Each human hand contains 27 bones, adding up to a total of 54 bones. These skeletal components, in conjunction with the muscles and ligaments in the area, provide framework to the human hand and enable all the mobility and agility of the hands and fingers. The hand comprises three main categories of bones, categorized based on their location and function.
Carpal Skeleton
The human wrist is composed of 8 distinctly-shaped irregular bones arranged in two rows, with the initial four in the proximal row and the subsequent four in the distal row. Here are their designations:
- Scaphoid
- Lunate
- Triquetrum
- Pisiform
- Trapezium
- Trapezoid
- Capitate
- Hamate
These bones collectively link the lower arm to the hand and fingers as the proximal carpal bones connect with the radius and ulna to establish the wrist joint.
These bones articulate with one another, facilitating wrist movement essential for performing daily activities with our hands.
Metacarpal Framework
These bones constitute the middle segment, the back of the hand, or the palm region. There are 5 metacarpal bones in the human body, each of these elongated bones possessing a base, shaft, and head.
Their proximal end connects 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 connects with the proximal phalanx in each finger.
Finger Phalanx
There are 7 bones constituting the digits in each hand.
Based on their location, they are known 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 Connectors
Radiocarpal joint: Between the radius and the carpals
Ulnocarpal Joint: Where the carpals connect with the ulna.
The above two interconnections, along 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.
References
- Anatomy of the Hand – Hopkinsmedicine.org
- Bones of the Hand: Carpals, Metacarpals and Phalanges – Teachmeanatomy.info
- Hand and wrist bones – Mayoclinic.org
- Anatomy: Hand and Wrist – Bidneedham.org
