NERVES OF THE NECK. 509 



The anterior jugular, called also superficial thyroid vein, 

 begins at the os-hyoides, and descends along the anterior 

 margin of the sterno-mastoideus, near the median line of 

 the neck, covered by the superficial cervical fascia, and ter- 

 minates below, either in the external jugular or subclavian 

 veins. The two anterior jugulars often connect by a trans- 

 verse branch and frequently communicate above with the 

 facial, internal, and external jugular veins. They also 

 vary much in size and return the blood from the superficial 

 parts on the front of the neck. 



The subclavian veins are continuations of the axillary, 

 anc}. are situated beneath the clavicle and subclavius mus- 

 cle. Passing over the first rib, in front of the subclavian 

 artery, and crossing the scalenus anticus muscle, they ter- 

 minate by uniting with the internal jugular, to form the 

 right and left vena innominata, which also unite to consti- 

 tute the superior vena cava. The subclavian veins receive 

 the tributary streams of the external jugular veins, the ver- 

 tebral, inferior thyroid, inferior laryngeal, internal mammary, 

 and superior intercostal though these latter frequently 

 empty into the vena innominata. 



SECTION V. 



These are the par vagum, spinal accessory, lingual, fa- 

 cial, cervical plexus and phrenic nerve, brachial plexus, 

 sympathetic nerve and its ganglia. 



The par vagum (Fig. 152) has been already fully de- 

 scribed under the head of organs of deglutition in the neck, 

 which see. 



The spinal accessory nerve, (Fig. 153,) or third division of 

 the eighth pair, called the superior respiratory nerve of Sir 

 Charles Bell, arises as low down in the neck as the fourth 

 or fifth cervical vertebra, by several filaments from the res- 

 piratory tract, between the anterior and posterior spinal 

 roots; it ascends behind the ligamentum denticulatum, tp 

 the base of the cranium, passes through the foramen mag- 



