Infraspinatus. Meaning "below the spine"
Along with the other rotator cuff muscles, the Infraspinatus is responsible for keeping the head of the humerus in it's socket. And because of this extremely important job, the infraspinatus is possibly one of the most frequently afflicted muscles of the body.
Now the crazy thing is that despite being located behind the shoulder on the scapula, the infraspinatus trigger points actually cause pain in the front the shoulder and quite often feels like it's deep in the joint. It may also travel some distance down the arm as far as the forearm and entire thumb-side of the hand as well as up towards the upper back and neck. The pain can be excruciating.
You may also feel weakness and stiffness in the shoulder which can mean that your arm tires easily. You may have problems reaching behind your back (bra?) and sometimes even reaching behind your head (hair?). Lying on the shoulder can be painful but lying on the opposite shoulder can be worse as the weight of the arm pulls on the infraspinatus even more. Stretching also makes things worse.
Often issues with the infraspinatus can be misdiagnosed as biceps tendinopathy, frozen shoulder, impingement or bursitis.
So what causes problems in the infraspinatus?
Strengthening the infraspinatus (and the other rotator cuff muscles) becomes imperative to avoid reoccurrence which is why massage and strengthening go hand in hand.