GLUTVEAL REGION. 



501 



passed into the substance of the great glutaeus 

 muscle; these are from the glutaeal and ischiatic 

 arteries, and appear principally at the upper 

 and posterior part of the glutaeus medius; 

 2d, the whole of the glutaeus medius, the pos- 

 terior two-thirds of which had been covered by 

 the larger muscle ; 3d, at the posterior edge of 

 the glutaeus medius is the pyriformis muscle part- 

 ly concealed by it, and coming out of the supe- 

 rior sacro-sciatic foramen ; 4th, next below the 

 pyriformis lie the two gemelli, with the tendon 

 of the obturator intemus between them, and 

 below these is the quadratus femoris, having 

 underneath it the strong tendon of the obturator 

 extemus; 5th, the great sciatic nerve is seen 

 emerging from the superior sacro-sciatic fora- 

 men near the sciatic artery. Sometimes it 

 conies out entirely below the pyriformis; some- 

 times it descends in two branches, one of which 

 perforates that muscle, and they then unite. 

 The trunk passes directly downwards, cross- 

 ing the rotator muscles of the hip, and pass- 

 ing between the projecting tuberosity of the 

 ischium and the trochanter major. In this 

 part of its course it is accompanied by the 

 sciatic artery, which is seen about half an inch 

 to the internal or sacral side of the nerve, and 

 sends one considerable branch to supply the 

 nerve, and runs tortuously imbedded in its 

 neurilema. The course which the nerve and 

 artery here take will be represented by a line 

 drawn from the posterior superior spinous pro- 

 cess of the ilium to a spot midway between 

 the tuber ischii and trochanter major. Lastly, 

 in this view are exposed the bursal sacs, of 

 which there are several between the glutaeus 

 maximus and the subjacent pails. The most 

 considerable is found between it and the external 

 surface of the trochanter major. A consider- 

 able but smaller one is placed between its broad 

 tendinous expansion and the upper part of the 

 vastus externus, and two smaller ones com- 

 monly between the muscle and the os femoris 

 at the upper and back part of the thigh. The 

 ischiatic artery at the commencement of its 

 course is smaller than the glutaeal, and comes 

 down over the pyriformis muscle, and makes 

 its exit from the pelvis through the lower part 

 of the sciatic notch, between the pyriform and 

 levator ani muscles, above the lesser sciatic 

 ligament, and in front of the sciatic nerve ; it 

 sometimes passes between the roots of this 

 nerve. On the dorsum of the pelvis the sciatic 

 artery is covered by the glutaeus maximus 

 muscle, and may be seen by a similar dissec- 

 tion to that which exposes the glutaeal artery, 

 excepting that it is found about an inch and a 

 half lower down than the last-named vessel. 



The glutaeal artery comes out of the pelvis 

 at the upper part of the sciatic notch in com- 

 pany with the superior glutaeal nerve and vein. 

 It immediately winds upwards upon the dorsum 

 ilii, keeping close to the bone, and shortly 

 after its arrival upon the dorsum it divides into 

 branches principally distributed to the glutaeal 

 muscles. To expose this artery and its branches 

 in dissection, it is necessary to proceed as in 

 the dissection of the glutaeus maximus muscle. 



Next divide this muscle in a line from the 

 posterior superior spine of the ilium to the 

 tuberosity of the ischium. In making this dis- 

 section several large arteries and veins must be 

 injured. If the edges of the muscle be now 

 separated and the subjacent cellular membrane 

 removed, the glutaeal artery, accompanied by 

 one or two large veins and by the glutaeal nerve, 

 may be seen escaping from the sciatic notch 

 above the pyriform muscle, between it and the 

 glutaeus medius. This artery, as it escapes from 

 the pelvis, lies three inches and a half from the 

 mesian line, or from the spinous processes of 

 the sacrum. 



The glutaeal and ischiadic arteries, as we have 

 seen, are covered by the glutaeus maximus mus- 

 cle, and lie at such a depth from the surface 

 that they are not very liable to injury. Wounds, 

 however, of this part do occasionally implicate 

 these vessels, either in their large branches or 

 even the trunks themselves, and they have been 

 affected with aneurism, an instance of which 

 is mentioned by Mr. J. Bell,* and which 

 attained a considerable size. In the case of a 

 wound, its direction will lead us to the 

 situation of the artery ; and in the instance of 

 aneurism just mentioned, Mr. Bell ventured to 

 lay open the sac and thus reach the mouth of 

 the glutaeal artery, which he secured by liga- 

 ture, and this perhaps might be accomplished 

 in a very emaciated person; but generally 

 speaking the artery lies so deep, and the vessels 

 which must be wounded in making the neces- 

 sary incisions would by their bleeding so ob- 

 scure the operation, that the most experienced 

 surgeons do not recommend the attempt under 

 ordinary circumstances, but prefer the operation 

 of tying the internal iliac.f As a guide, how- 

 ever, to the situation of the glutaeal artery, 

 whether in the examination of a wound or in 

 operating upon it, its position on the dorsum 

 of the pelvis may be ascertained by drawing a 

 line from the posterior spinous process of the 

 ilium to the middle of the space between the 

 tuberosity of the ischium and trochanter major. 

 If this line is divided into three, the glutaeal 

 artery will be found emerging from the pelvis 

 at the juncture of its upper and middle thirds.} 



To return to the consideration of the anato- 

 mical structures which we expose in succession. 

 We are struck with the difference in texture of 

 the three glutaei muscles. The fibres of the 

 two smaller glutaei are of moderate size and 

 strength, while those of the larger glutaeus are 

 remarkable for their coarseness and large dimen- 

 sions. The relative situation of the three 

 muscles is also important. The position and 

 direction of the glutaeus maximus is just in 

 that line in which the greatest vigour of action 

 is required to erect the body by drawing the 

 back part of the pelvis towards the trochanter 

 major. In this operation it is assisted by the 

 position of the glutaeus medius and minimus, 



* Principles of Surgery, vol. i. p. 421. 



t See Med. Chir. Trans, vol. v. Also Guthrie on 

 Diseases of Arteries, p. 364. 



| See Harrison's Surgical Anatomy of the Art- 

 ries, vol. ii. p. 100. 



