146 OF THE ANTERIOR CAVA. 



doing which it is joined, near to its upper extremity, by a 

 large trunk, called the ulnar. It is also united with a large 

 vein, towards its low^er extremity, termed the spiral ; and 

 these accessions increase the bulk of the humeral. Just at 

 the point where the vessel loses the name of humeral, a 

 large vein unites with the radial, to swell the bulk of the 

 lower end of the humeral ; and this additional vein is called 

 the superficial brachial. All those vessels pass by the title 

 of superficial brachial, wdiich may be seen v/ith the naked eye, 

 from above the knee to the point of the shoulder, swelling over 

 the bodies of the extensor muscles. Just behind the knee the 

 superficial brachial unites with the radial ; which last, exactly 

 posterior to the joint, forms a venous circle ; ultimately be- 

 coming the internal metacarpal, to divide above the fetlocks, 

 into the two plantars ; which are immediately concerned in 

 bringing the blood from the fore feet. 



These vessels originate from the capillaries, in which 

 arteries terminate ; and bring back the blood to, or end in, 

 the heart. 



The jugulars, one of the principal divisions of the anterior 

 cava, run down one on each side of the trachea. The main 

 trunk arises from the foramen lacerum basis cranii ; w^hence 

 it soon after appears at the back of the jaw. In this situation 

 it receives several branches ; the most remarkable of which 

 are three vessels from the ear {Fig 17) ; a large trunk (the 

 temporal) {Fig 17 . e), originating in front of the masseter 

 muscle ; where it springs from a junction with the facial 

 {Fig ]7 . d) ; wdiich chiefly follows the course of the artery ; 

 receiving the blood of the labial {Fig 17 . c). From the 

 junction of the facial and the temporal grows the submaxil- 

 lary {Fig 17 . b) ; which takes the course of the artery in 

 the first instance ; and ultimately joins the jugular, at what 

 is generally termed its division into two parts. The sub- 

 maxillary is that portion which proceeds toward the channel 

 of the lower jaw^ ; and between it and the temporal are 

 numerous communicating trunks. These are necessary, 

 lest the blood should either be stayed in its course, or the 

 vessels containing it be burst, through the strong contrac- 

 tions of the powerful masseter muscle, which is employed 

 during mastication. As a further protection against such 

 an accident, within the substance of the masseter muscle, a 



