Acromion is a hook-like process present laterally out of the shoulder blade of scapula bone of the shoulder joint.  It acts like a hood over the rotator cuff and gives it protection. The rotator cuff runs underneath surface of acromion.  Occasionally the spurs in acromion or the spurs out of the acromioclavicular joint, a joint formed between acromion and clavicle, may cause injury to the rotator cuff leading to inflammation called tendinitis or tearing of the rotator cuff.