How many muscles are in your triceps?

There are three muscles that comprise the triceps: the long head, the medial head and the lateral head. The names of these muscles are based on their origin attachment points.

The long head muscle of the triceps originates from the part of the scapula known as the glenoid cavity and branches out into two halves, giving the muscle its horseshoe shape.

The medial head of the triceps originates from the upper and interior side of the humerus, the bone of the upper arm that forms joints between the shoulder and elbow.

The lateral head of the triceps originates from the upper half of the outside surface of the humerus and connects to the septum.