SCIATIC AND GLUTEAL ARTERIES. 429 



V. SCIATIC ARTERY. 



The sciatic artery, the largest branch of the internal iliac trunk, excepting 

 the gluteal, is distributed to the muscles on the back of the pelvis. It 

 descends upon the pelvic surface of the pyriformis muscle and the sacral 

 plexus of nerves; and, turning backwards beneath the border of that muscle, 

 it passes between it and the superior gemellns, and thus escapes from the 

 pelvis, along with the great sciatic nerve and the pudic artery, at the lower 

 part of the great sciatic foramen. Outside the pelvis, this artery lies in the 

 interval between the tuber ischii and the great trochanter, covered by the 

 gluteus maximus. 



BRANCHES. The sciatic artery gives off several branches to the external rotator 

 muscles of the thigh, on which it lies, and to the great gluteus by which it is con- 

 cealed. Two others have received special names, viz., the following. 



(a) The coccygeal, inclines inwards, and piercing the great sacro-sciatic ligament, 

 reaches the posterior surface of the coccyx, and ramifies in the fat and skin about 

 that bone. 



(b) The other named branch, comes nervi iscliiadici, runs downwards, accompanying 

 the sciatic nerve, along which it sends a slender vessel. 



Some of the branches of this artery are distributed to the capsule of the hip-joint ; 

 whilst others, after supplying the contiguous muscles, anastomose with the gluteal, 

 the internal circumflex, and the superior perforating arteries, in the upper part of the 

 long flexor muscles of the thigh.. 



VI. GLETTEAL ARTERY. 



The gluteal artery, the largest branch of the internal iliac, is distributed 

 to the muscles on the outside of the pelvis. It inclines downwards to the 

 great sacro-sciatic foramen, and, escaping from the cavity of the pelvis, 

 between the contiguous borders of the middle gluteal and the pyriform 

 muscles, divides immediately into a superficial and a deep branch. 



BRANCHES. (a) The superficial branch, running between the gluteus maximus and 

 gluteus medius, divides into ramifications which are most copiously distributed to the 

 gluteus maximus, and anastomose with the sciatic and posterior sacral arteries. 



(b) The deep branch, situated between the gluteus medius and gluteus minimus, 

 runs in an arched direction forwards, and divides into two other branches. One of 

 these, the superior branch, follows the upper border of the gluteus minimus beneath 

 the middle gluteal muscle and the tensor of the fascia lata, towards the anterior iliac 

 spine, and, after having freely supplied the muscles between which it passes, anasto- 

 moses with the circumflex iliac and the ascending branches of the external circum- 

 flex arteries. The second or inferior branch descends towards the great trochanter, 

 supplies the gluteal muscles, and anastomoses with the external circumflex and the 

 sciatic arteries. 



(c) A nutrient, branch enters the hip bone at the place where the artery emerges 

 from the pelvis. 



VII. 1LIO-LUMBAR ARTERY. 



The ilio-lumbar artery resembles in a great measure one of the lumbar 

 arteries. It passes outwards beneath the psoas muscle and the external 

 iliac vessels, to reach the margin of the iliac fossa, where it separates into a 

 lumbar and an iliac division. The first of these ramifies in the psoas and 

 quadratus muscles, communicating with the last lumbar artery, and fur- 

 nishing branches to the vertebral canal. The second or iliac division, 

 turning downwards and outwards, either in the iliacus muscle or between 

 it and the bone, anastomoses with the circumflex iliac artery, and even with 

 the external branches of the epigastric. 



