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In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; [1] [2] (2) the wrist joint or radiocarpal joint, the joint between the radius and the carpus [2] and; (3) the anatomical region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of ...
Joints of the hand, X-ray. The bones in each carpal row interlock with each other and each row can therefore be considered a single joint. In the proximal row a limited degree of mobility is possible, but the bones of the distal row are connected to each other and to the metacarpal bones by strong ligaments that make this row and the metacarpus a functional entity.
The proximal row comprises the scaphoid, lunate, triquetral, and pisiform bones which articulate with the surfaces of the radius and distal carpal row, and thus constantly adapts to these mobile surfaces. Within the proximal row, each carpal bone has slight independent mobility.
The scaphoid is situated between the proximal and distal rows of carpal bones. It is located on the radial side of the wrist, [1]: 176 adjacent to the styloid process of the radius. [2] It articulates with the radius, lunate, trapezoid, trapezium, and capitate. [1]: 176 Over 80% of the bone is covered in articular cartilage. [3]
Anatomically, the proximal and distal interphalangeal joints are very similar. There are some minor differences in how the palmar plates are attached proximally and in the segmentation of the flexor tendon sheath, but the major differences are the smaller dimension and reduced mobility of the distal joint. [1]
Thus the upper arm in humans is proximal and the hand is distal. "Proximal and distal" are frequently used when describing appendages, such as fins, tentacles, and limbs. Although the direction indicated by "proximal" and "distal" is always respectively towards or away from the point of attachment, a given structure can be either proximal or ...
The proximal surface of the lunate bone is smooth and convex, articulating with the radius. The lateral surface is flat and narrow, with a crescentic facet for articulation with the scaphoid bone. The medial surface possesses a smooth and quadrilateral facet for articulation with the triquetral bone. The palmar surface is rough, as is the ...
The cavity of the midcarpal joint is very extensive and irregular. The major portion of the cavity is located between the distal surfaces of the scaphoid, lunate, and triquetrum and proximal surfaces of the four bones of the distal row. Proximal prolongations of the cavity occur between the scaphoid and lunate and between the lunate and triquetrum.