ao2 



THE ARTICULATIONS. 



Fig. 130. 



supercarpal bone to the first bone of the inferior row and to the head of the 

 external metacarpal bone. 



b. The internal lateral ligament (Fig. 129, 4), analogous to the preceding 



and situated on the opposite side, is wider and thicker than it. It commences on 



the internal tuberosity of the radius, and terminates on the upper extremity of 



the middle and internal metacarpal bones, after being attached, by two distinct 



fasciculi, to the third carpal bone of the upper row, and 



the two last of the metacarpal row. In contact by its 



external face with the tendon of the oblique extensor muscle 



of the metacarpus, this ligament responds, by its deep face, 



to the synovial membranes of the carpus and to the bones 



to which it is attached. By its anterior border it is united 



to the capsular ligament ; the opposite border is intimately 



confounded with the posterior ligament, from wliich it is 



impossible to distinguish it. 



c. The anterior, or capsular ligament, is a membranous 

 band covering the anterior face of the carpal articulations. 

 Its superior border is attached to the radius ; the inferior 

 is inserted into the superior extremity of the principal 

 metacarpal bone. The two right and left borders are 

 united with the lateral ligaments. Its external face is in 

 contact with the tendons of the anterior extensor muscles 

 of the metacarpus and phalanges. The internal face is 

 lined at certain points by synovial membrane, and adheres 

 in others to the carpal bones and the anterior ligaments 

 binding these to one another. This ligament is composed 

 of transverse fibres more or less oblique, and arranged cross- 

 wise ; by its amplitude it can adapt itself to the movements 

 of flexion of the knee. 



d. The posterior ligament, one of the strongest in the 

 animal economy, covers the posterior face of the carpus, 

 filling up the asperities which roughen it. It is inserted : 

 above, on the transverse crest surmounting the articular 

 surface of the radius ; by its middle portion into all the 

 carpal bones ; below, into the head of the principal meta- 

 carpal bone. Confounded inwardly with the internal 

 lateral ligament, united outwardly to the band which at- 

 taches the supercarpal to the external metacarpal and the second carpal bone of 

 the upper row, this ligament is continued, by its inferior extremity, with the carpal 

 stay (or check ligament) which sustains the perforans tendon. Its posterior face 

 is perfectly smooth, and is covered by the synovial membrane of the carpal 

 sheath. 



Movements of thf Carpal Articulations. — The carpus is the seat of 

 two very extensive and opposite movements— flexion and extension; to wliich 

 are added three very limited accessory movements — adduction, abduction, and 

 circumduction. 



All the carpal articulations do not take an equal part in the execution of 

 these movements ; for it is easy to discover that they are chiefly performed in the 

 radio-carpal diarthrosis, and in the imperfect hinge articulation uniting the two 

 rows of carpal bones. Each of these articulations participates in the movements 



LATERAL VIEW OF THE 

 CARPAL ARTICOLATIONS. 



1, 1, Anterior ligaments 

 uniting the two rows 

 of carpal bones; 2, 2, 

 anterior ligaments pro- 

 per to the carpo-meta- 

 carpal articulation ; 3, 

 common external liga- 

 ment; 4, one of the 

 ligaments proper to the 

 articulation of the two 

 rows (metacarpo-supra- 

 carpal) ; 5, one of the 

 ligaments proper to 

 the radio-carpal articu- 

 lation (radio-supercar- 

 pal). A, Groove on the 

 external surface of the 

 supercarpal bone, for 

 the passage of the ex- 

 ternal flexor of the 

 metacarpus. 



