THE HIP-JOINT 141 



carpus and four inner metacarpals have dorsal, plantar, and 

 interosseous ligaments. 



The synovia! membranes of all the joints in the carpus and 

 wrist proper are five in number (Fig. 24). 



The Remaining Ligaments of the Metacarpus and 



Phalanges 



Of the metacarpals with each other, there are the dorsal, 

 palmar, and interosseous ligaments; their digital extremities 

 are connected by a narrow band, the transverse ligament, 

 presenting four grooves for tendons. 



The metacarpophalangeal articulations have anterior and two 

 lateral ligaments. The interphalangeal articulations also have 

 anterior and two lateral ligaments. 



Actions are flexion, extension, and very limited abduction, 

 adduction and circumduction. 



ARTICULATIONS OF THE LOWER EXTREMITY 



The Hip- joint 



It is an enarthrodial or ball-and-socket joint. The articular 

 surface of the head of the femur is more than a hemisphere; 

 any section of the bony acetabulum through its centre is less 

 than 180 degrees. 



The ligaments are cotyloid, transverse, teres, capsular; 

 accessory are orbicular zone, iliofemoral, iliotrochanteric, pubo- 

 femoral, ischiofemoral, and ischiocapsular . 



The cotyloid consists of connective tissue arranged circularly; 

 it is strengthened and fastened to the edge of the acetabulum 

 by short fibers rising at different points and interlacing at 

 acute angles. It is prismoid on section, and embraces the 

 head of the femur so tightly that air does not enter the joint. 

 Both its sides are covered with synovial membrane. Inferiorly 

 the cotyloid becomes flat and bridges over the acetabular 

 notch at the transverse ligament; it turns one surface upward 

 and one down; one edge looks within and limits a split through 

 which, enveloped in fat, bloodvessels enter the socket; the 

 other edges pass uninterruptedly into the cotyloid ligament. 



