THE THIGH. 



FIG. 79. The anterior femoral region. 



FIG. 80. The exposure of the femoral artery before its entrance into Hunter's canal. 



FIG. 8 1. The subperitoneal exposure of the external iliac artery. Below Poupart's ligament the femoral vessels 

 have also been exposed. 



internus takes origin from the inner surface of the obturator membrane and from the surrounding 

 bones; it leaves the pelvis through the lesser sacrosciatic foramen and passes to the trochanteric 

 fossa, accompanied by the superior and inferior gemelli muscles (arising from the spine and 

 from the tuberosity of the ischium respectively). The obturator externus runs from the outer 

 surface of the obturator membrane to the trochanteric fossa. The quadratus jemoris passes 

 from the tuberosity of the ischium to the crista intertrochanterica (linea quadrati). 



After dividing the gluteus maximus at right angles to the course of its muscular fibers (Fig. 

 78) the inferior gluteal nerve is exposed as it leaves the pelvis through the infrapyriform fora- 

 men and radiates upward into the substance of the divided muscle. The other nerves leaving 

 the pelvis by way of the infrapyriform foramen to reach the skin of the posterior surface of the 

 thigh are the small sciatic, the great sciatic (the portion which subsequently becomes the pero- 

 neal nerve frequently perforating the pyriformis muscle), and the internal pudic. The latter 

 nerve immediately re-enters the pelvis, however, through the lesser sacrosciatic foramen. The 

 branches of the internal iliac artery escaping from the pelvis below the pyriformis muscle are 

 the sciatic, chiefly supplying the gluteus maximus and giving off the comes nervi ischiadici, and 

 the internal pudic, which is accompanied by the pudic nerve and supplies the terminal portion 

 of the rectum, the perineum, and the external genitalia. The suprapyriform foramen is ex- 

 posed by dividing the gluteus medius muscle (Fig. 78). The gluteal artery leaves the pelvis 

 through this foramen; it sends a branch between the gluteus maximus and medius and gives 

 off another below the gluteus medius. This artery is accompanied by the superior gluteal nerve, 

 which passes over the superior margin of the pyriformis and supplies the gluteus medius, the 

 gluteus minimus, and the tensor fasciae latae muscles. It should be noted that one artery and 

 one nerve leave the pelvis above the pyriformis muscle, and that two arteries and four nerves 

 pass out below this structure. 



THE THIGH. 



The Muscles. The muscles of the thigh surround the femur in such a manner that only 

 the great trochanter above, the condyles below, are palpable beneath the skin. We differentiate 

 the anterior group of extensors, the posterior group of flexors, and the internal group of adduc- 

 tors (Figs. 79 and 82). There is also a superficial group composed of the tensor JOSCUB lata, 

 passing from the anterior superior spine of the ilium to the fascia lata, and of the sartor ius, which 

 arises from the anterior superior iliac spine and inserts into the tibia below the internal tuber- 

 osity and as far forward as the tibial tubercle. 



The quadriceps extensor cruris consists of four parts: the rectus, the vastus externus, the 

 vastus internus, and the crureus. The rectus muscle arises by two short tendons from the an- 

 terior inferior iliac spine and from the bone alongside of the acetabulum; the vastus externus 

 springs from the great trochanter, from the outer lip of the linea aspera, and from the external 

 intermuscular septum; the vastus internus takes origin from the inner lip of the linea aspera 



