by julee snyder
We’ve already talked about the shoulder girdle which consisists of the scapula and the clavicle. In that post, we looked at the six movements of the scapula: elevation, depression, protraction, retraction, upward and downward rotation. Now we turn our attention to the shoulder joint, more specifically the glenohumeral joint. This is a ball and socket joint consisting of the head of the humerus within the glenoid fossa of the scapula.
The glenoid fossa is a shallow socket designed more for mobility than stability. Because the joint is so shallow, it is extended by a fibrocartilage ring attached the fossa margins called the glenoidal labrum. The muscles of the rotator cuff (supraspinatis, infraspinatis, teres minor, and subscapularis) work to stabilize the shoulder socket.
There are six movements of the shoulder joint: flexion (raising the arms over head), extension (bringing the arms back to your sides from flexion), abduction (taking your arms out to the sides away from midline), adduction (returning the arms back toward the midline), external rotation, and internal rotation. During your next practice, ask yourself what movement your arms are doing in each pose.
When the shoulder blade is well situated on the rib cage and the muscles around the shoulder socket well-balanced, the head of the humerus will draw down and rotate as the distal end arcs upwards through space. This keeps equal joint space on all sides of the joint and is protective. If there is a muscle imbalance, the head of the humerus will not drop down so that when the arm elevates there is compression of the structures that travel between the humerus and the acromium.
As yogis, we must be careful not to over-strain or over-stretch the joint, especially in weight bearing positions. Begin to notice if you are hanging into the ligaments and tendons of your shoulder joints, especially in weight bearing poses. It is very common in downward facing dog. We’ll talk more about the dome of the armpit in another post, but begin to feel that your armpits are both yawning open while also being buoyantly lifted by imaginary helium balloons floating underneath. This will keep you from dropping too deeply and instead demand that you stabilize through your muscles around the joint.
Many activities build strength in certain areas and not in others. And because yoga does not offer much opportunity for pulling in the arms, the muscles around the joint can sometimes be out of balance. Plus many in our culture have forward scapular position. Both of these things makes our shoulders more vulnerable to injury. There is a lot to know about shoulders as they are very complex. If you are having trouble, I encourage you to seek advice from a trained professional. Theraband exercises, stability ball exercises, Pilates and more can offer a great balance to your yoga practice.