Scaphoid

The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid bone is the largest bone of the proximal row of wrist bones, its long axis being from above downward, lateralward, and forward. It is approximately the size and shape of a medium cashew. The scaphoid articulates with five bones: the radius, trapezium, trapezoid, capitate, and lunate. Surfaces The superior surface is convex, smooth, of triangular shape, and articulates with the lower end of the radius. The inferior surface, directed downward, backward, and laterally, is also smooth, convex, and triangular, and is divided into two parts by a slight ridge, the lateral articulating with the greater multangular, the medial with the lesser multangular. On the dorsal surface is a narrow, rough groove which runs the entire length of the bone and serves for the attachment of ligaments. It contributes to the floor of the anatomical snuff box where a branch of the radial artery crosses over it. A ligament, the dorsal radiocarpal, attaches to this surface. The volar surface is concave above, and elevated at its lower and lateral part into a rounded projection, called the tubercle, which is directed forward and gives attachment to the transverse carpal ligament and sometimes origin to a few fibers of the abductor pollicis brevis. The lateral surface is rough and narrow and gives attachment to the radial collateral ligament of the wrist. The medial surface presents two articular facets; of these, the superior or smaller is flattened, of semilunar form, and articulates with the lunate bone; the inferior or larger is concave, forming with the lunate a concavity for the head of the capitate bone. The distal convex surface articulates with the trapezium and trapezoid.

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