Elbow muscles are commonly referred to as flexors or extensors, depending on how they affect elbow movement. Extensors are on the inside of the arm and help extend the arm outward. Flexors are at the back of the elbow and pull it closer to the body by bending the elbow.

The major muscles involved in moving the elbow include:

  • Biceps brachii: The large muscle of the upper arm flexes the arm and powerfully twists the forearm, turning the palm upward.
  • Triceps brachii: This muscle at the back of the upper arm extends the arm and stabilizes the elbow when the hand is used for fine movements.
  • Brachioradialis: A forearm muscle that flexes the arm at the elbow.
  • Anconeus: This muscle helps extend the forearm at the elbow.
  • Brachialis: This muscle helps flex the elbow inward toward the body.
  • Pronator teres: This muscle extends from the head of the humerus over the elbow to the ulna bone to help flex the elbow, and also enables pronation of the forearm.

Several tendons connect the bones and muscles that meet at the elbow. As the elbow creates a fulcrum, these tendons can be worn and torn with repetitive stressful use.

Tendon tears can be partial or complete, in which the muscle becomes completely detached from the bone. Symptoms of a tendon tear include swelling, bruising, pain, and weakness.

Repetitive stress injuries, due to activities such as playing sports or using a keyboard, can cause inflammation and pain. Collectively, these injuries are known as tendonitis. If the tendon on the outside of the elbow joint is affected, it is called “tennis elbow.” If it is the tendon on the inside of the elbow, the condition is known as “golfer’s elbow.”

Also, improper lifting, such as carrying a heavy item with your arms extended, can cause unnecessary strain on the elbow muscles and tendons.