lateral epicondyle of the humerus
The extensor carpi radialis brevis muscle originates from the common extensor tendon off the lateral epicondyle of the humerus. So, an injury to this tendon would result in pain near the lateral epicondyle. Tennis elbow is due to the repetitive use of superficial extensor muscles of the forearm--the pain is often felt at the lateral epicondyle and it radiates down the posterior surface of the forearm. None of the other bony landmarks are associated with the common extensor tendon, although the medial epicondyle is the origin of the common flexor tendon.