Anatomy of the wrist
The term “wrist” is the collective term for 2 separate joints. These are the proximal wrist (i.e. near the middle of the body) and the distal wrist. The proximal wrist is also called “Articulatio radiocarpalis” and is composed of the bone of the forearm, the so-called radius (lat.
Radius), and the proximal carpal bone (lat. Os carpalis). It is an ellipsoid/egg joint due to its 2 degrees of freedom and its shape.
A special feature of the proximal wrist is the presence of a small interarticular disc (Discus articularis). The disc is actually a joint between ulna and radius, but is involved in the “Articulatio radiocarpalis” due to its position. The distal wrist – or “Articulatio mediocarpalis” – describes the articulated connection between the row of proximal and distal carpal bones.
These include the following bones: In contrast to the proximal wrist, the distal wrist is less mobile due to ligaments and muscles and is functionally a hinge joint. Apart from the carpal bones and the radius, the ulna is also often affected by fractures of the wrist.
- Scaphoid (Os scpahoideum)
- Moon leg (Os lunatum)
- Triangular leg (Os triquetrum)
- Large polygonal bone (Os trapezium)
- Small polygon bone (Os trapezoideum)
- Capitate bone (Os capitatum)
- Hooked leg (Os hamatum)
Traumatic wrist fractures are the most common.
The fracture varies according to the mechanism of the accident. In a fall on the hand, the radius is typically affected. Depending on the position of the hand at the time of the application of force during a fall, fractures can be differentiated into bending and stretching positions.
In extension position (i.e. when the hand is stretched), the so-called Colles fracture of the radius occurs. A Smith fracture results from a fall on the bent hand. This is less common, since a fall results in a reflex-like supporting movement, i.e. an extension position, of the hand.
Children and elderly people are frequently affected. The latter group is exposed to an increased risk of falling due to age-related immobility. In addition, old bones are more unstable and fragile than young, healthy bones due to osteoporosis. Wrist fractures can also occur during sports or direct exposure to violence. A fracture of a carpal bone, the scaphoid bone, is also typical.
