254 INFERIOR EXTREMITY 



Movements permitted at the Hip -joint. Before the capsule of the 

 joint is opened the range of movement which is permitted at the hip-joint 

 should be tested. Flexion, or forward movement, is very free, and is only 

 checked by the anterior surface of the thigh coming into contact with the 

 abdominal wall. Extension, or backward movement, is limited by the 

 ilio-femoral ligament. This powerful ligament has a most important part to 

 play in preserving the upright attitude with the least possible expenditure 

 of muscular exertion. In the erect posture the line of gravity falls slightly 

 behind the line joining the central points of the two hip-joints. In the 

 upright attitude the ilio-femoral ligaments are tense, and prevent the pelvis 

 from rolling backwards on the heads of the femora. Abdiiction, or lateral 

 movement of the limb, is checked by the pubo-femoral ligament. Adduction, 

 or medial movement (e.g. as in crossing one thigh over the other), is limited 

 by the proximal portion of the ilio-femoral ligament and the proximal part 

 of the capsule. Rotation medially tightens the ischio-capsular ligament, and 

 is therefore in a measure restrained by it. Rotation laterally is limited by 

 the lateral portion of the ilio-femoral ligament. In circumduction, which 

 is produced by combination of the movements of flexion, abduction, exten- 

 sion, and adduction, different parts of the capsular ligament are tightened 

 at different stages of the movement. 



The flexor muscles, which operate on the femur at the hip-joint, are 

 chiefly (i) the ilio-psoas, and (2) the pectineus ; the extensors are (i) 

 the glutams maximus, and (2) the gluteus medius ; (3) the hamstrings ; 

 the abductors (i) the upper part of the glutceus maximus, (2) the glutieus 

 medius, (3) the glutreus minimus; the addiictors (i) the three adductors, 

 (2) the pectineus, (3) the distal part of the glutreus maximus, and (4) the 

 obturator externus ; the medial rotators ( I ) the anterior part of the glutteus 

 medius, (2) the anterior part of the glutaeus minimus, (3) the tensor fascioe 

 latse, and (4) the ilio-psoas; the lateral rotators (i) the two obturator 

 muscles, (2) the gemelli, (3) the piriformis, (4) the quadratus femoris, and 

 (5) the distal fibres of the glutaeus maximus. 



It should be noted that the muscle fibres which act as lateral rotators 

 when the body is erect, become abductors when the hip-joint is flexed, 

 and that the ilio-psoas is a flexor of the hip-joint and a medial rotator of 

 the thigh until flexion is almost complete, but then it becomes a lateral 

 rotator. 



Dissection. The hip-joint may now be opened, and in doing this it is 

 advisable to remove in the first instance the whole capsule, with the 

 exception of the ilio-femoral ligament. The enormous strength of this portion 

 of the capsule can in this way be appreciated. It is fully a quarter of an 

 inch thick, and a strain varying from 250 Ibs. to 750 Ibs. is required for 

 its rupture (Bigelow). It is very rarely torn asunder in dislocations, and 

 consequently the surgeon is enabled in most cases to reduce the displace- 

 ment by manipulation. The ilio-femoral ligament may now be removed. 



Labrum Glenoidale (O.T. Cotyloid Ligament). This is a 

 firm fibre-cartilaginous ring, which is fixed to the brim or margin 

 of the acetabulum. It bridges across the incisura, and thus com- 

 pletes the circumference of the cavity, deepens it, and at the 

 same time narrows slightly its mouth. The labrum glenoidale 

 fits closely upon the head of the femur, and, acting like a 

 sucker, exercises an important influence in retaining it in 

 place. Both surfaces of the labrum are covered by synovial 



