The carpal bones in the proximal row from medial to lateral are the pisiform, triquetral, lunate and the scaphoid bones. The proximal and distal rows make up the carpus, which is the area between the metacarpals and the distal ends of the radius and ulna, or the wrist.Continue Reading
The proximal row is convex proximally and concave distally. Each bone has six surfaces: one palmar, one dorsal, two lateral and two medial.
The pisiform bone is pea-shaped and has a single oval facet on the proximal part of its dorsal surface where the triquetral bone lies.The triquetral is pyramidal in shape and has an oval facet on the distal part of the palmar surface. The medial and dorsal surfaces are continuous and nonarticular.
The lunate, or semilunar bone, is half-moon or crescent shaped. It has a small semilunar articular surface for the scaphoid bone on the lateral side and a quadrilateral articular surface for the triquetral on the medial side. The lunate has a convex and smooth surface and articulates with the radius.
The scaphoid is the largest bone in the proximal row. It is boat-shaped and approximately the size of a cashew. The scaphoid has a tubercle on its lateral side that aims laterally, forwards and downwards.Learn more about Bones