The Gluteal Region. , 311 



gluteal nerve; the pyriformis muscle; the internal pudic 

 artery, pudic nerve and sciatic artery ; small and great scia- 

 tic nerves ; the inferior gluteal nerve emerging from the 

 pelvis ; the obturator internus muscle, with the gemellus 

 superior above and the gemellus inferior below; a small 

 portion of the obturator externus ; the quadratus femoris ; 

 the upper portion of the adductor magnus, and the origins 

 of the semi-membranosus, semi-tendinosus and the biceps 

 muscles. Besides the above structures, the following also 

 are exposed : A portion of the ilium, the posterior superior 

 and the posterior inferior spines, the greater and lesser 

 sacro-sciatic ligaments, the spinous process and the tuber- 

 osity of the ischium; the bursa overlying the latter; the 

 great trochanter with its bursa; the posterior surface of 

 the sacrum and the side of the coccyx covered by liga- 

 ments. 



Landmarks for the Gluteal Region. The posterior 

 superior spine can be felt by running the finger backwards 

 along the crest of the ilium to its termination. This spine 

 corresponds to the middle of the sacro-iliac joint and to 

 the level of the second sacral spine. The posterior inferior 

 spine is about one inch below the posterior superior spine, 

 lies one-quarter of an inch external to the line from the 

 latter spine to the outer border of the ischial tuberosity, 

 and corresponds to the lower limit of the sacro-iliac joint. 

 The tuberosity of the ischium lies near the lower border o 

 the gluteus maximus, while the spine of the ischium is 

 situated beneath a line drawn from the posterior superior 

 iliac spine to the outer border of the isehial tuberosity and 

 at a point, about two inches above the latter. This spine 

 lies about one and a quarter inches below the top of the 

 great trochanter. The third sacral spine may be found 

 after the second spine has been identified, as above de- 

 scribed, viz./ by its relationship to the posterior superior 



