Triceps brachii
Triceps brachii
Pronunciation: TRY-seps BRAY-kee-eye
For beginners
Making up most of the back of your upper arm, the triceps straightens your elbow — the muscle doing the work at the top of a push-up or the lockout of a bench press.
Show the advanced explanation
Because the long head crosses the shoulder as well as the elbow, exercises that position the shoulder in flexion (like an overhead triceps extension) can stretch and load the long head more than exercises done with the arm at the side.
Structure & function
- Location
- The three-headed muscle covering the entire back of the upper arm.
- Origin
- Three heads: long head from the scapula, lateral and medial heads from the back of the humerus.
- Insertion
- Olecranon of the ulna.
- Main action(s)
- Extends the elbow (the prime mover); the long head also assists shoulder extension since it crosses the shoulder joint.
- Joint(s) crossed
- Elbow joint (all three heads); shoulder joint (long head only)
- Movement plane
- sagittal
- Innervation
- Radial nerve (C6–C8)
- In daily movement
- Straightening the arm to push a door open, push up out of a chair, or reach overhead.
- In exercise
- Prime mover of elbow extension in pushdowns, overhead extensions, and dips; also heavily involved in all pressing exercises (bench press, overhead press).
- Commonly confused with
- Its size (roughly two-thirds of upper-arm mass) is often underestimated compared to the more visually iconic biceps.
- Common misconceptions
- 'Triceps kickbacks are the best triceps builder' is an oversimplification — compound pressing movements typically contribute more total triceps work for most lifters.
Exercises that use this muscle
As a primary mover
⚠ Safety note
Sharp elbow or upper-arm pain during heavy pressing or extension work should be assessed rather than pushed through.
Sources
“The triceps brachii extends the elbow, and its long head assists shoulder extension.”
Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.5 Muscles of the Pectoral Girdle and Upper Limbs
Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19
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