The eight carpal bones are the small bones of the wrist that connect the hand to the forearm. They are arranged in two rows. The reference states: "The eight carpal bones (scaphoid, lunate, triquetrum, pisiform, hamate, capitate, trapezoid, and trapezium) are arranged in two rows between the metacarpal bases distally and the distal radius and ulna."
Here's a breakdown of the carpal bones in table format:
Row | Bones |
---|---|
Proximal | Scaphoid, Lunate, Triquetrum, Pisiform |
Distal | Trapezium, Trapezoid, Capitate, Hamate |
The Carpal Bones
Here's more detail about each bone:
- Proximal Row:
- Scaphoid: This is the largest bone in the proximal row and is often fractured during falls.
- Lunate: Located next to the scaphoid, this bone is crescent-shaped.
- Triquetrum: This is a pyramid-shaped bone located on the medial side of the wrist.
- Pisiform: A small, pea-shaped bone that sits on top of the triquetrum.
- Distal Row:
- Trapezium: Located on the thumb side of the wrist.
- Trapezoid: Adjacent to the trapezium.
- Capitate: The largest bone in the distal row, found in the center of the wrist.
- Hamate: Characterized by a hook-like process on its palmar surface.
Arrangement and Function
The carpal bones work together to provide wrist flexibility and stability. The two rows of carpal bones move in relation to each other and to the bones of the forearm and hand to enable a wide range of motion. They are connected by ligaments and work in coordination with tendons and muscles, allowing for precise movements and strong grips. The TFCC (triangular fibrocartilage complex) separates the ulna from the carpal bones, contributing to wrist stability and cushioning.