696 THE VEINS. 



the latter to the entrance of the chest, and joining the confluent of the jugulars 

 to constitute, with these two vessels, the inferior vena cava (Fig. 389, 18). 



In studying, from their origin to their termination, the numerous branches 

 which concur in the formation of this venous trunk, we recognize : — 



1. That they form in the foot a very rich network, from which proceed the 

 digital reins, satellite vessels of the homonymous arteries. 



2. That to these digital veins, which are united in an arch above the 

 sesamoids, succeed three metacarpal branches, or collaterals of the cannon — two 

 superjjcials, placed on each side of the flexor tendons, and a deep vein, situated 

 underneath the suspensory ligament, along with the interosseous arteries. 



3. That the metacarpal veins also open into each other, in the superior and 

 posterior region of the carpus, to form, on again separating, two groups of anti- 

 hrachial veins : one group comprising the idnar and the posterior or interned 

 radials, which accompany the arteries of the same name ; the other, constituted 

 by a single subcutaneous branch — the median veiii — which receives at its superior 

 extremity the anterior superficial radial vein. 



4. That at the ulnar articulation, these two groups of antibrachial veins join 

 the satellite vessel of the anterior radial artery, and communicate by a very 

 complicated system of anastomoses, from which results a principal trunk — the 

 humeral rein. 



0. That the humercd vein, after receiving on its course several muscular 

 branches and the subcutaneous thoracic vein, unites near the shoulder- joint with 

 the brachial or subscapular trunk, to form the axillary vein. 



We will study all these branches in the inverse order of their enumeration. 



1. Brachial oe Subscapular Vein. 



A very considerable vessel, the arrangement of which resembles that of the 

 subscapular artery, though presenting some special peculiarities which do not 

 merit much attention ; for example, it most frequently receives the satellite vein 

 of the prehumeral artery. 



2. Humeral Vein. 



Placed behind and to the inner side of the humeral artery, this vessel com- 

 mences above the articulation of the elbow, being formed at this point by the 

 anastomosing system of veins from the forearm, and terminates below the shoulder- 

 joint in opening into the subscapular vein. 



Independently of the subcutaneous thoracic vein, which will be studied in 

 a special manner, the humeral vein receives on its way several collateral satellites 

 of the branches emanating from the humeral artery. One of these, the epicondy- 

 loid, is only a continuation of the ulnar vein. 



Very often we find a second humeral vein in the deep region of the arm ; 

 this is an accessory vessel, parallel to the preceding, and situated opposite it, in 

 front of the artery. 



3. Subcutaneous Thoracic or Spur Vein. 



This vein, which is important to know, as bleeding is sometimes practised 

 from it, commences on the flank and belly by numerous superficial divisions, 

 which unite in two principal radicles and afterwards become a single trunk, 

 placed in the substance, or on the external surface of the panniculus carnosus, 



