Which carpal bones are in the proximal row

Though we often speak of it as one joint, there are really two joints here, very close together. Eight small carpal bones form the carpus. Distal to the carpus are the metacarpal bones, numbered one, two, three, four and five. The carpal bones are in two rows, a proximal and a distal. The bones in each row are attached closely to one another. The four bones of the proximal row are the scaphoid, the lunate, the triquetral, and the pisiform, which sits by itself on the triquetral. The scaphoid, the lunate and part of the triquetral articulate with the distal end of the radius, to form the radio-carpal joint.

The distal surface of the proximal row forms a deeply concave notch, which the bones of the distal row fit into. The bones of the distal row are the trapezium, the trapezoid, the capitate, and the hamate.

The capitate and part of the hamate project proximally. The bases of the five metacarpals articulate with the distal row of carpal bones. The first, the one for the thumb, articulates by itself with the trapezium. The other four articulate in a row, here. The distal row of carpal bones articulates with the proximal row here, to form the midcarpal joint. The projecting capitate and hamate fit into the notch in the proximal row.

When flexion and extension occur at the wrist, the movement happens partly at the radiocarpal joint ,and partly at the midcarpal joint. When radial deviation and ulnar deviation occur, the action happens mainly at the radio-carpal joint.

The radial collateral ligament goes from the radial styloid to the scaphoid and its neighbor, the trapezium. The ulnar collateral ligament goes from the ulnar styloid, to the triquetral and pisiform bones. The joint capsule is thick and strong all the way round the joint. On the extensor aspect, the capsule forms the broad dorsal radiocarpal ligament. On the flexor aspect it forms the palmar radiocarpal ligament.

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Verify now. Toggle navigation. Institutional subscriptions support Language. Keep me signed in. Forgot your password? Sign in with Facebook. Sign in with Apple. Description The carpal bones, eight in number, are arranged in two rows. This definition incorporates text from a public domain edition of Gray's Anatomy 20th U.