CHAP, vii.] THE CAT'S ORGANS OF CIRCULATION. 213 



of the abdominal cavity, the aorta gives off two large arteries which go 

 one to each hind limb respectively, and each of which is named an 

 external iliac artery. After continuing on for a short space further, 

 the aorta gives off another pair of rather smaller vessels called the 

 internal iliac arteries (Fig. 105, i) ; the aorta then immediately bends 

 sharply upwards, and thenceforth continues onwards, gradually 

 narrowing, beneath the middle of the tail as the caudal artery -, which 

 gives off twigs to the caudal muscles. 



The INTERNAL ILIAC, or hypogostric artery, dips down into the 

 pelvis, and gives off a variety of branches. Amongst them we have 

 the superior resical, which goes to the side of the bladder, and is con- 

 nected with the umbilicus (or navel) by a fibrous cord a relic of 

 an important foetal structure ; the inferior vesical, which goes to the 

 bladder, and, in the male, to a part to be hereafter described as the 

 prostate gland ; the uterine and pudic arteries, which go to the uterus 

 and external generative organs ; the gluteal artery, which passes out 

 of the pelvis, between the pyriforinis and gluteal muscles, supplying 

 the latter ; and the sciatic artery, which passes out of the pelvis at the 

 great sciatic notch, and goes (between the greater trochanter and the 

 tuberosity of the ischium) to the muscles of the hip and thigh. 



21. The EXTERNAL ILIAC artery is very conspicuous on the 

 inside of the thigh. It passes backwards, downwards, and outwards, 

 and soon gives off a large branch called the obturator artery, which 

 passes out of the pelvis through the obturator foramen. From the 

 obturator artery is given off the epigastric artery, which passes for- 

 wards in the middle of the abdominal wall, and anastomoses with 

 branches of the internal mammary artery. 



Having passed beneath Poupart's ligament to the thigh, the ex- 

 ternal iliac assumes the name of the femoral artery, and descends 

 along the inside of the thigh, resting successively on the psoas, 

 pectineus, and adductor muscles. Near its origin, the femoral gives 

 off a large branch called the deep femoral, which passes in through 

 the adductor muscle, and ramifies in the muscles of the hinder and 

 outer parts of the thigh. 



_ Before reaching the back of the knee-joint, the femoral artery 

 divides into the anterior and posterior tibial arteries. 



The POSTERIOR TIBIAL ARTERY runs down behind the tibia, upon 

 the tibialis posticus and flexor longus digitorum muscles, to the inner 

 side of the os calcis, where it divides into the external and internal 

 plantar arteries. The first of these goes to the base of the fifth 

 metatarsal, and then passes obliquely between the metatarsals to 

 anastomose with the dorsal artery of the foot, so forming a plantar 

 arch. The second, or internal plantar, proceeds along the inner side 

 of the sole of the foot towards the index. 



The posterior tibial gives origin to a branch called the peroneal 

 artery, which descends behind the leg close to the fibula, and in 

 contiguity with the flexor longus hallucis to the outside and back of 

 the os calcis. 



The anterior tibial artery passes forwards to the front of the 



