382 SURGICAL APPLIED ANATOMY. [Chap. xix. 



the buttock and loss of the gluteal fold. These 

 symptoms depend upon the flexion of the hip, which is 

 practically constant in every case of the malady before 

 treatment. It is incorrect to say, as some books 

 still assert, that these changes are due to wasting of 

 the gluteal muscles, since they appear at too early 

 a period for any considerable muscular atrophy to 

 have taken place. It is true that these symptoms 

 are much exaggerated by the wasting of the muscle 

 that occurs later on in the course of the hip affection. 



With regard to the vessels and nerves of the but- 

 tock, if a line be drawn from the posterior superior 

 spine to the top of the great trochaiiter when the thigh 

 is rotated in, a point at the junction of the inner with 

 the middle third of that line will correspond to the 

 gluteal artery as it emerges from the sciatic notch. 

 A line drawn from the posterior superior spine to the 

 outer part of the tuber ischii crosses both the posterior 

 inferior and ischial spines. The former is about 

 two inches and the latter about four inches below 

 the posterior superior process. The sciatic artery 

 reaches the gluteal region at a spot corresponding to 

 the junction of the middle with the lower third of this 

 line. The position of the pudic artery as regards the 

 buttock is not difficult to indicate, since it crosses over 

 the ischial spine in passing from the great to the small 

 sacro-sciatic foramen. 



A line drawn from the point just given for 

 the sciatic artery down the back of the limb, so as to 

 lie about midway between the great trochanter and the 

 ischial tuberosity, will correspond to the course of the 

 great sciatic nerve. 



The skin over the buttock is thick and coarse, 

 and is frequently the seat of boils. From the appear- 

 ance it presents in very fully injected specimens, it 

 would appear that its blood supply is not quite so free 

 as it is in many other parts of the surface. 



