From the Guidelines
The wrist is a complex joint connecting the forearm to the hand, composed of eight carpal bones arranged in two rows, with the proximal row including the scaphoid, lunate, triquetrum, and pisiform bones, and the distal row containing the trapezium, trapezoid, capitate, and hamate bones. The wrist joint is stabilized by numerous ligaments, including the palmar radiocarpal, dorsal radiocarpal, and ulnocarpal ligaments, as well as the triangular fibrocartilage complex (TFCC) which is crucial for stabilizing the ulnar side of the wrist 1. The carpal bones articulate with the radius and ulna proximally and with the metacarpal bones distally.
Key features of the wrist anatomy include:
- The scapholunate diastasis of >4 mm and dorsal tilt of the lunate of >10 suggests dorsal intercalated segmental instability 1
- The lunotriquetral diastasis with scapholunate angle <30 and capitolunate angle of >30 suggests volar intercalated segmental instability 1
- High-frequency US is useful for visualizing wrist tendons as well as intrinsic and extrinsic carpal ligaments, with dynamic “clenched fist” maneuvers improving detection of low-grade injuries 1
- The wrist allows for a wide range of motion, including flexion, extension, radial deviation, ulnar deviation, and circumduction, which are essential for hand function.
Blood supply to the wrist comes primarily from the radial and ulnar arteries, while innervation is provided by the median, ulnar, and radial nerves 1. The median nerve passes through the carpal tunnel along with nine flexor tendons, making it susceptible to compression in carpal tunnel syndrome. Understanding wrist anatomy is critical for diagnosing and treating common conditions such as carpal tunnel syndrome, De Quervain's tenosynovitis, and scaphoid fractures.
From the Research
Anatomy of the Wrist
The wrist is a complex joint that consists of multiple bones, ligaments, and tendons. The anatomy of the wrist includes:
- Eight small bones (carpals) that form the wrist joint
- Five metacarpal bones that connect the wrist to the fingers
- Multiple ligaments that connect the bones and provide stability to the joint, including the scapholunate (SL) and lunotriquetral (LT) ligaments 2
- Tendons that connect the muscles of the forearm to the bones of the wrist and fingers
Associated Injuries and Treatment
Injuries to the wrist can include fractures, ligament sprains, and tendon lesions. The treatment of these injuries can vary depending on the severity and location of the injury. For example:
- Fractures of the distal radius are frequently associated with injuries of the SL and LT ligaments, and may require immobilization of the wrist 2
- Flexor tendon lesions of the hand may be treated with splints, with or without wrist immobilization, although the evidence base for these techniques is limited 3
- Wrist sprains may be treated with early mobilization, as cast immobilization has been shown to have no benefit in some cases 4
Ligaments of the Wrist
The ligaments of the wrist play a crucial role in providing stability to the joint. The SL and LT ligaments are particularly important, as injuries to these ligaments can be difficult to diagnose and treat. For example: