Deltoid

muscle

Where it runs

The cap of the shoulder: from the collarbone, the top of the shoulder and the ridge of the shoulder blade down to the outside of the upper arm.

Raises the arm to the front, the side and the back.

The back part helps hold the arm as it comes down behind the line of the body.

Hold a light band at shoulder height with straight arms and pull it apart to your chest.

3 × 12–15

Elbow tucked at your side, turn the forearm out against a light band.

3 × 12–15

Phase 1 — Set the shoulder blades — Shoulder: kipping works, strict pull-ups do not
Phase 2 — Own the top and the way down — Shoulder: kipping works, strict pull-ups do not

Other structures the same drills work.

General anatomy, simplified. It describes a structure, not anybody's shoulder, and cannot say what is wrong with yours.