626 



THE ARTERIES. 



The Sciatic Artery (Fig. 375), the larger of the two terminal branches of the 

 anterior trunk of the internal iliac, is distributed to the muscles at the back of the 

 pelvis. It passes down to the lower part of the great sacro-sciatic foramen behind 

 the internal pudic artery, resting on the sacral plexus of nerves and Pyriformis 

 muscle, and escapes from the pelvis through this foramen between the Pyriformis 

 and Coccygeus. It then descends in the interval between the trochanter major and 



tuberosity of the ischium, ac- 

 companied by the sciatic nerves, 

 and covered by the Glutens 

 maximus, and is continued down 

 the back of the thigh supplying 

 the skin, and anastomosing with 

 branches of the perforating arte- 

 ries. 



Within the pelvis it distrib- 

 utes branches to the Pyriformis, 

 Coccygeus, and Levator ani 

 muscles ; some haemorrhoidal 

 branches, which supply the 

 rectum, and occasionally take 

 the place of the middle hsemor- 

 rhoidal artery; and vesical 

 branches to the base and neck 

 of the bladder, vesiculae semi- 

 nales, and prostate gland. Ex- 

 ternal to the pelvis it gives off 

 the following branches : 



Coccygeal. 



Inferior Gluteal. 



Comes Nervi Ischiadici. 



Muscular. 



Articular. 



The coccygeal branch runs 

 inward, pierces the great sacro- 

 sciatic ligament, and supplies 

 the Gluteus maximus, the in- 

 tegument, and other structures 



O ' 



on the back of the coccyx. 



The inferior gluteal branches, 

 three or four in number, supply 

 the Gluteus maximus muscle, 

 anastomosing with the gluteal 

 artery in the substance of the 

 muscle. 



The comes nervi ischiadici 

 is a long, slender vessel which 

 accompanies the great sciatic 

 nerve for a short distance ; it 

 then penetrates it and runs in 

 its substance to the lower part 

 of the thigh. 



The muscular branches supply the muscles on the back part of the hip, anas- 

 tomosing with the gluteal, external branch of the obturator, internal and exter- 

 nal circumflex, and superior perforating arteries. 



Some articular branches are distributed to the capsule of the hip-joint. 



The Ilio-lumbar Artery, given off from the posterior trunk of the internal 



Termination 

 of internal 

 circumflex. 



JSuperior 

 perforating. 



Middle 

 perforating. 



Inferior 

 perforating. 



Termination of 

 proftinda. 



Superior muscular. 



Superior external 



articular. 



Inferior muscular. 



Fio. 375. The arteries of the gluteal and posterior femoral 

 regions. 



Superior internal 

 articular. 



