194 THE SURGICAL ANATOMY OF THE HORSE 



which separates it from the internal iliac artery. Arriving at the brim 

 of the pelvis, we find the artery between the pectineus and sartorius 

 muscles, and it now becomes directly continued as the femoral artery. 

 The collateral branches of the external iliac artery are : 



1. The Artery of the Cord. — This vessel is sometimes called the small 

 testicular artery, and occasionally also the cremasteric artery. It is a 

 long and very slender vessel which is usually given off by the external 

 iliac artery near the origin of the latter from the posterior aorta. In 

 some cases it is a branch of the aorta itself 



Its course is downwards, backwards, and outwards across the ureter, 

 when it runs parallel to the spermatic artery, which arises from the pos- 

 terior aorta and behind which it is placed. It thus passes to the internal 

 abdominal ring, where it becomes a constituent part of the spermatic 

 cord. Before reaching the cord it gives off branches to the peritoneum, 

 the iliac glands, the ureter and the vas deferens. It is distributed to 

 the spermatic cord. In the mare it is represented by the uterine artery 

 which is a larger vessel, and which passes between the two layers of 

 the broad ligament. It divides into two branches, one of which — the 

 ovarian — is distributed to the ovary, whilst the other passes to the horn 

 of the uterus and anastomoses with the uterine artery. 



2. The CircumJiex-I/iac Artery. — This branch is given off from the 

 parent vessel immediately after the latter leaves the posterior aorta. 

 Occasionally it leaves the aorta itself, and takes a course outwards between 

 the peritoneum and the aponeurosis covering the sublumbar muscles. 

 It passes beneath the psoas magnus muscle and over the spermatic artery 

 and ureter, and near the outer border of the psoas magnus it splits 

 into anterior and posterior divisions. The anterior division descends in 

 the flank and is distributed in the transverse and internal oblique 

 muscles of the abdomen, its terminal ramifications anastomosing with 

 those of the lumbar and last few intercostal arteries. 



The posterior division also distributes filaments to the oblique and 

 transverse muscles, and passes between the internal oblique and iliacus 



