OF THE CARPUS. 263 



The Arteries supplying the Joint are the anterior and posterior carpal branches 

 of the radial and ulnar, the anterior and posterior interosseous, and some ascending 

 branches from the deep palmar arch. 



The Nerves are derived from the ulnar and posterior interosseous. 



Actions. The movements permitted in this joint are flexion, extension, abduc- 

 tion, adduction, and circumduction. Its actions will be further studied with those 

 of the carpus, with which they are combined. 



Surface Form. The line of the radio-carpal joint is on a level with the apex of the styloid 

 process of the ulna. 



Surgical Anatomy. The wrist-joint is rarely dislocated, its strength depending mainly 

 upon the numerous strong tendons which surround the articulation. Its security is further pro- 

 vided for by the number of small bones of which the carpus is made up, and which are united 

 by very strong ligaments. The slight movement which takes place between the several bones 

 serves to break the jars that result from falls or blows on the hand. Dislocation backward, 

 which is the more common, simulates to a considerable extent Colles' fracture of the radius, and 

 is liable to be mistaken for it. The diagnosis can be easily made out by observing the 

 relative position of the styloid processes of the radius and the ulna. In the natural condition the 

 styloid process of the radius is on a lower level i. e. nearer the ground when the arm hangs by 

 the side, than that of the ulna, and the same would be the case in dislocation. In Colles' frac- 

 ture, on the other hand, the styloid process of the radius is on the same, or even a higher level 

 than that of the ulna. 



The wrist-joint is occasionally the seat of acute synovitis, the result of traumatism or arising 

 in the rheumatic or pyaemic state. When the synovial sac is distended with fluid, the swelling 

 is greatest on the dorsal aspect of the wrist, showing a general fulness, with some bulging between 

 the tendons. The inflammation is prone to extend to the intercarpal joints and to attack also 

 the sheaths of the tendons in the neighborhood. Chronic inflammation of the wrist is generally 

 tubercular, and often leads to similar disease in the synovial sheaths of adjacent tendons and of 

 the intercarpal joints. The disease, therefore, when progressive, often leads to necrosis of the 

 carpal bones, and the result is often unsatisfactory. 



VIII. Articulations of the Carpus. 



These articulations may be subdivided into three sets: 



1. The Articulations of the First Row of Carpal Bones. 



2. The Articulations of the Second Row of Carpal Bones 



3. The Articulations of the Two Rows with each other. 



1. ARTICULATIONS OF THE FIRST Row OF CARPAL BONES. 



These are arthrodial joints. The ligaments connecting the scaphoid, semilunar, 

 and cuneiform bones are 



Dorsal. Palmar. 



Two Interosseous. 



The Dorsal Ligaments are placed transversely behind the bones of the first 

 row ; they connect the scaphoid and semilunar and the semilunar and cuneiform. 



The Palmar Ligaments connect the scaphoid and semilunar and the semilunar 

 and cuneiform bones ; they are less strong than the dorsal, and placed very deeply 

 below the anterior ligament of the wrist. 



The Interosseous Ligaments (Fig. 177) are two narrow bundles of fibrous 

 tissue connecting the semilunar bone on one side with the scaphoid, and on the 

 other with the cuneiform. They are on a level with the superior surfaces of these 

 bones, and close the upper part of the spaces between them. Their upper surfaces 

 are smooth, and form with the bones the convex articular surfaces of the wrist- 

 joint. 



The ligaments connecting the pisiform bone are 



Capsular. Two Palmar ligaments. 



The Capsular Ligament is a thin membrane which connects the pisiform bone 

 to the cuneiform. It is lined with a separate synovial membrane. 



The two Palmar Ligaments are two strong fibrous bands which connect the 



