In Depth: Bones
The ends of the radius and ulna bones come together at the hand to form the wrist, which is formally known as the carpus. Together with the bones of the palm, these bones form two rows: the distal row, closest to the palm, and the proximal row, closest to the forearm.
The eight bones of the wrist are:
- Scaphoid: This bone is on the thumb side of the hand near the radius.
- Lunate: This bone rests between the scaphoid and triquetrum in the proximal row.
- Triquetrum: This small bone is on the pinkie side of the hand.
- Pisiform: This small bone is on the palm side of the triquetrum.
- Trapezium: This bone rests between the scaphoid and the metacarpal of the thumb.
- Trapezoid: The smallest bone in the distal row, this sits between the trapezium and the capitate.
- Capitate: The largest of the wrist bones, this sits between the trapezoid and the hamate behind the middle and ring fingers.
- Hamate: This small bone has a hook on the palm side. It rests next to the capitate on the pinkie side of the wrist.
The wrist bones connect to the hand’s metacarpal bones. These are the largest bones of the hand. The ends of these five bones touch the wrist and create the skeletal structure for the palm. The metacarpals are numbered one through five. The thumb’s is No. 1 and the pinkie’s is No. 5.
Each finger has a series of three bones:
- Proximal phalanx: The longest of the three, this bone extends from the edge of the palm. It is where your rings rest.
- Intermediate phalanx: This bone is part of both finger joints.
- Distal phalanges: The smallest of the finger bones, this is what is commonly called the fingertip.
Bones are connected via fibrous ligaments. The wrist contains a web of ligaments, but the bones in the palm are strung together to keep them from stretching too far apart. Each finger joint is wrapped in ligaments.
Because it has many bones, the hand also contains a lot of cartilage, connective tissue that pads bones as they come together at joints. This cartilage can be damaged by excessive use or injury. Cartilage damage can cause pain in joints.
Bone fractures are among the most common, short-term injuries of the hand. These typically occur during high-impact collisions such as automobile accidents, falls, and sport injuries.