320 THE CIRCULATORY SYSTEM. 



vein comes from the head and face. It is formed by the junc- 

 tion of the anterior {y\g. 131, c) and posterior {b) facial veins 

 near the ventral border of the sternomastoid muscle. It passes 

 thence obliquely across the sternomastoid to tlie triangular 

 interval between it and the clavotrapezius. In the interval 

 it receives a small branch which accompanies the branch of 

 the transversa scapulae artery to the clavobrachialis muscle, 

 receives next the common trunk of the vena cephalica and 

 transversa scapuLx, and opposite the cranial end of the 

 manubrium receives the internal jugular vein (Fig. 129, /). 

 It then unites with the subclavian to form the innominate 

 vein. Near the point where it receives the internal jugular the 

 external jugular vein receives the thoracic duct (Fig. 118, 5). 



Branches of the external jugular: 



a. V. transversa scapulae. — This follows the course of the 

 artery of the same name. One of its branches receives one of 

 the two terminal divisions of the vena cephalica (q. v.). In 

 many cases veins which correspond to branches of the trans- 

 versa scapulae artery enter the external jugular separately (as 

 shown in Fig. 1 18, x and j'). 



Ik V. cervicalis ascendens. — A small branch which follows 

 the corresponding branch of the thyrocervical axis. 



c. V. jugularis interna (Fig. 118, 2; Fig. 119, page 284). 

 — The internal jugular vein varies much in size and in the 

 place where it joins the external jugular. The point of junction 

 is usually at about the level of the first rib, but may be much 

 farther craniad. It arises on the ventral side of the basal por- 

 tion of the occipital by the junction of a number of veins which 

 are described below. The internal jugular passes caudad in 

 the neck region at the side of the trachea, in company with the 

 common carotid artery and the vagus and sympathetic nerves. 

 In this region it receives branches which accompany the 

 branches of the common carotid artery. 



The veins which by their union form the internal jugular 

 vein are the following: 



(i) One or two veins from the venous sinuses of the brain, 

 leaving the cranial cavity by the jugular foramen. These are 

 described in the account of the veins of the brain. 



