Muscle Monday 5: Rotator Cuff pt. 2: Infraspinatus

Part two of our rotator cuff series is the infraspinatus. It is responsible for external rotation (also called lateral rotation - see second image), adducting the shoulder (bringing your arm towards the midline of your body), and stabilizing the head of the humerus in the glenoid fossa. It is located below the supraspinatus, below the spine of the scapula and covers the entire lower surface of the scapula. It is close to the surface of the skin so it is possible to directly palpate it.

Direct injuries to this muscle are somewhat rare. Most concerns will likely come from postural issues. Infraspinatus tends to get elongated and weak from the shoulders being in a slouched and rounded-forward position. In this case, stretching would be contraindicated and you would instead want to focus on strengthening the muscle and learning how to activate it.

If you’ve done face pulls or reverse flyes in the gym, you’ve already worked on this muscle, even indirectly. Face pulls are an excellent shoulder exercise for shoulder injury prevention in general so if you’re not already doing them, I highly recommend adding them into your routine. In more severe cases, you may need a more isolated exercise - here is a video demoinstrating a very simple and effective exercise that targets infraspinatus.

This muscle has a bit of a functional twin, the teres minor which I’ll be covering next week.