Lateral epicondylitis involves tendinopathy at the origin of which muscle group?

• A. Extensor Carpi Radialis Brevis
• B. Flexor Carpi Ulnaris
• C. Biceps Brachii
• D. Rectus Femoris

Answer: (A)

Lateral epicondylitis is a tendinopathy at the origin of the wrist extensor muscles, most commonly the extensor carpi radialis brevis. This muscle’s tendon anchors to the lateral epicondyle of the humerus via the common extensor tendon, and repetitive overuse causes degenerative changes and microtears there. That’s why pain is felt at the lateral elbow, especially with activities that extend the wrist or grip firmly.

The other muscles listed don’t fit because they’re either not wrist extensors attaching at the lateral epicondyle (for example, flexor carpi ulnaris originates from the medial epicondyle and serves the opposite, flexion/ulnar deviation) or they are unrelated to the elbow region (biceps brachii spans the shoulder to the forearm, and rectus femoris is a thigh muscle).