Triceps brachii muscle is often simply called the triceps (both singular and plural). However, the term triceps (Latin for "three-headed") can mean any skeletal muscle having three origins, such as the triceps surae.

The three heads have the following names and origins:

• The "Long head": infraglenoid tubercle of the scapula
• The "Lateral head": posterior shaft of the humerus, lateral and superior to the radial (spiral) groove.
• The "Medial head": posterior shaft of the humerus, medial and inferior to the radial (spiral) groove.

The fibers converge to a single tendon to insert onto the olecranon process of the ulna (though some research indicates that there may be more than one tendon.)

Many mammals have a fourth head, the "Accessory head", which is between the Lateral and Medial heads.