Il6 ANATOMY OF THE DOMESTIC FOWL 



Obturator Extemus (Fig. 24, No. 9) . Location. — External postero- 

 lateral side of the pelvis. 



Origin.- — ^From the posterior half of the periphery of the ischiatic 

 foramen and the concavity found on the external surface of the 

 lateral part of the pelvis. 



Insertion. — The fibers pass across to the femur and are inserted 

 by a broad, flat tendon to the shaft of the femur just below the 

 trochanter. 



Shape — Thick, fleshy. 



Relations. — Lies just above the femoro-caudal muscle, the sciatic 

 nerve and femoral artery pass over and external to its tendon. 



Action. — Pulls the head of the femur backward. 



Obturator Intemus (Fig. 16, No. E, i). Location. — Occupies the 

 space between the ischium and the pubis. 



Origin. — From the ventral surface of the ischium, including the 

 posterior border, from the inner line of the corresponding post- 

 pubis, and from the membrane covering the space between these 

 two bones. 



Insertion. — ^Becoming dense, subcylindrical, and strong, it passes 

 through the obturator foramen and is inserted to the outer part of 

 the trochanter of the femur, in common with the gemellus and 

 opposite to the insertion of the gluteus medius. 



Shape.- — Subtriangular and flat with a central tendon; bipenni- 

 form. 



Relations. — Outside the pelvis the tendon lies upon the gemellus 

 and is external to it. Fills the obturator foramen and the space 

 between the ischium and the pubis. 



Action. — Acts as a posterior stay to the head of the femur. 



Gemellus (Fig. 25, No. 5) . Location. — Posterior to the head of 

 the femur. 



Origin. — From the fossa between the acetabulum and the obtura- 

 tor foramen, and on the outer side of the pelvis. 



Insertion. — Its fibers are attached by fascia to the tendon of the 

 obturator iatemus, and pass directly to the trochanter of the femur 

 where they insert in common with that of the obturator internus. 



Shape. — Strong, thick, chunky. 



Relations. — Postero-external to the head of the femur. 



Action. — Like the two preceding, when the head of the femur is 

 fixed, it pulls the pelvis forward and steadies it on the head of the 

 femur. 



