Teres minor

muscle

Where it runs

From the outer edge of the shoulder blade to the back of the top of the upper arm bone, just below the infraspinatus.

Part of the rotator cuff. Turns the arm outwards and steadies the joint.

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

3 × 12–15

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

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.