460 The Thigh 



line with its convexity towards the great trochanter, which marks the 

 great sacro-sciatic notch, and ends on the ischial spine. From the 

 ischial tuberosity arise the hamstring muscles, biceps, and semi- 

 tendinosus and semi-membranosus. 



The sciatic nerves (p. 379) leave the pelvis below the pyriformis ; 

 the greater then descends between the trochanter and the tuberosity, 

 emerging in the mid-space from beneath the border of the glutens 

 maximus. It lies in this hollow so that it may be out of the way of 

 pressure in the usual sitting posture. If, however, one sits sideways 

 or on the edge of the chair, the nerve is compressed and numbness 

 and discomfort result. For nerve-stretching^ see p. 380 ; for the course 

 of the gluteal artery, see p. 374. 



The gluteus maximus arises from the back of the ilium, sacrum, 

 coccyx, and sacro-sciatic ligament, and passes downwards and out- 

 wards ; its thick and free lower border passes over the ischial 

 tuberosity, and is inserted below the great trochanter. The upper 

 two-thirds of the muscle glide as a strong, thin tendon over the 

 trochanter, and are inserted with the tensor fasciae femoris into the 

 ilio-tibial band. The muscle is separated from the tuberosity and 

 the trochanter by two bursae, and in men who sit a great deal, such 

 as coachmen, tailors, and weavers, the ischial burs a is apt to be greatly 

 irritated, and even to suppurate. The inflamed bursa has a very 

 unpoetic name. When the trochanteric bursa is inflamed the signs 

 may at first suggest hip-joint disease ; but there is no swelling of the 

 joint itself, and the femur may be rotated in the acetabiflum without 

 causing distress. 



T\xt fold of the nates runs obliquely downwards and outwards in 

 the direction of the lower border of the gluteus maximus, with which, 

 however, it has no anatomical association. It is the result of the 

 creasing of the skin when the thigh is extended. When it is flexed 

 the crease and the fold disappear, which they would not do if their 

 presence had depended upon the existence of the border of the 

 muscle. 



The pyriformi s may be depicted as passing downwards and out- 

 wards from the notch already marked out, to the top of the great 

 trochanter. It forms an elongated, triangular figure. Through the 

 notch, above the muscle, emerge the gluteal artery and the superior 

 gluteal nerve. As has already been shown (p. 374), the point of 

 emergence of the artery is at the junction of the upper and middle 

 thirds of a line running from the posterior superior spine to the top of 

 the great trochanter. 



THE FEMUR 



The femur generally changes its form with age ; in childhood 

 the neck is short and in an almost vertical line with the shaft. In adult 

 life it stands off at an obtuse angle, and often in old age, but by no 



