Clavicular HeadClavicular Head of Pectoralis Major

chestPars clavicularis musculi pectoralis majoris

The clavicular head is the upper third of the pectoralis major, running from the collarbone to the arm. It is the part that lifts the arm forward and up, which is why incline pressing emphasises it.

Clavicular Head highlighted on an anatomical figure, from the front.
Where it sits, from the front.

This is the strip of pec that runs from the inner half of your collarbone diagonally down to your upper arm. In the gym it is simply "upper chest", and it is the only part of the pectoralis major whose fibres run upward toward the shoulder rather than straight across or downward.

That angle decides what it does. Because the fibres pull from the arm up toward the collarbone, this head is the one that raises the arm forward and above shoulder height. Hold your arm out in front of you at forty-five degrees above horizontal and push toward the ceiling and inward, and the clavicular head is doing most of the work.

It is also the part that gives the chest a defined upper border below the collarbone. Because the fibres run in the opposite direction to the lower fibres of the same muscle, the two parts genuinely oppose each other in the up-and-down plane: what the clavicular head lifts, the abdominal head pulls back down.

Training notes

The upper chest is the most commonly under-developed part of the pecs, and the reason is scheduling rather than anatomy. Flat pressing is what most people do first, most often and heaviest, and it does not line up well with fibres that run upward. An incline of roughly fifteen to thirty degrees does; steeper than about forty-five degrees and the front deltoid starts taking the movement over, which is the failure mode this exercise is trying to avoid.

Low-to-high cable work — a crossover set with the pulleys at the bottom, hands finishing in front of the collarbones — trains the same fibres through the sweep across the body rather than through the press. It is a useful pairing with incline pressing because the two load opposite ends of the same range.

One thing not to do is chase the upper chest with front raises. Those are a deltoid movement that the clavicular head assists; the arm is not travelling across the body, so the pec is never the muscle deciding the outcome.

Anatomy

Origin
  • Anterior surface of the medial half of the clavicle
Insertion
  • Crest of the greater tubercle of the humerus, lying anterior to the other fibres and attaching lowest on the crest
Actions
  • Flexes the arm forward and upward, as in an incline press or a front raise
  • Horizontally adducts the arm across the chest at and above shoulder height
  • Assists adduction and internal rotation of the humerus
Innervation
Lateral pectoral nerve (C5–C6)

Exercises

Antagonists

Synergists