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THE DISSECTION OF THE NECK. 



relations, More deeply seated below than above, the muscle is concealed by 



the clavicle and the clavicular part of the sterno-rnastoid : the 

 with vessels, phrenic nerve lies along its anterior surface, and the subclaviau 



vein crosses over it near the rib. Along the inner border is the 

 and nerves : internal jugular vein. Beneath it are the pleura, the subclavian 



artery, and the nerves of the brachial plexus. The attachment to 



the vertebras corresponds with the origin of the rectus capitis 



anticus major muscle, 

 use. Action. The muscle raises strongly the first rib, in consequence 



of its forward attachment. If the rib is fixed, it bends forwards 



the lower part of the neck. 



The SCALENUS MEDIUS MUSCLE (fig. 213, 2 ) is larger than the 



anterior, and extends highest of all on the vertebrae. Its origin is 



Scalenus 

 medius ; 



origin : 



Serratus magmis (first digitation). 



Tuberolo. 



FIG. 214. THE FIRST RIB, SHOWING THE UPPER SURFACE. 



insertion 



parts in 

 contact 

 with it : 



Scalenus 

 posticus : 



from the posterior tubercles of the transverse processes of all the 

 cervical vertebrae except sometimes the first or the last ; and it is 

 inserted into an impression on the upper surface of the first rib, 

 extending from the tuberosity behind to the groove for the subclavian 

 artery in front (fig. 214). 



In contact with the anterior surface are the subclavian artery 

 and the cervical nerves, together with the stern o-mastoid muscle : 

 the posterior surface rests on the posterior scalenus, and the deep, 

 lateral muscles of the back of the neck. The fibres are perforated 

 by the nerves of the rhomboid and serratus magnus muscles. 



Action. Usually it elevates the first rib. With the rib fixed, 

 the cervical part of the spine can be inclined laterally by one 

 muscle. 



The SCALENUS POSTICUS is inconsiderable in size, and appears 

 to be part of the preceding muscle. Arising from two or three of 



