THE SCIATIC AND GLUTEAL ARTERIES. 



481 



(#) The coccygeal branch, inclining inwards, pierces the great sacro-sciatic liga- 

 ment, and is distributed mainly to the glutens maximus, two or three offsets 

 perforating that muscle and ramifying in the subcutaneous tissue over the sacrum 

 and coccyx. 



(c) The anastomotic branch, directed outwards to the hollow on the inner side 

 of the great trochanter, supplies the external rotator muscles and the hip-joint, and 

 anastomoses with offsets of the gluteal artery, with the ascending branch of the 

 internal circumflex artery, and with the first perforating artery. 



(d) The comes nervi ischiadici (vi) enters the great sciatic nerrft,-which it 

 supplies, and anastomoses with twigs of the perforating arteries. 



(e) Several cutaneous branches pass to the integument at the lower border 

 of the gluteus maximus, along with branches of the small sciatic nerve. 



Fig. 384. ARTERIES OF THE BACK OF THE 

 PELVIS. (Tiedemann. ) 



a, iliac crest ; 6, ischial tuberosity ; c, great 

 trochanter ; d, integument round the anus ; e, great 

 sciatic nerve ; 1, trunk of the gluteal artery as it 

 issues from the great sacro-sciatic foramen, the super- 

 ficial part is cut short, the deep part is seen passing 

 forwards on the surface of the gluteus minimus 

 muscle ; 2, on the great sacro-sciatic ligament, points 

 to the pudic artery as it winds over the ischial 

 spine ; 2', the continuation of the artery in the peri- 

 neum ; 3, 3, sciatic artery ; the upper figure points 

 to the trunk of the vessel, from which the anasto- 

 motic branch is seen running outwards towards the 

 great trochanter ; the lower figure indicates the con- 

 tinuation of the artery along the back of the thigh ; 

 4, first perforating artery. 



Varieties. The sciatic artery occasionally 

 arises in common with the gluteal,, leaving 

 that vessel outside the pelvis, at the upper 

 border of the pyriformis muscle. In a few cases 

 this artery has been found much enlarged, 

 and forming- the main artery of the limb (see 

 varieties of the femoral artery). The comes 

 nrrri ischiadici has been seen by Hyrtl of large 

 size, and continued along the thigh to join the 

 popliteal artery, a little above the knee-joint. 



8. The gluteal artery (iii), the 

 largest branch of the internal iliac, is 



distributed to the muscles on the outer side of the pelvis. It passes backwards 

 between the lumbo-sacral cord and the first sacral nerve, turns round the upper 

 margin of the great sacro-sciatic foramen, and divides opposite the interval between 

 the gluteus medius and pyriformis muscles into a superficial and a deep part. 

 Before leaving the pelvis the gluteal artery gives some twigs to the pyriformis and 

 obturator interims muscles, and one or two branches to the hip-bone. 



(a) The superficial part, the smaller of the two divisions, passes backwards 

 between the contiguous borders of the gluteus medius and pyriformis muscles, and 

 divides into a number of branches, which are distributed to the gluteus maximus, 

 and anastomose with the sciatic and the posterior branches of the lateral sacral 

 arteries. 



(&) The deep^ part divides again into two branches, which run forwards between 

 the gluteus medius and minimus muscles. The superi&r branch courses along the 

 upper border of the gluteus minimus towards the anterior superior iliac spine, and, 

 after supplying the muscles between which it is placed, anastomoses with the 



