426 



THE MUSCLES AND FASCIA 



Relations. By its anterior surface, with the Sterno-mastoid ; it is crossed by 

 the clavicle, the Omo-hyoid muscle, subclavian artery, and the cervical nerves. To 

 its outer side is the Levator anguli scapulae and the Scalenus posticus muscle. 



The Scalenus posticus, the smallest of the three Scaleni, arises, by two or three 

 separate tendons, from the posterior tubercles of the transverse processes of the 

 lower two or three cervical vertebrae, and, diminishing as it descends, is inserted 

 by a thin tendon into the outer surface of the second rib, behind the attachment of 

 the Serratus magnus. This is the most deeply placed of the three Scaleni, and is 

 occasionally blended with the Scalenus medius. 



Nerves. The Rectus capitis anticus major and minor and the Rectus lateralis 

 -are supplied by the first cervical nerve, and from the loop formed between it and 



SUPERIOR 



FIG. 2&5. Muscles of the neck. (From a preparation in the Museum of the Royal College of Surgeons of 

 England.) 



the second ; the Longus colli and Scaleni, by branches from the anterior divisions 

 of the lower cervical nerves (fifth, sixth, seventh, and eighth) before they form the 

 brachial plexus. The Scalenus medius also receives a filament from the deep 

 external branches of the cervical plexus. 



Actions. The Rectus anticus major and minor are the direct antagonists of the 

 muscles at the back of the neck, serving to restore the head to its natural position 

 after it has been drawn backward. These muscles also serve to flex the head, and, 



