450 MUSCLES. 



Between the tendon of this muscle and the gemini is a long 

 bursa; a second is found where the muscle plays over the is- 

 chium. 



It rotates the limb outwards. 



The Quadratus Femoris, 



Is lower down than the other muscles. It arises, tendinous 

 and fleshy, on the outer side of the ischium, from the ridge 

 which constitutes the exterior boundary of the tuberosity. Its 

 fibres are transverse, and are inserted, fleshy, into the rough 

 ridge of the os femoris, on its back part, which goes from one 

 trochanter to the other. 



It rotates the limb outwards. A bursa exists between it and 

 the trochanter minor.* 



The Obturator Externus, 



Is concealed, in front, by the pectineus and triceps adductor, 

 and, behind, by the quadratus femoris: to get a satisfactory 

 view of it, therefore, these muscles should be detached from the 

 bone. It arises from the whole anterior circumference of the 

 foramen thyroideum, excepting the place where the obturator 

 vessels come out, and from the anterior face of the ligamentous 

 membrane stretched across it. 



The fibres of this muscle converge, pass beneath the capsu- 

 lar ligament of the hip joint adhering to it, and terminate suc- 

 cessively in a round tendon, which is inserted into the inferior 

 part of the cavity on the posterior surface of the os femoris, at 

 the root of the trochanter major. The course of the tendon of 

 this muscle is marked on the neck of the thigh bone by a su- 

 perficial fossa. 



It rotates the thigh outwards. 



* Varieties. Occasionally, this muscle is absent; more rarely it is divided into 

 a great number of fasciculi, amounting in one instance to thirty. 



