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Shoulder Anatomy 101: A Yogi's Beginner Guide to the Shoulder Girdle
While you don’t need an in-depth anatomical description of the shoulder girdle, having at least a basic understanding of the structure of your shoulders, as well as a few key alignment principles, will help you work more efficiently and find more ease in your yoga practice. Plus you’ll have a much easier time following your teacher’s instructions!
To help get you started, I’ve put together this beginner’s yoga resource—a basic guide to understanding the shoulder girdle—beginning with the bony structure.
The Shoulder's General Bony Structure
When you think of your shoulders what do you think of? The tops of your shoulders that tend to tense up toward your ears? The width of your shoulders across? Or your entire upper back area?
If you said all three, you would be right. The structure of the shoulder girdle is comprised of three bones: your collarbone (clavicle), head of the arm bone (humerus) and actual shoulder bade (scapula).
The long, thin bones that run horizontally out from the base of your neck are called clavicles, or collarbones. They are s-shaped and curve outward slightly at the midline where they connect to the breastbone and inward toward the ends where they lead into the shoulder. Using your fingers, lightly palpate the area around your collarbones. Trace the thin bones from your breastbone out toward your shoulders, feeling the shape of your clavicles.
Your upper arm bone is called the humerus bone. The top, which is the head, of the humerus is shaped like a ball that fits into the socket of the shoulder blade (creating a ball-and-socket joint). You can find the head of your arm bones by placing one hand on top of the opposite shoulder (where a shoulder pad would go) and swinging your arm forward and back, noticing the movement under your hand. Then shrug them up and down. Those are the heads of your arm bones, commonly referred to as your shoulder heads.
Easily located on your upper back, the shoulder blades form the backside of the shoulder girdle attached to both the collarbones and heads of the upper arm bones. They are wide, flat triangle-shaped bones (broad at the top and narrowing into a tip at the bottom) that run over back of your upper ribs and move up and down as well as on and off the back.
3 Major Joints in the Shoulder Girdle
The Glenohumeral Joint
The As mentioned above, the head of the arm bone fits into the cavity of the shoulder blade forming a ball-and-socket joint known as the glenohumeral joint. While you don’t need to know that, what you do need to know is that the socket on the shoulder blade (or glenoid cavity) is fairly shallow and the head of the arm bone sits loosely on top—making this shoulder joint the most mobile (and least stable) joint in the body.
The Acromioclavicular Joint
The junction between the collarbone and the shoulder blade (more specifically the highest point of the shoulder blade known as the acromion process) is the acromioclavicular or AC joint. A gliding joint, the junction allows for the arms to be raised overhead as well as for greater range of upper arm bone rotation.
The Sternoclavicular Joint
The last major joint of the shoulder girdle, and the least talked about, is the sternoclavicular or SC joint between the clavicle (collarbone) and sternum (breastbone), which allows the collarbones to move in three planes, giving the entire shoulder girdle a larger range of motion.
Relationship Between Bony Structures
Now that we’ve located the three bones that comprise the shoulder girdle, lets take a look at how they function together. Here’s what you need to know for beginner’s purposes:
When the heads of the arm bones drop forward the collarbones narrow and the shoulder blades round off the upper back. Try it. Slouch for one moment. Notice what happens to your collarbones and upper arms as your hunch forward. Now lift up through the sides of your chest and move the heads of your upper arm bones back, widen your collarbones and lightly hug your shoulder blades down your back.
The three boney structures move in conjunction to one another. The relationship is such that it’s nearly impossible to place your shoulder blades on your back without taking the heads of your arm bones back and broadening the collarbones. In order to place your shoulder blades on your upper back, the sides of your bodies must first be lifting to allow for the heads of your arm bones to move back and for the collarbones to broaden. Then the outer shoulder blades can lightly hug on and down your back. That’s why you’ll often hear yoga teachers say things like “widen your collarbones,” “heads of the arm bones lifted” and “outer shoulder engaged” in a yoga pose like Downward Facing Dog.
Principles of Alignment for the Shoulders in Yoga
In order to keep the alignment of the shoulder girdle simple for my beginning yoga students, I give them these four easy steps to remember:
Lengthen your side bodies (lifting through your side chests).
Move the head of your arm bones back.
Broaden your collarbones.
Lightly hug your shoulder blades on and down your back.
Stand in Tadasana (Mountain Pose) with your feet under your sitting bones and arms along the sides of your body. Firmly press your feet down into the floor and on an inhalation, lift up through the sides of your body. As you do, lift your chin parallel to the earth. Exhale, and move the heads of your arm bones back. Broaden your collarbones and gently pull your outer shoulder blades down your back. Lightly lift your sternum and take a few deep breaths.
Study with YogaUOnline and Julie Gudmestad: Shoulder Strength and Stability: Serratus Anterior.
Read more about keeping shoulders safe from YogaUOnline and Olga Kabel: Three Essential Steps to Protecting Your Shoulders in Yoga.
Meagan McCrary is an experienced yoga teacher (E-RYT 500) and writer with a passion for helping people find more comfort, clarity, compassion and joy on the mat and in their lives. She is the author of Pick Your Yoga Practice: Exploring and Understanding Different Styles of Yoga a comprehensive encyclopedia of prominent yoga styles, including each system’s teaching methodology, elements of practice, philosophical and spiritual underpinnings, class structure, physical exertion and personal attention. Currently living in Los Angeles, Meagan teaches at the various Equinox Sports Clubs, works privately with clients and leads retreats internationally. You can find her blog, teaching schedule and latest offerings at www.MeaganMcCrary.com