THE HIP-JOINT. 



365 



though differing from it in having no nests of cartilage-cells amongst its fibres. 

 It consists of strong, flattened fibres, which cross the notch at the lower part of the 

 acetabulum and convert it into a foramen. Thus an interval is left beneath the 

 ligament for the passage of nutrient vessels to the joint. 



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- 



ligament 





RECT. FEM. 



Ileo-fem. ligament 



Pub. fern, ligament 



FIG. 256. 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. 



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

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

 head of the Rectus and Glutens 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 

 Qnadratus femoris (Fig. 256). 



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



umflex. 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, like those of all enarthrodial joints, are 

 very extensive ; they are flexion, extension, adduction, abduction, circumduction, 

 and rotation. 



The hip-joint presents a very striking contrast to the other great enarthrodial 

 joint the shoulder in the much more complete mechanical arrangements for its 

 security and for the limitation of its movements. In the shoulder, as we have seen, 

 the head of the humerus is not adapted at all in shape to the glenoid cavity, and is 



