THE ANTERIOR PART OF THE NECK 157 



transverse process of the seventh cervical vertebra and the 

 neck of the first rib. It has been already noticed in the 

 dissection of the back of the neck (p. 67). 



The deep cervical vein is a large vessel. It joins the 

 vertebral vein. 



Arteria Intercostalis Suprema. The superior intercostal 

 artery turns downwards, anterior to the neck of the first rib, 

 between the first thoracic nerve and the first thoracic ganglion 

 of the sympathetic trunk. It gives a posterior intercostal 

 branch to the first space and ends as the posterior intercostal 

 artery of the second space (Fig. 56). 



Vena Subclavia. The subclavian vein is the continuation 

 of the axillary vein into the root of the neck. It begins 

 at the outer border of the first rib, and arches medially 

 across the anterior surface of the lower end of the scalenus 

 anterior. At the medial margin of that muscle, and posterior 

 to the sternal end of the clavicle, it unites with the internal 

 jugular vein to form the innominate vein. In connection with 

 the subclavian vein note: (i) that the arch which it forms 

 is not so pronounced as the arch of the corresponding 

 artery; (2) that throughout its whole course it lies at a 

 lower level, and upon a plane anterior to the artery; and 

 (3) that it is separated from the artery by the scalenus 

 anterior and the phrenic nerve. In the whole of its course 

 the vein lies posterior to the clavicle. 



The sheath of the subclavian vein is attached to the posterior surface of 

 the costo-coracoid membrane. The relation is of some practical importance ; 

 for, on account of it, a forward movement of the clavicle drags upon the 

 vein, and in cases where the vessel is wounded there is always a danger of 

 air being sucked into the vein by such a movement. 



The tributary of the subclavian vein is the external jugular 

 vein, which joins it at the lateral margin of the scalenus 

 anterior. 



Ductus Thoracicus et Ductus Lymphaticus Dexter. The 

 thoracic duct is the vessel by means of which the chyle, and 

 the lymph derived from by far the greater part of the body, 

 are poured into the venous system on the left side (p. 147). 

 Its terminal or cervical portion is displayed in the dissection of 

 the neck. It is a small, thin-walled vessel, frequently mistaken 

 for a vein, which enters the root of the neck at the left 

 margin of the oesophagus. It is there that it should be 

 sought for. At the level of the seventh cervical vertebra it 



