1914.] NATURAL SCIENCES OF PHILADELPHIA. 417 



it returns blood to the anterior vena cava; it is drawn too large in 

 the figure. 



Just cephalad to the vertebral and internal Aiammary, the internal 

 jugular, j, enters the precava. The internal jugular may be followed 

 directly forward, close to the side of the trachea and oesophagus, 

 from which it receives numerous branches. Near its point of entrance 

 to, or rather exit from, the skull, it anastomoses, by two or three 

 short branches, with the external jugular, ej, to be described later. 

 Its distribution in the cranial cavity could not be determined in the 

 available material. At the point of entry of the internal jugular 

 the precava passes laterad for a short distance and then divides into 

 two more or less equal branches, the above-mentioned external 

 jugular, ej, and the subclavian, s, of which the latter will first be 

 described. 



The subclavian, s, of course, returns blood from the regions of the 

 shoulder and arm. On reaching the body wall, where it might be 

 called the axillary, ax, it receives, on its posterior side, a large thoracic 

 vein, t, which returns blood from the thorax, shoulder, and skin. 

 The thoracic receives a branch from the posterior surface of the 

 arm, which might be called the postbrachial, pb; this postbrachial 

 may be traced, as a rather small vessel, to the hand; at the elbow 

 it is connected, by one or more small branches, with the brachial. 



Just distal to the thoracic the axillary vein receives two fairly 

 large vessels, the subscapulars, sc, that return blood from the shoulder 

 and upper arm. After receiving the subscapulars, the axillary may 

 be followed into the upper arm as the brachial, br. As has been said, 

 the brachial and postbrachial anastomose near the elbow, and in this 

 region the former receives a small vessel that extends parallel to it 

 from the manus. 



In the forearm the brachial may be called the radial, fig. 2, A, ra; 

 on the back of the manus the radial receives branches from the various 

 digits and from a rather complex plexus of vessels in the carpal 

 region. 



The external jugular, fig. 2, ej, after separating from the subclavian, 

 may be traced cephalad, close beneath the skin, to the base of the 

 skull, where it is connected with the internal jugular by short 

 branches, as has already been noted. It receives several small 

 branches from the skin and muscles of the neck and shoulder 

 regions. At the region of its anastomosis with the internal jugular 

 it receives a large branch, the muscular, ms, from the massive muscle 

 at the angle of the jaw and from the skin of that region. 



