The triceps brachii is a muscle with three heads, hence its name. These heads are the long head, lateral head, and medial head. Due to the overwhelming majority of the triceps brachii, they are traditionally considered a powerhouse. This expression refers to muscle fibers that quickly deplete energy, and the triceps are particularly dominant in this characteristic. Triceps are involved in any pushing motion.

Long Head

The long head of the triceps originates from the scapula and inserts into the ulna. The long head can extend the elbow and also helps in shoulder extension (pulling the upper arm backward). Since the long head of the triceps acts on the shoulder joint, it is preferentially recruited over the other parts of the triceps when the shoulder is flexed (arm above the head).

Lateral Head

The lateral head of the triceps originates from the humerus and inserts into the ulna, forming the exterior of the triceps. Apart from the long head, the lateral head also provides the horseshoe appearance of the triceps. The lateral head has one function, which is the extension of the elbow.

Medial Head

Like the lateral head, the medial head originates from the humerus and inserts into the ulna. However, the medial head is almost invisible to the naked eye. Most of the muscle lies underneath the lateral and long heads. Only the bottom part of the medial head (near the elbow) is visible. Similar to the lateral head, the medial head is responsible for elbow extension.