In rare cases, the long head can originate from the lateral margin of the scapula and from the capsule of the shoulder joint.

It has been suggested that the long head fascicle is employed when sustained force generation is demanded, or when there is a need for a synergistic control of the shoulder and elbow or both.

[3] With its origin on the scapula, the long head also acts on the shoulder joint and is also involved in retroversion and adduction of the arm.

[2] The triceps can be worked through either isolation or compound elbow extension movements and can contract statically to keep the arm straightened against resistance.

Static contraction movements include pullovers, straight-arm pulldowns, and bent-over lateral raises, which are also used to build the deltoids and latissimus dorsi.

In the horse, 84%, 15%, and 3% of the total triceps muscle weight correspond to the long, lateral, and medial heads, respectively.