Hand Bones

There are 27 bones in each human hand, with the total number being 54. These bones, along with the muscles and ligaments in the region, give structure to the human hand and allow for all the movement and dexterity of the hands and fingers. There are three major types of bones in hand, based on their location and purpose.

Carpal Bones

The human wrist comprises 8 uniquely-shaped irregular bones arranged in two rows, with the first four in the proximal row and the next four in the distal row. Here are their names:

1. Scaphoid
2. Lunate
3. Triquetrum
4. Pisiform
5. Trapezium
6. Trapezoid
7. Capitate
8. Hamate

Together, these bones connect the lower arm to the hand and fingers as the proximal carpal bones articulate with the radius and ulna to form the wrist joint.

These bones articulate with each other, allowing wrist movement so we can perform common daily activities with our hands.

Metacarpal Bones

These bones form the middle part, the back of the hand or palm area. There are 5 metacarpal bones in the human body, with each of these long bones having a base, shaft, and head.

Their proximal end articulates with the distal row of carpal bones. The first to the fifth metacarpal is associated with the respective finger, from the thumb to the little finger. The distal end of each metacarpal articulates with the proximal phalanx in each finger.

Phalanges

There are 7 bones forming the fingers in each hand.

Based on their location, they are referred to as:

• Proximal phalanx
• Middle phalanx
• Distal phalanx

The index to little finger have 3 phalanges each, while only two are in each thumb.

Joints and Articulations

Radiocarpal joint: Between the radius and the carpals

Ulnocarpal Joint: Where the carpals articulate with the ulna.

The above two articulations, together with the distal radioulnar joint (between the radius and ulna) form the wrist.

Carpometacarpal (CMC) Joints: Between the carpals and the metacarpal bone. The CMC joint of the thumb has the greatest range of motion.

Metacarpophalangeal (MP) Joint: Between the metacarpals and the proximal phalanges in each finger.

Interphalangeal (IP) Joints: Between the proximal, middle, and distal phalanges. All the fingers except the thumb have one proximal and one distal interphalangeal joint. The thumb only has a single joint between its two phalanges.