332 THE ANATOMY OF THE HORSE. 



mare it is represented bj' the ovarian artery, which passes in a tortuous 

 manner between the layers of the uterine broad ligament to reach the 

 ovary. It gives off a uterine branch to the uterine horn. 



8. The Posterior Mesenteric Artery. This vessel is usually detached 

 at the 4th lumbar vertebra, a little behind the origin of the spermatics, 

 but this relationship may be reversed. 



The External Iliac Artery is, speaking generally, the vessel of 

 supply to the hind limb. It is regarded as a terminal branch of the 

 aorta, and it has its root at the body of the 5th lumbar vertebra. It 

 descends with a curved course at the pelvic inlet, and at the anterior 

 border of the pubis it is directly continued as the femoral artery. It is 

 placed immediately beneath the peritoneum, and each is related on its 

 outer side to the psoas parvus, sartorius, and iliacus muscles, the tendon 

 of the first of these separating it from the great crural nerve. On the 

 inner side it is related successively to the common iliac and external 

 iliac veins, the former separating it from the internal iliac artery. Its 

 branches are ; — 



1. The CiRcuiiPLBX Iliac Artery. This is a large artery detached 

 from the outer side of the external iliac close to its origin. It passes 

 outwards across the psoas muscles ; and at the outer edge of the psoas 

 magnus it divides into an anterior and a posterior branch. The former 

 is distributed in the flank, beneath the internal oblique muscle ; and 

 the latter perforates the oblique muscles near the bony angle of the 

 haunch, and descends to the thigh. 



2. The Artery of the Cord (Plate 44). This is a slender vessel 

 arising close to the preceding, or it may come from the aorta itself 

 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 origin, 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 abdomi- 

 nal 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. 



