446 



THE MUSCLES 



movements are tlie phrenic and those which sn})])ly certain of the muscles of the 

 neck. (5) If the head be much thrown ])ack, the two sterno-mastoids may be 

 used to increase the extension. 



Relations. — Superficially, the deep cervical fascia and integuments, the pla- 

 tysma myoides, external jugular vein, and many of the superficial branches of 

 the een'ical plexus, and the glandula? concatenatae; deeply, the rectus capitis anticus 

 major, omo-hyoid, sterno-hyoid and sterno-thyroid, the posterior belly of the 

 digastric, the splenius capitis, levator anguli scapulae, and three scalene muscles; 

 the common, external, and internal carotid and subclavian arteries, with several 



Fig. 314. — Axtekior and Lateral Cervical Muscles. 



Raphe of mylo 

 hyoid 



Stylo-hyoid 



Posterior belly of digastric 



Splenius capitis 



Sterno-mastoid 



Levator anguli scapulas 



Scalenus mediua 



Trapezius 



Scalenus posticus 



I'/V 



//' Posterior belly of 

 omo-hyoid 



\^^^^^^VX^\^^>U\^:^^^'^ 



branches of the external carotid, the internal jugular, facial, thyroid, anterior 

 jugular, and other veins; the spinal accessory and hypoglossal nerves, the cervical 

 and upper part of the l^rachial plexuses with many of their branches, the parotid 

 gland, the lateral lobe of the thyroid gland, and numerous deep cervical lymijhatic 

 glands. 



Variations. — The clavicular origin may extend farther outwards ujxm the colhir bone. Be- 

 sides its insertion into the mastoid process, this head may have an attachment to the superior 

 nuchal line, called the cleldo-occipital. An extension of the sternal head has been observed 

 arising from the co.stal cartilages as low as that of the fifth rib. Slips sometimes pass from the 

 upper j)art of the muscle to the angle of the jaw, the pharynx, the auricle, or the ui)per attach- 

 ment of the trapezius. 



