282 



THE ARTICULATIONS 



The synovial membrane lines the capsule and both surfaces of the glenoid 

 lip, and passes over the border of the acetabulum to reach and cover the fatty 

 cushion it contains. The part covering the fatty cushion is unusually thick, and 

 is attached round the edges of the rough bony surface on which the cushion rests. 

 The membrane is loosely reflected off this on to the ligamentum teres, along 

 which it is prolonged to the head of the femur; thus the fibres of the round liga- 

 ment are shut out from the joint cavity. From the capsule the synovial mem- 

 brane is also reflected below on to the neck of the femur, whence it passes over 

 the retinacula to the margin of the articular cartilage. A fold of synovial mem- 

 brane on the under aspect of the neck often conveys to the head of the femur a 

 branch of an artery — generally a branch of the medial circumflex. 



The arterial supply comes from — (o) the transverse branches of the medial and lateral 

 circumflex arteries; (b) the lateral branch of the obturator sends a branch through the acetabular 

 notch beneath the transverse ligament, which ramifies in the fat at the bottom of the ace- 

 tabulum, and travels down the round ligament to the head of the femur; (c) the inferior branch of 

 the deep division of the superior gluteal; and (d) the inferior gluteal (sciatic) arteries. The 

 branch from the obturator to the ligamentum teres is sometimes very large when the branch 

 from the medial circumflex does not also supply the ligament. 



' The superior and inferior gluteal send several branches through the innominate attachment 



Fig. 313. — Ligamentum Teres, lax in Flexion. 



of the articular capsule: these anastomose freely beneath the capsule around the outer aspect 

 of the acetabulum, and supply some branches to enter the bone, and others which enter the 

 substance of the glenoid lip. There is quite an arterial crescent upon the posterior and postero- 

 superior portions of the acetabulum; but no vessels are to be seen on the inner aspect of the 

 glenoid lip. 



The nerve-supply comes from — (a) femoral (anterior crural), (b) anterior division of the 

 obturator, (c) the accessory obturator, and (d) the sacral plexus, by a twig from the nerve to 

 the quadratus femoris, or from the upper part of the great sciatic, or from the lower part of the 

 sacral plexus. 



Relations. — In front and in contact with the capsule are the psoas bursa, the tendinous 

 part of the psoas magnus, and the iliacus. Still more anteriorly and not in contact are the 

 femoral artery, the femoral (anterior crural) nerve, the rectus femoris, the sartorius, and the 

 tensor fascia; latie. 



Above and in close relation with the capsule are the piriformis, the obturator intern us and 

 the gemelli, and the reflected head of the rectus femoris, whilst more superficially lie the gluteus 

 minimus and medius. 



Behind and in close relation with the capsule are the obturator oxternus, the gemelli and 

 obturator internus, and the piriformis. More superficially lie the quadratus femoris, the sciatic 

 nerves, and the gluteus maxiinus. 



Below the oljtiirator oxternus, the pectineus, and the medial circumflex artery are in close 

 relation with the capsule. 



The movements.— The hip-joint, like the shoulder, is a ball-and-socket joint, but with a 

 much more complete socket and a corresponding limitation of movement. Each variety of 

 movement is permitted, viz., flexion, extension, abduction, adduction, circumduction, and rota- 

 tion; and any two or more of these movements not being antagonistic can be combined, i. e., 

 flexion or extension associated with abduction or adduction can be combined with rotation in 

 or out. 



