Try this quick multiple-choice test. When you teach your students how to reach their arms high overhead, should you (a) tell them to pull their shoulder blades down toward the floor, (b) tell them to lift their shoulder blades up toward the ceiling, or (c) throw up your hands in confusion and say "I don't know what you're supposed to do with your shoulder blades?" If you've taken enough yoga workshops with enough different teachers, choice (c) might seem the most natural to you. Some teachers insist that when you lift your arms up you must hold your shoulder blades down at all costs, while others are equally adamant that you must raise your shoulder blades as high as you can. To solve this confusion, this column will advocate choice (b), lifting, but only if it's done in a certain way, which, paradoxically, involves a good bit of downward pull. Why go with (b)? The action of lifting will help protect your students against rotator cuff injuries, give their arms maximum height, and make it much easier for them to progress from arm elevation to backbending movements of the arms and shoulders, like those required for Adho Mukha Svanasana (Downward Facing Dog Pose) and Urdhva Dhanurasana (Upward Facing Bow Pose).
To understand how to teach your students to lift their arms freely, it helps to know some basic shoulder anatomy. The shoulder blade, or scapula, is shaped roughly like a right triangle with its point facing downward, its inner (medial) edge running vertically alongside the spine (vertebral column), and its top edge running horizontally. The medial edge is called the vertebral border of the scapula. The upper-inner corner of the shoulder blade, at the top of the vertebral border, is called the superior angle. The lower tip, at the bottom of the vertebral border, is called the inferior angle. The most prominent feature of the top edge of the shoulder blade is a horizontal ridge of bone that runs along its length. This is the spine of the scapula, and it is palpable just under the skin if you reach one hand across your body to touch the top-rear part of your opposite shoulder. The outer end of this ridge, at the upper-outer corner of the scapula, is called the acromion process. Recessed under the acromion is the glenoid fossa, a slightly concave circle of bone the size of a small coin.
The shoulder blade is capable of several of movements. Abduction (also called protraction) is the movement of the scapula away from the midline of the body and around toward the front. Adduction (retraction) is the movement toward the midline. Elevation is the vertical lifting of the scapula. Depression is the downward push. Anterior tilt is the tipping of the top edge of the scapula forward and the inferior angle backward. Posterior tilt is the tipping the top edge backward and the inferior angle forward. Upward rotation is a more complex scapular movement. The inner edge of the scapula moves down while the outer edge moves up, so, when viewed from the rear, the whole bone turns either clockwise (left scapula) or counterclockwise (right scapula). Upward rotation is crucial to arm elevation. To understand why, let's consider the upper arm bone (humerus), and its relationship to the shoulder blade.
The top end of the humerus has a rounded head that sits under the acromion process of the scapula and abuts the glenoid fossa. The junction between the glenoid and the humeral head is the gleno-humeral joint. This joint allows most of the familiar arm movements at the shoulder, including abduction (reaching the arm out to the side), adduction (moving the arm across the body), flexion (bringing the arm forward), extension (bringing the arm backward), internal rotation (turning the arm in) and external rotation (turning the arm out). However, all of these movements can be enhanced by supportive movements of the scapula, and one arm movement, elevation (lifting the arm overhead), cannot be accomplished at all by movement at the gleno-humeral joint alone. It also requires strong upward rotation of the scapula.
When a student brings her arm from straight down at her side to straight up overhead, she lifts it through an arc of 180 degrees. However, even under the best of circumstances (that is, strong external rotation of the humerus), the gleno-humeral joint only allows about 120 degrees of arm lift. The remaining 60 degrees come from upward rotation of the scapula. Last month's column explained that it is important to turn the humerus outward while lifting the arm upward in order to help prevent pinching one of the rotator cuff tendons (the supraspinatus tendon) between the head of the humerus (below it) and the acromion process (above it). If the arm is not turned outward, it can only lift about 20 to 30 degrees before the bony outer side of the humeral head (called the greater tubercle) jams against the acromion and pinches the supraspinatus tendon. But even with maximal outward rotation of the arm, the greater tubercle starts jamming against the acromion (and pinching the supraspinatus tendon or nearby structures) at about 120 degrees of lift. The only reason the typical student can raise her arm all the way to 180 degrees is that she unconsciously rotates her scapula upward as her humerus tilts up. This tips her acromion up and out of the way of her humeral head so her arm can reach the vertical position without impingement.
Upward rotation of the scapula during arm elevation is produced automatically by nerve firing patterns that are programmed into the brain and spinal cord. To understand just how deeply ingrained these patterns are, try this. Stand in Tadasana with your right arm hanging at your side and your left hand reaching across your body so it rests atop your right acromion. Then start to reach your right hand out to the side, as if starting to bring it up overhead. Notice that your hand doesn't get far at all before your acromion starts to lift! Even if you try to prevent upward rotation by pulling your outer right shoulder blade strongly downward and turning your arm strongly outward while lifting your hand, it's very difficult to get your arm above horizontal without raising your acromion. This provides a clue that will help us answer our initial question. Should we instruct our students to pull their shoulder blades down or to lift them up when they raise their arms? From what we just observed, even if they try to pull them down, at least the outer edges will lift up anyway as the arms go up. This is a good thing, because if their acromion processes didn't lift, their supraspinatus tendons might be pinched, and they couldn't raise their arms all the way to vertical. So it makes sense to recommend, at the very least, that students lift the outer sides of their shoulder blades when they take their arms up.
This brings up a practical question. Is it anatomically possible for a student to voluntarily elevate the outer edge of her shoulder blade more than the inner edge? The answer is yes, absolutely. Here's why: the two main muscles that elevate the shoulder blade are the upper fibers of trapezius and the levator scapulae. The upper trapezius runs from the middle of the back of the neck and the base of skull to the outer end of the collarbone (clavicle). The end of the collarbone, in turn, is attached to the acromion. Therefore, when the upper trapezius contracts, it pulls the outer clavicle up, which in turn pulls the acromion up, which lifts the whole outer shoulder blade, leaving the inner shoulder blade behind. The upper fibers of trapezius therefore help upwardly rotate the scapula.
The levator scapulae does something quite different. It runs from the side of the neck (transverse processes of the upper cervical vertebrae) to the upper inner shoulder blade (the superior angle). When it contracts, it selectively lifts the inner border of the scapula and leaves the outer border behind. This means it performs downward rotation, which is just the opposite of what our students need for lifting their arms overhead. When contracted too hard, it also bunches uncomfortably at the base of the neck (see right photo). Therefore, it makes sense to discourage students from activating this muscle while they lift their arms. However, as we'll see, contracting the levator scapulae moderately can be helpful for maximizing final elevation after the scapula is rotated completely upward (see middle photo).
We're getting closer to formulating specific instructions we can give to students to get their arms overhead most effectively. These instructions will include lifting the outer shoulder blades up without actively lifting the inner shoulder blades, but this is not the whole story and it would be misleading to stop here. To complete the tale, we need to look at the anatomy of the trapezius.
The upper fibers of the trapezius alone are not sufficient to upwardly rotate the scapula. The middle trapezius, lower trapezius, and serratus anterior are also needed. The middle trapezius runs roughly from the vertebral column between the shoulder blades to the acromion process. Its action picks up where the upper trapezius leaves off. When the scapula is rotated partially upward, it pulls the acromion horizontally toward the vertebral column, and thus continues the rotation.
The lower trapezius runs from the middle of the vertebral column below the shoulder blades (that is, from the spinous processes of the lower thoracic vertebrae) upward to the medial end of the spine of the scapula. When it contracts, it pulls the inner margin of the scapula down, thus complementing the lift of the outer margin of the scapula produced by the upper and middle trapezius. The net result of all three parts of the trapezius working together is upward rotation of the scapula without elevation or depression. The downward pull of the lower trapezius on the inner end of the spine of the scapula is especially important because it provides an axis around which the whole scapula can upwardly rotate. Since the lower trapezius actually does apply a downward force to the inner shoulder blade, it makes anatomical sense to instruct your students to actively draw their inner shoulder blades downward when you want them to rotate their scapulae upward as they lift their arms. However, this action will eventually be eased when it comes time for final elevation of the shoulder blades.
It takes some imagination to visualize the complex course and actions of serratus anterior. This muscle originates on the front-side ribs of the mid-to-lower chest, runs backward around the body, passes underneath the shoulder blade, and attaches to the underside of the vertebral border of the scapula. When it contracts, it pulls the whole shoulder blade away from the vertebral column and around toward the front of the body (that is, it produces scapular abduction), but it abducts the lower end farther than the upper end, creating upward rotation of the scapula. Its contribution to upward rotation is so great that without it, it is impossible to lift the arms completely overhead. Its abducting action is also crucial for offsetting the adducting actions of all three parts of the trapezius.
When instructing your students in how to lift their arms, it is important to communicate the need to strongly activate this scapular abductor. To help your students fully engage their serratus anterior muscles, encourage them to roll their shoulder blades apart and around toward the front of the body while they lift their arms. This instruction will become even more important during the final elevation phase of lifting the arms.
So what is this final elevation phase? So far, we've implied that it's a good thing without explaining exactly what it is or why it's desirable. To understand what it is, it's useful to compile the instructions we've collected so far into a coherent sequence, and see where they leave us. Try this: Stand in Tadasana. Cinch your arms downward and rotate them outward as far as possible. Begin lifting your arms to the sides, continuing to rotate them out. Draw your inner shoulder blades downward, but let your outer shoulder blades rise as your arms lift. As your arms continue above horizontal, roll your shoulder blades apart and around toward the front of your body. Continue the same rotation of your arms, the same downward action of your inner shoulder blades, the same upward action of your outer shoulder blades, and the same rolling of your shoulder blades apart even after your arms reach the full vertical position. But what should you do next? The best way to understand this is with a demonstration.
Follow all the instructions in the previous paragraph. When your arms are pointing straight up, pull your inner shoulder blades down even more strongly. (If you want to make this demonstration even more dramatic, hold both the inner and outer shoulder blades down, as in the left photo.) Now, continuing this downward pull, try to move your hands and arms backward as far as you can without bending your elbows (that is, move your arms toward the position they might take in a full backbend like Urdhva Dhanurasana). If you are like most people, your response to this last instruction will be "Yuck! It jams my shoulders! My arms won't move back!"
Now try an alternative. Return your arms to the straight up position with the inner shoulders pulling down. Roll your shoulder blades apart as far as you can. Now gradually let go of most of the downward pull as you lift both shoulder blades upward. Lift the outer side of each shoulder faster than the inner side at first, but eventually lift the whole shoulder blade, inner and outer, as high as it will go. If you do this carefully, your levator scapulae muscles will engage modestly, but so will your upper trapezius, while your lower trapezius remains slightly active. With this combination of muscle contractions, you won't lose any of the upward rotation of your scapulae; instead, you'll probably enhance it while you elevate both shoulder blades in the upwardly rotated position. After your first lift, roll your shoulder blades apart once more, then lift them even further. You'll probably find that the higher you lift your shoulder blades, the more they move toward one another. This is because both of the lifting muscles, the upper trapezius and the levator scapulae, are also adductors, especially when the scapulae are high. Actively using serratus anterior to try to abduct the shoulder blades as you lift them will help prevent a bunching of the levator scapulae at the base of the neck and will enhance upward rotation.
When you have lifted your shoulder blades as high as you can, keep them up while you take your arms backward as far as possible into the backbending position you tried before. This time, if you're like most people, you will have much more freedom in the backbending movement, in sharp contrast to the restriction you experienced when you held your scapulae down. It's not clear why this happens, but it may be that lifting the shoulder blades so high while in full upward rotation frees them to tilt much farther posteriorly than they can when they are pulled down. This tilt would point the gleno-humeral joints backward, making it easier to reach the arms back.
So we can sum up the rationale for lifting the shoulder blades while reaching the arms overhead as follows: Lifting the outer shoulders more than the inner shoulders rotates the scapulae upward. This angles the acromion processes upward, making it easier to reach the arms straight up without impingement. Once the scapulae are rotated completely upward, elevating them as high as possible without losing their upward rotation creates maximum space for tilting them backward. This posterior tilt angles the gleno-humeral joints backward, making it easier to move the arms into a backbending action.
Although the anatomical explanation of why to lift the shoulder blades while lifting the arms is complicated, it's worth taking the time to think it through and explore it in your practice so you can share it with your students. Lifting the arms high is a universal expression of jubilation. When you help your students do it freely and fully, you help them find not just mobility, but also exhilaration and joy.
Left photo. Pulling the shoulder blades down while lifting the arms prevents full upward rotation of the scapulae, encourages rotator cuff impingement, and makes it difficult to move the arms backward into a backbending position. (view photo)
Center photo. Lifting the shoulder blades up as high as possible after rotating them completely upward safely raises the hands to maximum height and frees the arms and shoulders for backbends. It's important to move the shoulder blades apart while lifting them up to maintain upward rotation and to reduce bunching of the levator scapulae muscles near the neck. The angle of the vertebral border of the scapulae reveals greater upward rotation in this photo than in the right and left photos. Note also the difference in the height of the hands in the three photos. (view photo)
Right photo. Contracting the levator scapulae muscles too soon during the process of raising the arms or too hard after the arms are up causes the muscles to bunch uncomfortably at the base of the neck, prevents full upward rotation of the scapulae, encourages rotator cuff impingement, and restricts backbending action of the arms. (view photo)
Roger Cole, Ph.D. is an Iyengar-certified yoga teacher (http://rogercoleyoga.com), and Stanford-trained scientist. He specializes in human anatomy and in the physiology of relaxation, sleep, and biological rhythms.