777 K ULUTKM, 



22:; 



small trochanter; it may be absent or replaced by the gemellus 

 inferior. 



M. Obturator Externus. Origin, inner half of the superficial 

 surface of the obturator membrane, body of the pubis, rarni 

 of the pubis and ischium; passes out in a groove between the 

 acetabulum and tuber ischii, then up and backward, close 

 to the lower and posterior surface of the neck of the femur to 

 the bottom of the digital fossa. Sometimes bursa is between 

 it and capsule. 



Nerves. Iliopsoas by the second and third lumbar; those 

 for the iliacus are given off by the anterior crural; glutens 

 maximus by the inferior gluteal nerve; gluteus medius and 

 minimus by the superior gluteal nerve; obturator internus 

 gemelli, pyriformis, and quadratus femoris by the sacral plexus; 

 obturator externus by the obturator nerve. 



Actions of the glutei on the lower limb: 



Flexion. 



Glut, med., anterior fibers. 

 Glut, min., anterior fibers. 



Adduction. 



Glut, med., anterior fibers (in 



sitting posture). 

 Glut, min., anterior fibers 



(in sitting posture). 



Rotate in. 



Glut, med., anterior fibers. 

 Glut, min., anterior fibers. 



Extension. 



Glut, maximus. 



Glut, med., posterior fibers. 



Glut, min., posterior fibers. 



Abduction. 

 Glut., max., slight, 

 strong, 



Glut, med., 

 Glut, min., 



whole 

 muscle, espe- 

 cially mid- 

 portion. 



Rotate out. 



Glut. max. 



Glut, med., posterior fibers. 



Glut, min., posterior fibers. 



The glutens nui.rimus extends the trunk on the thigh as in 

 ascending stairs; in walking it is not used, as the erect position 

 is maintained by ligaments; steadies and supports the knee 

 by the iliotibial band. 



The iliopsoas flexes the thigh and rotates out; flexes the 



