126 



ANATOMY FOR NUKSES. 



[CHAP. X. 



I. Those from which the blood is carried to the heart by the 

 superior vena cava, viz. the veins of the head and neck and 



upper limbs, together with those of 

 the spine and a part of the walls of 

 the thorax and abdomen. In this 

 group we may include the veins of 

 the heart, which, however, pass directly 

 into the right auricle without entering 

 the superior vena cava. 



II. Those from which the blood is 

 carried to the heart by the inferior vena 

 cava ; viz. the veins of the lower limbs, 

 the lower part of the trunk, and the 

 abdominal viscera. 



1. The blood returning from the 

 head and neck flows on each side into 

 two principal veins, the external and 

 internal jugular. 



The external jugular commences near 

 the angle of the jaw by the union of 

 two smaller veins, and descends almost 

 vertically in the neck to its termination 

 in the subclavian vein. 



The internal jugular, receiving the 

 blood from the cranial cavity, descends 

 the neck close to the outer side of the 

 internal and common carotid arteries. 

 It unites at a right angle with the 

 subclavian to form the innominate vein. 1 



The blood from the upper limbs is 

 returned by a superficial and deep set 

 of veins. The superficial are much 

 larger than the deep, and take a greater 



Fia. 97. SKETCH OF THE 

 PRINCIPAL VENOUS TRUNKS. 

 I, superior vena cava; 2, in- 

 ferior vena cava; 3, right sub- 

 clavian and innominate veins; 

 4, left subclavian and innomi- 

 nate veins ; 5, 5, right and left 

 internal jugular veins; 8, right 

 azygos vein ; 10, left azygos 

 vein ; 13, 13, common iliac veins ; 

 14, 14, sacral veins. 



1 NOTE ON VENOUS CIRCULATION OF THE 

 SKULL. The blood from the skull is returned 

 from the smaller veins to the internal jugular 

 veins by channels which are not strictly veins, 

 but sinuses. These sinuses are spaces left be- 

 tween the layers of the dura mater, and are lined 

 by a continuation of the lining membrane of the 

 veins. 



