Shoulder Structure, by Physio Dave Boyd

Since we decided to stop walking on all fours and start reaching up into the trees for delicious red fruits, our shoulders have changed from a stable joint (like our hip-a true ball and socket joint), to a mobile and much less stable joint. Having mobility in our upper limbs lets us do lots of cool things like put on make-up and take high-angled selfies. Unfortunately when we have pain in them, they significantly affect our lives, not just because of the cool things we can’t do, but the not-so-cool things like eating and getting dressed also become really difficult tasks. Shoulder injuries are something we see very often here at SAIT. They can be from a traumatic injury, from overuse, or just slowly develop over time. Read on if you have an interest in the basic anatomy and function of the shoulder and the most common presentation we see.

Shoulder Structure

The shoulder is comprised of the shoulder blade (scapula) and the arm bone (humerus). The humerus has a golf-ball sized end on it (without the indentations) which meets with a small, shallow dish (similar to a golf tee) on the scapula. There are 4 main muscles that keep the golf ball (head of the humerus) on the tee (the glenoid fossa). Collectively they are called the rotator cuff and there is:

- One on top (supraspinatus)

- Two at the back (Infraspinatus and Teres Minor)

- One at the front (subscapularis)

When you move your arm, you call upon the big-thugish muscles (deltoids, pectoralis major and latisimmus dorsi, just to name a few) to do the heavy lifting, however they don’t just move your arm, they also create a force inside the joint pulling the golf ball away from the tee. The rotator cuff muscles are constantly cleaning up after these big-thugs by fine tuning the movement and keeping that ball sitting nicely on the tee.

Unfortunately the rotator cuff can easily be overworked over a long period, or just have one bad day and become a bit disgruntled. When they are in this state, they can go on strike either by themselves or with a couple of their workmates (they will even join structures from other departments such as bursae, cartilage and nerves on strike).  This can result in the not-so-bright prime movers mentioned before to start pulling the golf ball off the tee. This can result in pain; pinching pain, shooting down the arm pain and achey shoulder pain just to name a few.

To get these rotator cuff muscles off of strike and back to work, they need a bit of compensation in the form of a TLC pay-out. To begin with this involves hands-on therapy to help them to relax and actually begin negotiating with the guys in the office (the brain) to return to work. However, as they have had some time off, their return to work pathway must be slow and specific for their role. This comes in the form of specific recruitment and strengthening exercises.

Rotator cuff traumatic injuries (falling on your shoulder) or overuse injuries (serving too many 200km/h serves) are not the only type of injuries in the shoulders, there are many other structures around the shoulder that can and do get injured or overused. In almost all circumstances however, the rotator cuff are avid union members and if there is any sign of anyone else going on strike, they’ll also kick up a fuss and join them. So not only are they imperative for mobility and stability, but they are also team players having a significant role in any shoulder pain.

If you think your rotator cuff muscles are on strike, or even discussing the possibility of strike, contact us at SAIT for a thorough assessment and a return-to-work plan.