Also known as “Swimmer’s Shoulder” or “Thrower’s Shoulder”, occurs when the tendons of the rotator cuff muscles become irritated and inflamed as they pass through the subacromial space. The acromion is a part of the shoulder blade that meets with the clavicle (collar bone).  Together they form an arch, and some of the rotator cuff tendons pass beneath this arch.  As you raise your arm, the space under the arch may get tighter which pinches those tendons.  If this continues, it may result in pain, weakness and loss of movement at the shoulder.