When I received my MRI back from the doctor’s office it just said “rotator cuff tear”. What a tease!
There are four rotator cuff muscles in the shoulder and each of them does a different, vitally important role. Even medical professionals tend to lump them together into one poorly-defined category. But the better you know each one and can strengthen them with precision, the easier it will be to keep your shoulders happy and healthy.
The rotator cuff muscles are responsible for the rotational qualities of your arm bone in your shoulder socket. They are also vital to the stabilization of the arm bone since the shoulder socket is very shallow and the bone has the potential to slip out of place without muscular support. This means that the balance of each individual muscle is necessary to keep the arm bone centered in the joint.
So let’s meet the team!
The subscapularis is responsible for internal rotation and stabilizes the arm bone from slipping forward in the shoulder joint. This is a very important job since the most common shoulder dislocation is in a forward direction. The subscap attaches to the front of the arm bone and runs along the underneath side of the shoulder blade to attach along its inside edge. This means it’s very difficult to poke at your subscapularis since it’s mostly an internal muscle.
The supraspinatus is responsible for rotating the arm bone up in the socket and protects against the arm popping sideways out of the socket. It attaches to a boney ridge on the top of the shoulder blade and runs through a little hole in between the shoulder socket and the arm bone to fasten to the outside of the arm bone. This journey through the little hole between two bones makes the supraspinatus especially prone to sadness because improper shoulder mechanics can crush the tendon and over time lead to tearing. Since it’s right underneath the powerful deltoid it is easy to miss if you aren’t paying attention.
The infraspinatus is responsible for external rotation and stabilizes the arm bone from slipping backwards out of the shoulder socket. It attaches to the outside edge of the shoulder blade and runs along the top of the shoulder blade to fasten to the back of the arm bone. Since modern posture biases internal rotation of the shoulder, most of us could use a little more external rotation love from the infraspinatus.
The teres minor is the bff of the infraspinatus and they do everything together. The teres minor is a smaller muscle that sits just under the infraspinatus and reinforces the external rotation and stabilization role. For our purposes you can think of the teres minor as the Robin to the infraspinatus’ Batman.
Compared to the big, beefy deltoids, biceps, and triceps, the rotator cuff muscles are relatively small. If you only do shoulder strengthening with heavier weights it is very easy to go right to the bigger muscles since they are designed for the big, dramatic movements. To feel and strengthen the rotator cuff muscles it is better to use light weight, or even no weight at all, to make sure that the bigger muscles aren’t called into action.
The video below shows three unweighted, easy isometrics that you can use to experience each of your rotator cuff muscles and develop your relationship with them. Once that relationship is established you can add weight and movement to build their capacity. But you can’t strengthen a muscle that you can’t find or feel so this is a great start in getting to know your shoulders so you can all be friends!
Spend time getting to know your rotator cuff team. It’s a relationship you will value for the rest of your life.