THE HIP-JOIXT 



251 



The arterial supply comes from (a) the transverse branches of the mternal 

 and external circumtlex arteries; (6) the external brancli of the obturator sends a 

 Vjranch through the cotyloid notch beneath the transverse ligament, which ramifies 

 in the fat at the bottom of the acetabulum, and travels down the round ligament 

 to the head of the femur; (c) the inferior branch of the deep division of the gluteal; 

 and {(1) the sciatic arteries. The branch from the obturator to the ligamentum 

 teres is sometimes very large when the branch from the internal circumflex does 

 not also supply the ligament. 



The gluteal and sciatic send several branches through the innominate attach- 

 ment of the capsular ligament : 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 cotyloid ligament. 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 cotyloid ligament. 



The nerve-supply comes from (a) anterior crural, {h) anterior division of the 

 obturator, (c) the accessory obturator, and (dl) 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. 



The muscles in relation with the hip-joint are: in front, the psoaf<, which is 



Fig. 242. — Ligamentum Teres, lax i.v Flexiox. 



separated from the capsule by a bursa, and the iliacus, which in part arises from 

 the capsule; above are the straight and reflected tendons of the rectii.s:^ the reflected 

 tendon being enclosed between the fibres of the capsule, and a band which passes 

 down from the reflected tendon to the vastus extemus; also the gluteus minimus, 

 which is closely adherent to the capsule; above and Jaehind are the piriformis, 

 which sometimes sends a slip into the capsule; the internal obturator, which acts as 

 a powerful .strap to the back of the joint, and the two gemelli ; below and behind 

 is the external obturator, passing over the capsule, whilst a dense band of filjro- 

 cellular tissue connects the sheath of the o1>turator externus with the capsule along 

 the posterior edgi- of the nmscle; internally is the pedineus. 



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

 but with a much more complete socket and a corresjjonding limitation of move- 

 ment. Each variety of movement is permitted, \\z. flexion, extension, abduction, 

 adduction, circumduction, and rotation; 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. 



It results from the o1)liquity of the neck of the femur that the movements of 

 the head in the acetabulum are always more or less of a rotatory character. This 

 is more especially the case during flexion and extension, and two results follow 



