Archive for January, 2013

1 January

The Shoulder


The Amazing Moveable Shoulder Girdle

Your shoulder girdle is one of the most movable and capable joints in your body.  Unlike the hip joint that is the typical ball and socket joint that allows you to stand and walk all day long,  the shoulder girdle does not have as much stability as the hip socket.  What it lacks in stability, it makes up for in mobility.  The shoulder girdle is designed to be strong, but more so, to move in all possible directions.  Try moving your leg in all directions, then move your arm in all directions.  Do you notice a difference?

Anatomy of the Shoulder Joint

The shoulder is made up of three bones that create what is called the glenohumeral joint.  The bones that create the shoulder are the humerus, scapula and clavicle.  The only bone to bone connection is at the sternoclavicular joint, where the sternum and clavicle connect.  The scapula lies on top of the ribcage connected by soft tissue, and the humerus lies in the glenohumeral joint cushioned by the subacrominal bursa under the acromion.  See picture below.

Movement of the Glenohumeral Joint

As mentioned before, the movements of this joint are highly complex and therefore need to be well coordinated in order to prevent injury.  The first thing to know about your shoulder girdle before you start to move it, is that it is a lever system.  As your arm moves upward, something needs to counter the action by moving downward.  In this case, the scapula needs to move downward.  In the Pilates world, we call this anchoring the shoulder girdle.   Anchoring means allowing the shoulder girdle to drop down toward the pelvis, and open the front of the shoulder girdle.  Looking at yourself from the front, when you anchor your shoulder girdle, your shoulders are not in your ears and your clavicles are parallel to the ground.  This is an anchored and neutral position of the shoulder girdle.

Once you find this neutral anchored position of the shoulder girdle, you are ready to move.  There is so much movement in the shoulder girdle, that it is designed with three changing axis of movement.  The axis of movement changes as you want to increase your range of motion.  So, your coordination and understanding of this joint is paramount.

The first axis of movement is the humerus rotating around the scapula at the glenohumeral joint.  The second axis of movement is the scapula rotating around the clavicle at the acromioclavicular joint.  These two axis of movement bring your arm to a little above ninety degrees to the ground.  The last axis of movement is the clavicle rotating upward at the strenoclavicular joint.  This brings your arm over the top of your head like Caroline’s serve on the title page.  Take a moment to move your arm from by your side to over your head and see if you can feel the change of axis of movement.  First, the humerus, then the scapula and lastly, the clavicle.  Without using all three, you will have a decrease in your range of motion, or potential for injury.












Rotator Cuff

No shoulder class is complete without talking about the rotator cuff.  The rotator cuff is a group of four muscles that connect from various points on the scapula to the humerus.  The rotator cuff coordinates the movements of the scapula and the humerus.  As you may have realized from the last portion of the class, that means that this group of muscles need to be well versed in the movements of the glenohumeral joint.  The four muscles of the rotator cuff are the teres minor, the supraspinatus, infraspinatur and subscapularus.  The first letter of each of these spells out the work sits.  Sometimes this

group of muscles is referred to as the sits muscles.  The only muscle that is not shown in the picture is the subscapularus that lies underneath the scapula.

To make sure that these muscles are working correctly.  Make sure the you stick to the three axis of movement.  The two axis of movement that often do not get used to their fullest are the movement of the scapula and clavicle.  So,  when you move your shoulder, make sure you allow the scapula and then the clavicle to move.  If you notice that it is not easy to get your scapula to move, you may want to add some scapula exercises to your exercise regime.  Bring your arms in front of you, parallel to the ground with palms facing each other.  Keep the arms long, and bring the scapula together and apart.   Also check that your shoulders are anchored most of the day, and that you incorporate all three axis of movement in the shoulder girdle.  These types should keep your shoulders happy and healthy for years!