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Triceps brachii
The muscle that straightens the elbow, and the one doing most of the work in every push-up and press.
Latin name: Musculus triceps brachii. In plain English, the three-headed muscle at the back of the upper arm. It is filed here under arm and forearm.
Reference information, not a diagnosis. Where a symptom is described below, it is there so you can describe your own more precisely to a clinician — not so you can name what you have.
Where it is
The triceps fills the whole back of the upper arm. Two of its heads, lateral and medial, come from the shaft of the humerus itself, above and below the spiral groove where the radial nerve winds around the bone. The third, the long head, comes from the shoulder blade just below the socket, which is why it crosses two joints while the others cross one. All three merge into a broad tendon on the point of the elbow.
That spiral groove matters clinically. The radial nerve lies against bare bone as it crosses behind the humerus, so a mid-shaft fracture of the upper arm — or prolonged pressure, as when someone falls asleep with the arm over a chair back — can leave a wrist that cannot be lifted, the classic wrist drop.
| Feature | Detail |
|---|---|
| Origin | Long head from the infraglenoid tubercle of the scapula; lateral head from the humerus above the radial groove; medial head from the humerus below the groove |
| Insertion | Olecranon of the ulna, the point of the elbow |
| Nerve | Radial nerve (C6-C8) |
| Main actions | Extension of the elbow; the long head also extends and adducts the shoulder |
What it does
Straightening the elbow against resistance is almost entirely triceps. Every press, push-up, dip and overhead press finishes with it, and in the bench press and the overhead press it is often the part that fails first. The medial head does the day-to-day work at low loads; the lateral and long heads contribute more as the effort rises.
The long head's shoulder attachment gives it a second role: pulling the arm backward and inward, and holding the head of the humerus down in the socket when the arm is loaded overhead. It is also the head that gets stretched when you reach an arm behind your head, which is why overhead triceps work feels so different from work with the arm at your side.
Exercises that load it
| Exercise | Category | Muscles the exercise library lists |
|---|---|---|
| Dips | Strength | Triceps, chest, front shoulder |
| Push-ups | Strength | Chest, triceps, front shoulder, core |
| Bench press | Strength | Chest, triceps, front shoulder |
| Overhead press | Strength | Shoulders, triceps, core |
Dips and close-grip pressing are the heaviest triceps loading you can do with compound movements, because the elbow travels through a long range under significant load. Overhead positions bias the long head, since it is lengthened at the shoulder before the elbow even starts to extend. Push-ups load it well at bodyweight; narrowing the hands increases the share the triceps takes from the chest.
How it is lengthened
Reach one arm overhead, bend the elbow so the hand drops behind the head, and use the other hand to guide the elbow gently backward. That lengthens the long head at both joints at once. If the shoulder rather than the arm is what feels tight, ease off — this position also loads the shoulder capsule and is not a good place to force anything.
When it goes wrong
| Problem | What it typically feels like | Usual setting |
|---|---|---|
| Triceps tendinopathy | An ache right at the point of the elbow, worse on hard pressing or locking out under load | A rapid increase in pressing volume, or a lot of repeated locking out with heavy weight |
| Radial nerve compression at the spiral groove | Wrist drop with weakness extending the wrist and fingers, and numbness on the back of the hand | A humeral shaft fracture, or sustained pressure on the upper arm during deep sleep |
| Olecranon bursitis | A soft swelling like a small balloon over the point of the elbow, often not very painful | Leaning on the elbow repeatedly, or a direct knock |
A wrist and fingers that cannot be lifted against gravity after an injury to the upper arm is a nerve emergency in the sense that it needs assessment quickly. So does a hot, red, rapidly swelling elbow, which can mean infection.
Nothing on this page is a treatment plan. If a problem is limiting what you do, is not improving, or is getting worse, the right next step is an assessment by a doctor or a physiotherapist who can examine you.
Sources: descriptive anatomy from Gray's Anatomy of the Human Body, 20th US edition (1918), which is in the public domain; Latin names follow Terminologia Anatomica, published by the Federative International Programme for Anatomical Terminology. Nerve root levels are the conventional ranges taught from those sources and vary between individuals and between textbooks. Exercise cross-links use the TempoLife exercise library. Checked 2026-09-06.
Frequently asked questions
Why is the triceps bigger than the biceps?
Because it has three heads and a larger total cross-section, and because straightening the arm against gravity — pushing, pressing, getting up off the floor — is a bigger everyday job than bending it. Most of the visible mass of the upper arm is triceps.
Do I need isolation work for the triceps?
Not necessarily. Dips, close-grip pressing and overhead pressing load it heavily. Isolation work adds volume for a specific head, most usefully the long head through an overhead position, but the compound movements do the bulk of the work.
What is the difference between tennis elbow and triceps pain?
Tennis elbow is felt on the outer bony bump of the elbow and comes from the wrist extensor tendons; triceps tendon pain is felt right at the point of the elbow, at the back. Location separates them reasonably well.
Nearby in this reference
Biceps brachii
The two-headed muscle at the front of the upper arm
Forearm and grip
The muscles below the elbow that close your hand
Deltoid
The cap of the shoulder
Rotator cuff
The four small muscles that hold the shoulder in its socket
Trapezius
The big diamond across the upper back and neck
Rhomboids
The straps that pull the shoulder blades together
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