The scaphoid is the largest carpal bone of the proximal row. It is found at the radial end of the row, sitting at the base of the thumb. The scaphoid links the hand with the forearm, articulating with the radius proximally at the radiocarpal (wrist) joint.

The scaphoid is also known as the navicular bone of the wrist, as it has a boat-shaped appearance. Moreover, its name comes from the Greek skaphos, which means “boat.”

Almost 75% of its surface is covered by articular cartilage. Besides the radius, it also articulates with the lunate bone and capitate bone medially and trapezium bone and trapezoid bone distally. Therefore, it has the following five articular surfaces:

Articular surface for radius - smooth and convex; directed proximally;
Articular surface for lunate - relatively flat, narrow, and semilunar-shaped;
Articular surface for capitate - deeply concave; directed medially and distally;
Articular surface for trapezoid - convex and directed distally;
Articular surface for trapezium - convex and directed distally.

Adjacent to the articular surface for the capitate, the scaphoid has a blunt, nonarticular, rounded projection known as the tubercle. It is found on the palmar aspect of the bone and serves as one of the attachment sites for the flexor retinaculum of the wrist, forming the radial portion of the carpal tunnel.

Some fibers of the abductor pollicis brevis muscle attach to the tubercle. Also, several ligaments insert on the scaphoid, including the radioscaphocapitate ligament, scapho-trapezio-trapezoid ligament, radial carpal collateral ligament, and radioscapholunate ligament.

Additionally, lateral to the attachment site of the flexor retinaculum, the scaphoid may have a very shallow groove that can be left by the tendon of the flexor carpi radialis muscle.

Note: The scaphoid is the most commonly fractured bone among the carpal bones. This bone tends to break during a fall onto the outstretched hand. A common complication of fractured scaphoid is post-traumatic avascular necrosis due to the limited blood supply the bone receives at its proximal aspect. The blood vessels enter the bone at its distal portion.

Note: 3D model displays the left scaphoid.

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Scaphoid