Full Hand and Wrist Description
[Continued from above] . . . into the wrist.
At the lower end of the larger forearm bone (ulna), its knob-like head articulates with a notch of the radius (ulnar notch) laterally and with a disk of fibrocartilage below. This disk, in turn, joins a wrist bone (the triquetrum). A medial styloid process at the lower end of the ulna provides attachments for ligaments (palmar ulnocarpal ligament and dorsal ulnocarpal ligament) into the wrist.
There are eight small carpal bones in the wrist that are firmly bound in two rows of four bones each. The mass that results from these bones is called the carpus. The carpus is rounded on its nearest surface, where it articulates with the radius and with the fibrocartilaginous disk on the ulnar side. The carpus is rounded convexly in the front, forming a canal (retinaculum) through which tendons, ligaments, and nerves extend to the palm. Its distal surface articulates with the metacarpal bones, which are joined to the carpus by the palmar carpometacarpal ligaments.