A person with medial epicondylitis has inflammation of the medial epicondyle. The medial epicondyle is part of the humerus bone, near the elbow.

Tendons attach the muscles of the forearm to the medial epicondyle. Strenuous use of the forearm muscles can cause inflammation of the bone where the tendons attach to the medial epicondyle. Most cases of medial epicondylitis resolve over 4-6 weeks with treatment and rest.