THE HIP-JOINT. 



271 



The Synovial Membrane is very extensive. Commencing at the margin of the 

 cartilaginous surface of the head of the femur, it covers all that portion of the 

 neck which is contained within the joint; from the neck it is reflected on the 

 internal surface of the capsular ligament, covers both surfaces of the cotyloid liga- 

 ment and the mass of fat contained in the depression at the bottom of the acetab- 



Isch. caps, ligament 



RECT. FEM. 



Ileo-fem. ligament 



Pub. fern, ligament 



Fia. 182. Relation of muscles to hip-joint. (Henle.) 



ulum, and is prolonged in the form of a tubular sheath around the ligamentum 

 teres, as far as the head of the femur. It sometimes communicates through a 

 hole in the capsular ligament between the inner band of the Y-shaped ligament 

 and the pubo-femoral ligament with a bursa situated on the under surface of the 

 Ilio-psoas muscle. 



The muscles in relation with the joint are, in front, the Psoas and Iliacus, 

 separated from the capsular ligament by a synovial bursa ; above, the reflected 

 head of the Rectus and Gluteus minimus, the latter being closely adherent to the 

 capsule ; internally, the Obturator externus and Pectineus ; behind, the Pyriformis, 

 Gemellus superior, Obturator internus, Gemellus inferior, Obturator externus, and 

 Quadratus femoris (Fig. 182). 



The arteries supplying the joint are derived from the obturator, sciatic, internal 

 circumflex, and gluteal. 



The nerves are articular branches from the sacral plexus, great sciatic, obtu- 

 rator, accessory obturator, and a filament from the branch of the anterior crural 

 supplying the Rectus. 



Actions. The movements of the hip are very extensive, and consist of 

 flexion, extension, adduction, abduction, circumduction, and rotation. 



The hip-joint presents a very striking contrast to the shoulder-joint in the 

 much more complete mechanical arrangements for its security and for the limita- 

 tion of its movements. In the shoulder, as we have seen, the head of the 

 humerus is not adapted at all in size to the glenoid cavity, and is hardly re- 

 strained in any of its ordinary movements by the capsular ligament. In the hip- 

 joint, on the contrary, the head of the femur is closely fitted to the acetabulum 



