Which tendon is primarily affected in lateral epicondylitis?

Lateral epicondylitis, commonly known as tennis elbow, primarily involves the extensor carpi radialis brevis tendon. This condition is characterized by pain and tenderness on the lateral side of the elbow, which results from repetitive overuse of the forearm muscles that originate at the lateral epicondyle of the humerus.

The extensor carpi radialis brevis is significant because it plays a crucial role in wrist extension and stabilizing the wrist during activities that involve gripping and lifting. The repetitive strain on this tendon leads to microtears, inflammation, and subsequent pain, making it the tendon chiefly implicated in lateral epicondylitis.

Understanding the anatomy and biomechanics of the forearm can help clarify why this specific tendon is affected. The other tendons listed, while they also originate near the lateral epicondyle, do not exhibit the same degree of involvement in this particular condition.