DISSECTION OF THE ABDOMEN. 323 



Parallel and internal to the spermatic artery, it passes to the internal 

 abdominal ring, and is distributed to the spermatic cord. 



In the mare it is represented by the uterine artery. This, which is a 

 much larger vessel, passes between the layers of the broad ligament to 

 reach the uterus, being distributed to the body of that organ, and 

 anastomosing anteriorly with the uterine branch of the ovarian artery, 

 and posteriorly with the vaginal artery. 



3. The Prepubic Artery (Plates 45 and 46). This vessel arises at 

 the anterior border of the pubis, and marks the limit of the iliac and 

 femoral arteries. It forms, at its oi*igin, a short common trunk with the 

 deep femoral artery. It is about two or three inches in length, and it 

 passes on the anterior face of Poupart's ligament to the posterior edge of 

 the internal oblique, where, at the inner side of the internal abdominal 

 ring, it divides into the posterior abdominal and external pudic arteries. 



The Internal Iliac Artery. This vessel may be described as the 

 vessel for the supply of the pelvic walls and contents. It will be 

 described with the pelvis. 



The Posterior Vena Cava (Plates 43, 44, and 45). This great venous 

 trunk is formed to the right of the termination of the aorta, by the union 

 of the two common iliac veins. It passes forwards along the right side 

 of the lumbar vertebral bodies, until it reaches the upper border of the 

 liver. Here it descends in the anterior fissure of the liver, being 

 included between that organ and the diaphragm. Passing through the 

 foramen dextmm, it enters the thorax. It is related on its left side to 

 the aorta; and on its right to the psoas parvus, ureter, kidney, 

 suprarenal capsule, and lumbar sympathetic cord of the same side. It 

 receives the following branches : — 



1. L^imbar Veins, exactly corresponding to the arteries. 



2. Phrenic Veins, or sinuses (2). These begin in the muscular rim 

 of the diaphragm, and converge to the foramen dextrum, where they 

 join the vena cava. They are distinctly visible Avithout dissection in 

 the tendinous centre of the diaphrag-m (Plate 45). 



3. Spermatic Veins {Ovarian in the mare). The right and left veins 

 often unite before joining the vena cava. 



4. Renal Veins, the left longer than the right. 



5. Hepatic Veins. These join the vena cava while it lies in the 

 anterior fissure of the liver. They discharge the blood of the portal 

 system of veins, after it has circulated in the liver. 



Iliac Veins. There are external and internal iliac veins, with branches 

 coiresponding in all respects to the divisions of the homonymous arteries. 

 The external and internal iliac veins of each side, however, unite and 

 form a short trunk termed the common iliac vein, which is placed in the 

 angle of separation between the external and internal iliac arteries. The 

 right and left common iliac veins unite to form the posterior vena cava. 



