S9) The Wrist Flashcards
What is the wrist joint?
The wrist joint (aka radiocarpal joint) is a synovial joint in the upper limb, marking the area of transition between the forearm and the hand
What are the structures forming the wrist joint?
- Distally – proximal row of the carpal bones (except the pisiform)
- Proximally – distal end of the radius and the articular disk
Does the ulna form part of the radiocarpal joint?
No, it articulates with the radius at the distal radioulnar joint but is prevented from articulating with the carpal bones by the articular disk
Describe the blood supply to the wrist joint
Arterial supply via branches of the dorsal and palmar carpal arches, which are derived from the ulnar and radial arteries
Describe the innervation of the wrist joint
- Median nerve – anterior interosseous branch
- Radial nerve – posterior interosseous branch
- Ulnar nerve – deep and dorsal branches
Identify the 4 ligaments which ensure the stability of the wrist joint
Describe the location and function of the palmar radiocarpal ligament
- Location: anterior side of the hand, passes from the radius to both rows of carpal bones
- Function: increases stability, ensures the hand follows the forearm during supination
Describe the location and function of the dorsal radiocarpal ligament
- Location: posterior side of the hand, passes from the radius to both rows of carpal bones
- Function: increases stability of the wrist, ensures that the hand follows the forearm during pronation
Describe the location and function of the ulnar collateral ligament
- Location: runs from the ulnar styloid process to the triquetrum and pisiform
- Function: prevents excessive medial joint displacement (in union with other collateral ligament)
Describe the location and function of the radial collateral ligament
- Location: runs from the radial styloid process to the scaphoid and trapezium
- Function: prevents excessive lateral joint displacement (in union with other collateral ligament)
What type of joint is the wrist joint?
The wrist is an ellipsoid type synovial joint, allowing for movement along two axes
Identify the four different types of movement possible at the radiocarpal joint as well as the individual muscles involved
- Flexion – flexor carpi ulnaris and flexor carpi radialis (assistance from the flexor digitorum superficialis)
- Extension – extensor carpi radialis longus and brevis and extensor carpi ulnaris (assistance from the extensor digitorum)
- Adduction – extensor carpi ulnaris and flexor carpi ulnaris
- Abduction – abductor pollicis longus, flexor carpi radialis, extensor carpi radialis longus and brevis
What is the carpal tunnel?
The carpal tunnel is a narrow passageway on the anterior portion of the wrist, serving as the entrance to the palm for several tendons and the median nerve
Describe the borders of the carpal tunnel
- The deep carpal arch (formed by carpal bones) forms a concave surface acting as the floor
- The overlying superficial flexor retinaculum acts as the roof
Identify the carpal bones forming the carpal arch laterally and medially
- Lateral: scaphoid and trapezium tubercles
- Medial: hook of hamate and pisiform