218 ARTICULATIONS. 



The Anterior or Palmar Ligaments consist of short fibres, which pass obliquely 

 between the bones of the first and second row on the palmar surface. 



The Posterior or Dorsal Ligaments have a similar arrangement on the dorsal 

 surface of the carpus. 



The Lateral Ligaments are very short ; they are placed, one on the radial, the 

 other on the ulnar side of the carpus ; the former, the stronger and more distinct, 

 connecting the scaphoid and trapezium bones, the latter the cuneiform and unci- 

 form : they are continuous with the lateral ligaments of the wrist-joint. 



There are two Synovial Membranes found in the articulation of the carpal 

 bones with each other. The first of these, the more extensive, lines the under 

 surface of the scaphoid, semilunar, and cuneiform bones, sending upwards two 

 prolongations between their contiguous surfaces; it is then reflected over the 

 bones of the second row, and sends down three prolongations between them, which 

 line their contiguous surfaces, and invest the carpal extremities of the four outer 

 metacarpal bones. The second is the synovial membrane between the pisiform 

 and cuneiform bones. 



Actions. The partial movement which takes place between the bones of each 

 row is very inconsiderable ; the movement between the two rows is more marked, 

 but limited chiefly to flexion and extension. 



9. CARPO-METACAEPAL ARTICULATIONS. 



ARTICULATION OF THE METACARPAL BONE OF THE THUMB WITH THE TRAPEZIUM. 



This is an enarthrodial joint. Its ligaments are a capsular and synovial mem- 

 brane. The capsular ligament is a thick but loose capsule, which passes from 

 the circumference of the upper extremity of the metacarpal bone, to the rough 

 edge bounding the articular surface of the trapezium ; it is thickest externally 

 and behind, and lined by a separate synovial membrane. 



ARTICULATION OF THE METACARPAL BONES OF THE FINGERS WITH THE CARPUS. 



The joints formed between the carpus and four inner metacarpal bones are 

 connected together by dorsal, palmar, and interosseous ligaments. 



The Dorsal Ligaments, the strongest and most distinct, connect the carpal and 

 metacarpal bones on their dorsal surface. The second metacarpal bone receives 

 two fasciculi, one from the trapezium, the other from the trapezoid ; the third 

 metacarpal receives one from the os magnum ; the fourth two, one from the os 

 magnum, and one from the unciform ; the fifth receives a single fasciculus from 

 the unciform bone. 



The Palmar Ligaments have a somewhat similar arrangement on the palmar 

 surface, with the exception of the third metacarpal, which has three ligaments, an 

 external one from the trapezium, situated above the sheath of the tendon of the 

 Flexor carpi radialis ; a middle one, from the os magnum ; and an internal one, 

 from the unciform. 



The Interosseous Ligaments consist of short thick fibres, which are limited to 

 one part of the carpo-metacarpal articulation ; they connect the contiguous inferior 

 angles of the os magnum and unciform, with the adjacent surfaces of the third 

 and fourth metacarpal bones. 



The Synovial Membrane is a continuation of that between the two rows of 

 carpal bones. Occasionally, the articulation of the unciform with the fourth 

 and fifth metacarpal bones has a separate synovial membrane. 



The Synovial Membranes of the wrist (fig. 136) are thus seen to be five in 

 number. The first, the membrana sacciformis, lining the lower end of the ulna, 

 the sigmoid cavity of the radius, and upper surface of the triangular interarticular 

 fibro-cartilage. The second lines the lower end of the radius and interarticular 

 fibro-cartilage above, and the scaphoid, semilunar, and cuneiform bones below. The 

 third, the most extensive, covers the contiguous surfaces of the two rows of carpal 



