252 



THE ARTICTLATIOXS 



from it. First, the bearing surfaces of the femur and acetabulum preserve their 

 apposition to each other, so that the amount of articular surface of the head in the 

 acctaljulum does not sensibly diminish pari passu with the transit of the joint 

 from the extended to the flexed position, as would necessarily be the case if the 

 movement of the femoral head, like that of the thigh itself, was simply angular, 

 instead of rotatory and angular. ^Secondly, as rotation of the head can continue 

 until the ligaments are tight without being checked by contact of the neck (jf the 

 thigh l)one witli the rim of the acetabulum, Hexion of the thigh so far as the joint 

 is concerned is practically unlimited. Flexion is the most important, most fre- 

 quent, and most extensive movement, and in the dissected limb, Ijefore the liga- 

 ments are disturbed, can be carried to 160°, and is then checked by the lower fibres 

 of the ischio-femoral ligament. In the living subject simple flexion can continue 

 until checked by the contact of the soft parts at the groin, if the knee be bent; if 

 the knee be straight, flexion of the hip is checked in most persons by the hamstring 

 muscles at nearly a right angle. This is very evident on trying to touch the ground 



Fig. 243.— Ligamentum Teres, very lax in complete Extension. 



with the fingers without bending the knees, the chief strain being felt at the pop- 

 liteal space Til is is due to the shortness of the hamstrings. Extension is limited 

 by the ilio-fcmoral ligament. 



Al)duction and outward rotation can be performed freely in every position of 

 flexion and extension — abduction being limited by the pectineo-femoral ligament; 

 outward rotation by the ilio-femoral ligament, especially its inner portion, during 

 extension; but by ithe outer portion, as well as by the ligamentum teres, during 

 flexion. 



Adduction is very limited in the extended thigh on account of the contact with 

 the opposite liml). In the slightly flexed position adduction is more free than in 

 extension, and is then limited by tlie outer fil)res of the ilio-femoral band and the 

 su})erior portion of the ca])sule. In flexion the range is still greater, and limited 

 l)y the ischio-femoral ligament, the ligamentum teres being also rendered nearly 

 tight. Inward rotation in the nearly extended position is limited by the ilio- 

 femoral ligament; and in flexion by the ischio-femoral ligament and the portion of 

 the capsule between it and the ilio-femoral band. 



