70 ANTHROPOLOGY. 



round, and covered by a great quantity of fat ; this forms the fold of the 

 nates. It arises from the posterior fifth of the crest of the ilium, from the 

 rough surface between the crest and the superior semicircular ridge of this 

 bone, from the posterior surface of the sacrum, and from the sides of the 

 coccyic. The flat and tliick tendon of this muscle is inserted into a rough 

 ridge, which leads from the trochanter to the linea aspera ; also into the 

 upper third of that line, and into the fascia lata. Use : to extend the thigh, 

 to abduct and rotate it outwards, and to support and extend the pelvis and 

 the trunk on the lower extremity. 



Glntoiiis medius^ triangular, and thinner than the last, arises from the 

 three anterior fourths of the outer edge of the crest of the ilium, and from 

 the surface of the ilium, and is inserted into the upper and outer part of the 

 great trochanter, being also attached anteriorly to the tendon of the glutseus 

 maximus. Use : to abduct and rotate the thigh, and to maintain the pelvis 

 in equilibrium on the femur. 



Glutceus 'Minimus arises from the inferior semicircular ridge on the 

 dorsum of the iUum, and from the rough surface between it and the edge 

 of the acetabulum. The fibres converge and end in a strong, round, 

 twisted tendon, which is inserted into the upper and anterior part of the 

 great trochanter. Use : similar to the last. It also strengthens the ilio- 

 femoral articulation. 



Pyriformis is a flattened triangular muscle, the base at the sacrum 

 within the pelvis, the apex at the trochanter. It arises within the pelvis, 

 and is inserted into the upper part of the digital fossa at the root of 

 the great trochanter. Use : to abduct the thigh, to extend and rotate it 

 outwards. 



Gemelli, two smaller muscles, placed behind the ilio-femoral articulation, 

 between the ischium and trochanter. The superior arises from the spine 

 of the ischium, and is inserted into the upper part of the digital fossa of the 

 great trochanter. The inferior arises from the upper part of the tuber ischii, 

 and is also inserted into the digital fossa. Use : to rotate the thigh outwards 

 and to abduct it. 



Obturator internus is situated partly within the pelvis and partly behind 

 the ilio-femoral articulation. It arises within the pelvis from the superior 

 surface of the thyroid ligament and from the circumference of the thyroid 

 foramen, and is inserted into the digital fossa of the great trochanter. Use : 

 to abduct and rotate the thigh outwards; also to act on the capsular 

 ligament. 



Quadratus femoris arises from the external surface of the tuber ischii, 

 anterior to the tendon of the semi-membranosus. It is inserted into the 

 inferior and posterior part of the great trochanter, and into the posterior 

 inter-trochanteric line. Use: to abduct and rotate the thigh outwards. 



Obturator externus, situated at the upper, posterior, and internal portion 

 of the thigh, arises from the inferior surface of the thyroid or obturator 

 ligament, and from the surrounding surfaces of the pubes and ischiam. It 

 is inserted into the lower part of the digital fossa. Use : to adduct the 

 thigh and rotate it outwards. 

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