc's Tubercle 



Fig. 465. — The Right Prevertebral Muscles. 

 (The Vertebral Artery is also shown). 



Relations — Anterior. — ^The cervical plexus, the nerve-roots of 

 the brachial plexus, except the first thoracic, and the second and 

 third parts of the subclavian artery. Posterior. — ^The levator anguli 

 scapulae and scalenus posticus muscles. 



The scalenus medius is pierced by the following nerves : (i) the 

 nerve to the rhomboids, which passes in a backward direction ; and 

 (2) the upper and middle roots of the posterior thoracic nerve, or 

 external respiratory nerve of Bell. These two roots usually emerge 



72 



