Your arm has to be able to move out away from the body (abduction), forward and backwards, and to be able to rotate internally and externally.

After last week, when we were laying flat on the floor with our arms in a Cactus or T-shape with the forearms by the temple area, we found many could not externally rotate the arm in the socket enough to get the back of the wrist on to the ground. We decided there and then that next week’s class would be to work on the external rotation (turning outward) of the arm bone in it’s socket.

Your upper arm muscles are the Deltoid, Biceps and Triceps.

The shoulder is a ball and socket joint, just like the hip joint and this arrangement of the humorous (arm bone) into it’s socket (Glenoid Fossa) allows for a very large range of movement. However, the socket element is a less deep than the hip joint and therefore more prone to injury. In order for the shoulder to function properly, the ball needs to be seated securely and squarely into the socket. Most shoulder pain is caused by this not happening properly. The most common type of injury I see in my private work and in class is caused by an impingement of one of the Rotator Cuff Muscles. In the worst case scenario, this can lead to a rotator cuff tear which may require surgical intervention.

This is caused by weakness in the Rotator Cuff muscles and / or by a rounded upper back posture (stooping). Try now to reach up overhead whilst you are stood with a rounded upper back and the tailbone tucked under. A mechanical block occurs in this position and the arm will not be able to go to it’s fullest range of motion. As soon as you stand fully upright, with a natural lordosis in the low back, your arm will go straight up overhead (180 degrees) and even slightly behind you if you are flexible. So to treat an impingement, we need to work on having an open chested posture so that the head of the humorous can rotate fully in the socket.

The Rotator Cuff Muscles* are just as they sound – a cuff, like the sleeve of your cardigan, which secure the ball into the socket with enough room to rotate around, especially for the action of reaching up and overhead to occur. Tarise from the Scapula and connect to the head of the humerus (arm bone). If there isn’t enough space, the arm bone bumps into the roof of the shoulder blade (AC Joint) and pinches the muscles, stopping the full range of motion from occurring. This pinching is called impingement. If the RC muscles are weak, they are unable to keep the ball down in the socket. Their job is to compress the Gelnohumeral Joint to allow the large Deltoid Muscle to further elevate the arm. Weakness in the Rotator Cuff Muscle is another common cause of shoulder pain and restriction.

We are most prone to Rotator Cuff Injury if we repeatedly make actions such as throwing or making a pulling or swinging motions with the arm which can sometimes happen whilst gardening if we aren’t strong enough in the muscles to pull off the repeated action.

For a healthy shoulder joint, we need to have an open chested posture so that we create more room for the arm to rotate in the socket. This requires the front of the shoulder (the anterior capsule and the pectorals minor muscle) to be released so that we can pull the shoulder blades toward each other (engaging and strengthening the Rhomboids) and tuck them downwards (as if we were putting them in a back pocket).

Names of Rotator Cuff Muscles:

All Stabilise the arm at the Glenohumeral (shoulder) Joint

Supraspinatus – Abducts (moves are out and away from the torso)


Infraspinatus – Laterally rotates, transversely abducts


Tres Minor – as infraspinatus.


Subscapularis – Medially rotates

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