The shoulder is one of the most misunderstood joints of the body. It can be susceptible to injury in yoga because we often demand a great deal of work from it that it is not designed to do. It has been a long time since we walked on all fours, but in yoga we act like our arms are intended to bear weight just as our legs are. This is not the case. In fact the shoulder is not really one joint, but a complex that includes three joints: the sternoclavicular joint (collarbone at the sternum), acromioclavicular joint (shoulder blade at the end of the collarbone) and the glenohumeral joint (arm bone at the shoulder blade). The glenohumeral joint has the greatest freedom of movement of all our extremities which can be advantageous when trying to achieve Upward Bow Pose /Dhanurasana, but can also predispose us to injury. The arm bone ends in a ball-like shape that fits into a socket in the shoulder blade. The shoulder blade sits on the rib cage and hooks over the top to connect with the collarbone forming a small ligamentous attachment. The only other bony point of attachment for the shoulder is at the sternoclavicular joint, where the collarbone then meets the sternum. Otherwise the bones are essentially free floating, under the protection of ligaments and muscular attachments.
The Rotator Cuff: More like a rotator crew
The rotator cuff is one of these protective muscular groups. The name is misleading though. It is not one singular cuff, but a group of four muscles that each exert a supportive role in four different directions on the glenohumeral joint. The supraspinatus muscle sits in the top portion of the shoulder blade and resists downward motion of the arm bone. The infraspinatus and teres minor sit in the bottom portion of the shoulder blade and resist backward motion. The subscapularis muscle is on the opposite side of the shoulder blade, in contact with the rib cage, and resists forward motion of the arm bone.
Two of these muscles are vulnerable to pinching or impingment: the supraspinatus muscle and the subscapularis muscle. Overhead movements with the arms or repetitive pushup /chaturanga motions can contribute to this injury, causing the tendon of the muscles to become pinched between bone. We can avoid this by using a certain amount of scapular retraction when we move. Retraction is the action of the shoulder blades moving closer to one another and nesting on the rib cage (versus the inner line of the scapula ‘winging’ off of the rib cage). Cues from our teachers such as “head of the arm bones back”, “shoulder blades on the back” or “squeeze the shoulder blades together” are attempting to create space for the supraspinatus and subscapularis.
An important muscle that helps support the rotator cuff in shoulder stability exerts its control on the scapula instead of the humerus bone of the arm. The serratus anterior attaches from the rib cage, under the scapula the inner border. It supports a push or punch motion by stabilizing the shoulder blade on the rib cage. This is easier said than done. In most cases of shoulder dysfunction, the serratus anterior has become weak and underused. Luckily it can be easily strengthened through a “plank plus” exercise.
To strengthen the serratus anterior come into a plank pose (push up position) with wrists lining up with the end of the mat, hands shoulder width apart, stacked under the shoulders. Let the heart melt towards the floor so that the spine is in neutral and you are not rounded between the shoulder blades. Let the spine stay exactly as it is for the duration of the exercise. You may practice this from your feet (legs extended, feet hip width apart) or from your knees (hips extended as you would for a knee push up). The motion is subtle and may take practice to establish the mind body pathways so use patience and remember not to round your spine. Root the balls of your hands at the base of each finger and press into your hands imagining the arm bone moving out of its socket towards the earth. Slowly reverse this motion imagining the arm bone moving towards your back body into its socket. Try not to engage the meat of the shoulder, the upper trapezius muscle, by shrugging. The thoracic spine between the shoulder blades does not move. Repeat this motion. You may begin to feel a sensation at the bottom of your arm pits as the serratus anterior starts to tire.
Riddle Me This
The shoulder can be quite complicated but it doesn’t have to be a complete mystery. Understanding that the shoulder is designed for mobility, not stability and supporting the muscles that support our shoulder, can lead to a happier and more engaged yoga practice.
Dr. Robin Armstrong has combined her decade of experience as both a Chiropractor & Yoga Instructor to develop a unique type of yoga therapy known as Yoga Rehab, blending traditional yoga practices with modern rehab exercise to help students overcome pain and injury. She has shared her knowledge of yoga injury prevention and anatomy with the Canadian Press, American Council of Exercise, Impact, and Alive magazines as well as many local yoga teacher training programs. She practices at YYoga Downtown Flow studio in Vancouver, Canada.
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