The position of our shoulder blades (scapula) on our trunk is hugely important. As infants, our spinal curves are influenced by time spent in tummy time, sitting and standing, and miraculously, by the time we are walking, the back extensor muscles become strong enough to support our head and trunk. The four spinal curves of our neck, upper back, lumbar and sacrum develop and become vital for our mobility and movement. As we go through life, our individual spinal curvature is influenced by heredity, habits, personality, activity and occupation among other factors. Regrettably, continued suboptimal sitting and standing alignment causes our shoulder blades to protract (roll) forward; causing chronic neck, shoulder, upper back, and even lower back pain as the shoulder girdle can no longer efficiently support our neck and head.
At it’s most dramatic, poor positioning of the scapula on the posterior thoracic wall can decrease shoulder flexion (forward reach) increase kyphosis (rounded upper back), forward head/neck thrust, collapse the chest and reduce the capacity for a full tidal (breath) volume. Glen Gillen, an Occupational Therapist and Columbia University Professor emphases the importance of scapula gliding and correct positioning in his course Treatment of the Neurologic Upper Extremity Function and Management when working with individuals who have reduced function due to a stroke or other neurological issues. In yoga asana practice, the spine moves in all six directions, and the scapula are brought “down and on” the back in order to support the health of the spine and functional upright posture. The upper back moves in, the chest lifts up, the ears are over the shoulders.
First some basic anatomy: the shoulder joint itself is called the glenohumeral joint and the head of the humerous (upper arm bone) sits in the shallow socked called the glenoid fossa. The clavicle (collarbone) is the only bone that connects the arm to the trunk. The scapula is a triangular flat bone, which covers the 2-7th rib on the posterior thorax. It has a medial (close to the spine) border, a lateral border, and three corresponding angles; superior, inferior and lateral. The scapula is like the mobile base of the arm; in order for the arm to go up well, the scapula must be down. The scapula moves with a gliding action on the back of the thorax, and is attached to the trunk by muscles. What muscles need to get stronger? What muscles need to stretch? How can my scapula positioning improve?
The middle trapezius, the rhomboid major & minor, and the latissimus dorsi perform scapula retraction, an essential action for healthy shoulders. Another important movement is scapula depression, which is performed by lower trapezius, latissimus dorsi, the serratus anterior (inferior part) and the pectoralis major and minor. Downward rotation is caused by the levator scapula, rhomboids, latissimus dorsi and pectoralis minor and major.
My next blog will provide exercises and strategies to strengthen those three actions of scapula retraction, depression and rotation. However, until then, imagine your shoulder blades are full, and their weight is gently pulling your upper back down as your chest rises and collarbones spread. If sitting, consider placing a rolled up towel behind your lower/mid back to assist with the upward lift of the chest.
Read part 2.