522 



THE MUSCLES AND FASCIA 



The Gemelli (Fig. 377) are two small muscular fasciculi, accessories to the 

 tendon of the Obturator internus, which is received into a groove between them. 

 They are called superior and inferior. 



The Gemellus superior (in. gemellus superior), the smaller of the two, arises 

 from the outer surface of the spine of the ischium, and, passing horizontally 

 outward, becomes blended with the upper part of the tendon of the Obturator 

 internus, and is inserted with it into the inner surface of the great trochanter. 

 This muscle is sometimes wanting. 



Relations. By its superficial surface, with the Glutens maximus and the sciatic vessels and 

 nerves; by its deep surface, with the capsule of the hip-joint; by its upper border, with the lower 

 margin of the Pyriformis; by its lower border, with the tendon of the Obturator internus. 



Obturatot 

 artery. 



Anterior division of 

 obturator nerve. 



Anterior inferior 

 iliac spine. 



'apxiifar liga- 

 -''nieiit purtly 

 cut 



Posterior division 

 of obturator 

 nerve. 



Internal circum- 

 flex artery. 



FIG. 389. Obturator extern us muscle. (From a preparation in the Museum of the Royal College of 



Surgeons of England.) 



The Gemellus inferior (m. gemellus inferior) arises from the upper part of the 

 tuberosity of the ischium, where it forms the lower edge of the groove for the 

 Obturator internus tendon, and, passing horizontally outward, is blended with 

 the lower part of the tendon of the Obturator internus, and is inserted with it 

 into the inner surface of the great trochanter. 



Relations. By its superficial surface, with the Gluteus maximus and the sciatic vessels and 

 nerves; by its deep surface, with the capsular ligament of the hip-joint; by its upper border, 

 with the tendon of the Obturator internus; by its lower border, with the tendon of the Obturator 

 externus and Quadratus femoris. 



The Quadratus femoris (m. quadratus femoris] (Fig. 387) is a short, flat 

 muscle, quadrilateral in shape, situated between the Gemellus inferior and the 

 upper margin of the Adductor magnus. It arises from the upper part of the exter- 

 nal lip of the tuberosity of the ischium, and, proceeding horizontally outward, is 



