Female yoga student practicing vasisthasana side plank pose.

Stabilizing Your Shoulders: The Anatomy of Good Shoulder Alignment

Rachel Scott, E-RYT 500, YACEP
Updated: 
December 27, 2020

In contrast to how we typically move in the world, in yoga practice, we often bear weight on our hands. Weight-bearing through the upper body has many benefits: increased body awareness, development of strength in the shoulders, arms, and wrists, and development of our capacity to do fun pose like arm balances and inversions. However, because the structures of the upper body are not designed to carry our body weight, it is important for our longevity and functionality to understand how to support ourselves safely through the shoulder when practicing and teaching.

The Structure of the Shoulder

Anatomical image of shoulder joint.

The shoulder joint is a ball-and-socket joint between the humerus and the shoulder blade (scapula). The term "glenohumeral" sounds like a mouthful but is actually literal: the "socket" where the humerus meets the scapula called the glenoid fossa. Put "glenoid" and "humerus" together, and you have a "glenohumeral" joint. 

There are several other joints implicated in the movement of the arm: the joint between our sternum and our collarbone (clavicle), the joint between our clavicle and our scapula, and finally, a "functional joint" between the scapula and our back ribs (scapulothoracic joint). The symphonic combination of these joints moving together creates healthy movement at the shoulder and sets us up for proper weight bearing through the arms. 

Try it: place your fingertips at the juncture between your sternum and your clavicle and move your opposite arm in all directions; you will be able to feel how the bones articulate together to make movement possible. Also note: this is the only location in which there is a bony connection of the shoulder girdle complex to the center of the body! 

Scapulohumeral Rhythm

Although all four joints of the shoulder girdle work together to facilitate movement, the orchestra of movement between the glenohumeral joint and the scapulothoracic joint has a specific name: scapulohumeral rhythm. In a nutshell, these two joints are like dance partners that move together in order for us to move our arms. Without the scapular movement, the movement of the humerus is incredibly limited. 

Try it: come into a comfortable seat and tune into the feeling of your scapula on your back. If possible, have a friend place his or her hands on your shoulder blades to increase awareness of where they are on your back. Now, try to move your arm—without moving your shoulder blade. You won't get far! The moral of the story is that the functional movement of the arm requires the shoulder blades to also move. 

Relevance To Yoga Practice

When we move our arms in yoga practice, we must allow the scapula to glide freely on the back. When we lift our arms overhead—as we might in Surya Namaskar (Sun Salutations) or Adho Mukha Svanasana (Downward Facing Dog Pose)—the inner borders of the scapula move down, the outer borders move up, and the scapula moves slightly apart. However, a common yoga cue is to "squeeze the shoulder blades together," which is contrary to the joint's functionality. When we understand that the scapula must move with the arm bone, then we can practice and teach more effectively to support healthy movement.

Anatomical image of shoulder joint.Stability and the Shoulder

The glenohumeral joint is not intrinsically stable. Compared with the shape of the hip joint (which is fairly deep), the glenoid fossa is quite shallow. Imagine a basketball resting upon a dinner plate, and you get the idea! While this lack of bony stability makes it possible for us to move our arms freely—certainly useful when we consider the perks of reaching into the world and moving our arms in all directions—this lack of bony stability means that support must come instead from muscles. These muscles are called the rotator cuff.

The Rotator Cuff

Anatomical image of the shoulder joint.

The rotator cuff consists of four muscles that reach out and hug the humerus to the scapula. They both stabilize and mobilize the joint. However, they are not "power muscles." Too often in yoga practice, we rely on these small muscles to work without recruiting the larger muscles of the chest and back. A well-coordinated and a functional rotator cuff will help us to position the humerus optimally in the socket. At the same time, we use the larger muscles of the chest and back to stabilize the scapula and support our weight. 

Scapular Stability

Anatomical image of rhomboid muscle group.

Now that we understand the structure of the shoulder joint, let's look at two of those larger muscles that help stabilize and move the scapula. When we are on our hands or upside down, our shoulder girdle becomes the weight-bearing girdle. Stability and awareness of the shoulder blade create the necessary stability for us to weight bear through this structure. 

Although many muscles play a role in stabilizing and mobilizing the scapula, the two key muscles of scapula stability are the rhomboids and the serratus anterior. These muscles essentially play a tug of war with the scapula: the rhomboids pull the scapula toward the spine, while the serratus anterior pulls the scapula away from the spine around the ribcage. 

 

Anatomical image of the serratus anterior muscle group.

Try it: come onto all fours as if you are going to do Marjaryasana-Bitilasana (Cat-Cow Pose). Rather than Cat-Cow, however, we are going to do a "scapular push up." Keeping your arms straight, melt your chest toward the floor so that your shoulder blades squeeze together toward the spine. Then, press through your hands and press your upper back to the sky so that your shoulder blades move apart. Repeat this action several times until you can sense the movement of the shoulder blades as well as the engagement of these two muscle groups. 

Once you have mastered this action in a relatively non-weight bearing position, try a few scapular push-ups in Phalakasana (Plank Pose).  

When we are trying to stabilize the scapula on the back, we need both the rhomboids and the serratus to do their job; when they fire together, they anchor the shoulder blade against the back. As we coordinate this stability with engagement through the rest of the body (core engagement and leg awareness), we will begin to become better adept at weight bearing through the hands. A handy set of cues that I frequently use with my students to recruit this set of muscles: "spread your shoulder blades apart" (activates serratus) "as you broaden your collarbones" (activates the rhomboids). 

In your practice, seek to stabilize the scapula on your back before bearing weight through your shoulder girdle. An excellent time to practice finding this stabilization is just before you lower from Plank Pose to Chaturanga Dandasana (Four-Limbed Staff Pose). This transition is often rife with challenges. Without good scapular stability, the shoulder heads may fall forward, leading to a non-optimal positioning of the arm and adding too much weight to the front of the shoulder. Rather than move through this transition quickly, take time to establish scapular stability. Work on your knees if that helps. By taking the time to set yourself for proper movement patterns first, you create a yoga practice that is sustainable over time.   

Final Thoughts

As you move forward in your practice and teaching, explore increasing your awareness of the connection of your humerus to the scapula and your scapula to your back body. First, strengthen your understanding of these relationships in non-weight-bearing poses, then gradually add more load to the upper body as your muscles become more entrained to functional movement. Through the patient cultivation of strength and stability, you will build a solid foundation for your practice and set yourself up to safely explore more exotic hand balancing poses and inversions.

 

Tom Myers, YogaUOnline presenter, wellness, yoga and fascia, lifelong mibility

 

Rachel Scott, Writer, Yoga teacher, yoga trainer, coachRachel helps yoga teachers and studios around the world create transformational education experiences so that they can thrive in their business, share their passion, and inspire more people to practice yoga. Her extensive knowledge and experience include earning two master's degrees, authoring five books, leading over twenty 200-hour teacher trainings, building a teacher training department for a national yoga studio, and working in yoga studio management for more than fifteen years. She combines her extensive practical experience with her academic expertise (Masters in Instructional Systems and Learning Technology) to help yoga teachers and studios develop quality, transformational in-person, and online educational programs.

As a yoga expert, has written for periodicals such as Yoga International and the Huffington Post, made guest appearances on CTV, Breakfast Television, and numerous podcasts, and presented at venues such as Wanderlust, Omega Institute, and several international yoga conferences. She exuberantly shares her knowledge and skills through coaching, her blog, YouTube channel, and free online classes. Find her at rachelyoga.com or on social media at rachelscottyoga.