Bony landmark · Shoulders

Acromion

Acromion

The acromion is the flat shelf of bone at the very tip of the shoulder — the bony point you can feel through the skin, and the outer end of the ridge that crosses the shoulder blade. It meets the collarbone in front at the acromioclavicular joint. The middle fibres of the deltoid take origin from it and the trapezius inserts onto it, so it is the platform the whole cap of the shoulder hangs from. It is also a roof: the supraspinatus tendon and the subacromial bursa pass through the narrow space between it and the head of the arm bone, which is the space that narrows when the arm is lifted overhead.