DO YOU SUFFER WITH ELBOW OR WRIST PAIN?
Basic functional anatomy of the wrist, hand and elbow
Wrist and hand
This joint complex involves the distal end of the radius, the ulna and the 8 carpal bones of the wrist.
The wrist is formed where the two bones of the forearm – the radius (the larger bone on the thumb side of the arm) and the ulna (the smaller bone on the little finger side) meet the carpus. The wrist is made up of multiple joints where the bones of the arm and hand meet to allow movement.
There are 2 rows of 4 carpal bones within the wrist: the proximal row comprises the scaphoid, lunate, triquetral and pisiform; the distal row the hamate, capitate, trapezoid and trapezium.
There are 2 functional joint complexes the inferior radio-ulnar joint that allows pronation and supination, and the radoiocarpal joint where flexion and extension occurs. Within the wrist and part of the radoiocarpal complex, there are 2 distinct rows of joints: between the radius and proximal row of carpal bones, and between the proximal and distal row of carpal bones.
Ligaments & tendons of the hand and wrist
The ligaments are tough bands of connective tissue that connect the bones to support them and keep them in place. Important ligaments of the hand are:
- collateral ligaments. Strong ligaments on either side of the finger and thumb joints which prevent sideways movement of the joint.
- volar plate. A ligament that connects the proximal phalanx to the middle phalanx on the palm side of the joint. As the joint in the finger is straightened, this ligament tightens to keep the PIP joint from bending backward.
- Radial and ulnar collateral ligaments. A pair of ligaments which bind the bones of the wrist and provide stability.
- Yolar radiocarpal ligaments. A complex web of ligaments that support the palm side of the wrist
- Dorsal radiocarpal ligaments. Ligaments that support the back of the wrist.
- Ulnocarpal and radioulnar ligaments. Two sets of ligaments that provide the main support for the wrist.
Rings of connective tissue, called pulleys hold tendons of the fingers close to the bone.
The main tendons of the hand are:
- Superficialis tendons, which pass through the palm side of the wrist and hand, and attach at the bases of the middle phalanges. They act with the profundus tendons to flex the wrist and MCP and PIP joints.
- Profundus tendons, which pass through the palm side of the wrist and hand, and attach at the bases of the distal phalanges. They act with the superficialis tendons to flex the wrist and MCP and PIP joints. They also flex the DP joints.
- Extensor tendons of the fingers, which attach to the middle and distal phalanges and extend the wrist, MCP, PIP and DP joints.
- Flexor tendons, nine long tendons which pass from the forearm through the carpal tunnel of the wrist. They diverge in the palm, where two go to each finger (one attaches at the DP and one at the MCP) and one goes to the thumb.
- Extensor pollicis brevis and abductor pollicis longus, which run from the muscles in the top of the forearm and enable movement of the thumb.
Several muscles surround the elbow, allowing for arm movement. The two main muscles responsible for bending and straightening the arm at the elbow are: the triceps at the back of the arm and biceps at the front.
Tough bands of connective tissue called ligaments hold the bones of the elbow together. The two main ligaments connecting the humerus and ulna are: ulnar-collateral ligament, also called the medial collateral ligament, which runs along the inside of the elbow and the lateral collateral ligament, also called the radial collateral ligament, which runs along the outside of the elbow.
The ligaments form a capsule around the joint lined with a smooth membrane, synovium. The synovium produces a viscous liquid, called synovial fluid, which lubricates the joint.
The primary tendons are: biceps tendon, which attaches the biceps on the front of the arm to the radius, enabling the bend to occur, and triceps tendon, which attaches the triceps to the ulna, enabling the elbow to straighten.