Which triceps head is biggest?

The long head. It runs from the shoulder blade down the inner back of the arm and accounts for the largest share of triceps mass. It is also the head that pushdowns train least, which is why overhead extensions matter.

Do triceps or biceps make your arms bigger?

The triceps. It makes up roughly two thirds of upper-arm mass, compared with about one third for the biceps and brachialis. If arm size is your goal, triceps volume is the higher-leverage place to add work.

Why do overhead extensions work the long head better?

The long head is the only head that crosses the shoulder joint. Raising the arm overhead lengthens it, and a muscle trained in a stretched position produces more growth stimulus. With the arm at your side during a pushdown, the long head is already shortened and contributes far less.

How often should I train triceps?

Twice a week works well for most people. Spread 10–18 hard sets across those sessions, and remember that every bench press, overhead press and dip is adding to that total.

Arms

Triceps

Triceps brachii

Also called: tris, triceps brachii, back of arm

The triceps brachii is the three-headed muscle on the back of the upper arm, and it makes up roughly two thirds of the arm's mass. All three heads extend the elbow, but only the long head crosses the shoulder — which is why overhead extensions train it in a way pushdowns cannot.

front

back

The triceps highlighted on the front and back of the body.

Triceps anatomy

The triceps runs down the back of the upper arm and converges into a single tendon at the elbow. Its three heads all extend the elbow, but they originate in different places, and one of them behaves differently as a result.

The long head is the only head that attaches to the shoulder blade rather than the arm bone, so it crosses the shoulder joint. That means its length — and therefore how much force it can produce — changes with shoulder position. When the arm is overhead, the long head is stretched and trained far more effectively.

The lateral head gives the outer arm its horseshoe shape and responds well to heavier pressing and pushdowns. The medial head sits deepest and works across all elbow extension, particularly in the last part of the range.

Part	What it does
Long head	Crosses the shoulder. Only fully trained with the arm overhead or behind the body.
Lateral head	The outer horseshoe. Biased by pushdowns and heavy close-grip pressing.
Medial head	Deepest head, active throughout elbow extension and especially at lockout.

Origin: Long head: the infraglenoid tubercle of the scapula. Lateral head: the posterior humerus above the radial groove. Medial head: the posterior humerus below the radial groove.
Insertion: The olecranon process of the ulna.

What the triceps does

Elbow extension — straightening the arm. This is the primary job of all three heads.
Shoulder extension, via the long head — pulling the upper arm backward.
Shoulder adduction, via the long head — bringing the arm toward the torso.
Stabilising the elbow during any pressing movement.

Best triceps exercises

Exercise	Equipment	Role	Level	Why
Close-grip bench press	Barbell	primary	Intermediate	The heaviest triceps movement. Loads all three heads with far more weight than any isolation can.
Overhead cable extension	Cable machine	primary	Beginner	Arm overhead puts the long head in a stretched position — the single best long-head exercise.
Skull crusher	EZ bar	primary	Intermediate	Trains the long head with the arm partly flexed. Lower behind the head rather than to the forehead for more stretch.
Rope pushdown	Cable machine	primary	Beginner	Biases the lateral head. Spreading the rope at the bottom adds a hard peak contraction.
Weighted dip (upright)	Dip bars	primary	Advanced	Staying upright keeps the emphasis on the triceps rather than the chest.
Single-arm overhead extension	Dumbbell	primary	Beginner	Fixes side-to-side differences and allows a deeper stretch than a two-handed version.
Diamond push-up	Bodyweight	secondary	Beginner	A no-equipment option that shifts push-up load onto the triceps.

How to train the triceps

Sets per week

10–18 hard sets

Rep range

6–12 for presses, 10–20 for extensions and pushdowns

Frequency

2 sessions per week

Include at least one overhead movement. Pushdowns alone leave the long head — the largest of the three heads — undertrained.
All your pressing already trains the triceps. Count bench and overhead press volume before adding a long list of isolations.
The triceps is roughly two thirds of upper-arm mass, so if arm size is the goal it deserves more attention than the biceps, not less.

Stretches and mobility

Overhead triceps stretch

Reach one hand down your back, pull the elbow gently with the other hand. 30 seconds each side.

Behind-the-back towel stretch

Hold a towel with one hand overhead and one behind the back, gently pull downward.

Common mistakes

Only doing pushdowns

Pushdowns keep the arm at the side, where the long head is shortened and cannot contribute much. Since the long head is the biggest of the three, missing it means missing most of the muscle.

Flaring the elbows on skull crushers

Letting the elbows drift outward turns the movement into a partial press and loads the elbow joint awkwardly. Keep the upper arms roughly vertical and fixed.

Assuming close-grip means hands touching

An extremely narrow grip strains the wrists without adding triceps involvement. Roughly shoulder-width, or slightly narrower, is the useful position.

Triceps FAQ

Which triceps head is biggest?: The long head. It runs from the shoulder blade down the inner back of the arm and accounts for the largest share of triceps mass. It is also the head that pushdowns train least, which is why overhead extensions matter.
Do triceps or biceps make your arms bigger?: The triceps. It makes up roughly two thirds of upper-arm mass, compared with about one third for the biceps and brachialis. If arm size is your goal, triceps volume is the higher-leverage place to add work.
Why do overhead extensions work the long head better?: The long head is the only head that crosses the shoulder joint. Raising the arm overhead lengthens it, and a muscle trained in a stretched position produces more growth stimulus. With the arm at your side during a pushdown, the long head is already shortened and contributes far less.
How often should I train triceps?: Twice a week works well for most people. Spread 10–18 hard sets across those sessions, and remember that every bench press, overhead press and dip is adding to that total.

References

This page is general educational information about exercise and anatomy. It is not medical advice and not a substitute for assessment by a qualified clinician. If you have pain, an injury or a health condition, speak to a professional before changing how you train.