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Pain Profile: Shoulder Impingement Syndrome

The shoulder is an incredibly mobile joint but is also quite prone to injuries. One of the many ailments of the shoulder includes shoulder impingement syndrome (SIS). Some nicknames for SIS include the painful arc or swimmer’s shoulder (Anderson and Parr, 2009, p. 415). People who suffer from SIS usually have participate in lots of overhead and pressing movements, have over developed upper trapezius muscles compared to the middle and lower trapezius muscles, weakness and tightness of infraspinatus and teres minor, and have weaknesses throughout the scapular stabilizers and postural muscles.


SIS involves several different structures within the shoulder including the rotator cuff, acromion, subacromial bursae, and coracoacromial ligament. The aforementioned structures are defined as:

  • Rotator cuff – a group of four muscles that include the supraspinatus, infraspinatus, teres minor, and subscapularis. All of these muscles attach from the scapula (shoulder blade) to the humerus (upper arm). The rotator cuff is the main stabilizer of the shoulder to keep the shoulder in place in the socket.

  • Acromion – a specific point on the scapula. The acromion wraps around the shoulder and attaches onto the clavicle (collar bone). The acromion is near the superior (top) portion of the deltoid.

  • Subacromial bursa – a bursa is a fluid filled sac that helps reduce friction between tendons and bones, tendons and skin, and ligaments and bones (Anderson and Parr, 2009, p. 136). The subacromial bursa is underneath the deltoid and the acromion.

  • Coracoacromial ligament – a ligament attaches one bony point to another bony point. The coracoacromial ligament attaches from the coracoid process on the scapula to the acromion.

During SIS, the supraspinatus muscle and the subacromial bursa of the rotator cuff gets compressed between the acromion and the coracoacromial ligament which causes pain and inflammation in the shoulder. Tears throughout the supraspinatus may occur. If the condition has been ongoing for many months or years the su