Rotator Cuff Injuries – Causes, Exercises and more

rotator cuff injury

Rotator Cup, Rotor Cuff, Rotary Cuff – we’ve heard it called many things – but just what is your Rotator Cuff?

Many people with shoulder pain present to a physiotherapist, or doctor, and get diagnosed with a rotator cuff injury. These people can be left confused, because they don’t fully understand what exactly that is, or why it matters. All they know, is their shoulder hurts, and they want it to stop. 

The first step to rehab is understanding your injury, and understanding why or how you hurt. 

What is a Rotator Cuff?

Is it a muscle? A ligament? A tendon? A bone? 

The rotator cuff is a couple of those things. It is a collection of muscles. Four muscles to be exact. Muscles turn into tendons, and tendons attach muscles to bones. Therefore, muscles allow us to move our bones. 

The short answer: the rotator cuff is 4 muscles and their associated tendons. 

Here’s a picture:

rotator cuff muscles

In the picture, the red parts are the muscle bellies, the white parts are the tendons. These 4 muscles start on your shoulder blade (scapula) and attach to your upper arm (humerus). The left part of the picture shows what it would look like from the front (looking through and past your torso/rib cage). On this side of the shoulder blade, we have 1 of the 4 rotator cuff muscles: the subscapularis muscle. The right part of the picture shows what it would look like from the back, with the supraspinatus muscle on the top, and two muscles, the infraspinatus and teres minor, coming from the big body of the shoulder blade. 

Individually (and simplified), these muscles do the following movements:

  • Supraspinatus: arm abduction (lifting your arm up to the side)
  • Infraspinatus and Teres Minor: external rotation (turning your arm outwards)
  • Subscapularis: internal rotation (turning your arm inwards) 

However, like most things in our body, it’s not that simple. The rotator cuffs’ main job is to keep the humeral head (ball on the end of your upper arm), centred in the glenoid cavity (the shoulder socket) (see below).

rotator cuff bones

As you can see, the glenoid cavity (shoulder socket) is pretty shallow, so the rotator cuff works quite hard in certain positions – for example, when working overhead or when reaching. (The cavity is this shallow to allow our shoulders to be super mobile – and don’t worry, there are other things that help – but that’s a different blog post!). 

How do you hurt your rotator cuff?

You can injure your rotator cuff in many ways, but here are some of the more common ways:

  • Repetitive use (using your shoulder a lot tires out the rotator cuff and it gets painful)
  • Overreaching (or lots of reaching)
  • Overhead work (working with your arms above your head, especially for a long time) 
  • Trauma or falling (like a body-check in hockey, or falling on your arm)
  • Combining these things – like repetitive overhead reaching, can be very strenuous on your rotator cuff


A Word on Injury ‘Names’

When you injure a muscle, it’s called a strain (you sprain a ligament). So therefore, a muscle injury to 1 (or more) of your 4 rotator cuff muscles is called a rotator cuff strain. If a strain worsens, or it is a big strain, it can become a partial tear, and progress further to a full tear. A complete tear is when the muscle detaches from the bone. 

Note: These things can sound scary, but not all of these require surgery, and it is important to get a proper assessment to determine the appropriate plan of action! 

The above names are sometimes used for rotator cuff injuries, but more commonly, people will be told they have rotator cuff tendinitis

But what is that? It simply means that the tendon(s) of the rotator cuff are inflamed (the ending ‘-itis’ means ‘inflammation’). Remember, the tendon is what attaches the rotator cuff muscle to the bone (see above pictures).

My Shoulder Hurts, But Other Things Also Hurt 

I’m going to keep this section short, because I could probably write an entire blog post on this point alone. But I want to mention that in many cases, it is completely normal for a rotator cuff injury to cause pain in your neck muscles, or down your arm (even as far as your hand in really bad cases). This pain is called referred pain, in which your rotator cuff refers pain to other parts of your body


Not sure if your shoulder pain is related to your rotator cuff? Curious about why you also have pain elsewhere? Want to get out of pain, and back to function? The best thing to do is to get your shoulder assessed as soon as possible. At Strive Physiotherapy and Performance, we are committed to providing an in-depth assessment to ensure we can work together to find the best plan of action for each individual client. Call us at 519-895-2020, or use our online booking tool on to book an appointment with one of our knowledgeable physiotherapists, and they will be sure to help you understand your injury. 

Take care,

Tyler Allen
Physiotherapist at Strive Physiotherapy and Performance


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