In this article I wanted to take a closer look at the anatomy of shoulders and how we can use this knowledge to keep safe in Chaturanga Dandasana – a pose sometimes seen as the culprit of many yoga injuries. We’ll begin with a run-through of the main muscles around the shoulder, how they can end up being misaligned, and how to use the muscles to integrate the shoulder joint to keep it healthy and safe in  yoga practice.

Who’s in the shoulder ?tree bone and lots of muscles !

Let’s start with a bit of anatomy. While the hip joint is designed for its stability, the shoulder girdle is known more for its mobility. It is a spacious, shallow joint made up of three bones:

1. Scapula (shoulder blade)
2. Clavicle (collar bone) and
3. Humerus (upper arm bone).

There are many different muscles at work in the shoulder girdle; either holding the three bones together or moving them. We can group these into three categories:

 Rotator cuff muscle –These muscles attach the upper arm bone into the joint created by the collar bone and the shoulder blade. They also move the arm sideways away from the body (as if flapping a wing) and rotate the arm in two different directions.

Muscle that move the humerus bone  (but are not attached to the scapula),and 

Muscle that move the scapula

 

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Rotator cuff muscles

-Supraspinatus  ; main action (humerus abduction ), Example (lift your arms out to the side.

–Infraspinatus & Teres minor ; main action (humerus external rotation), Example (twist your arms with your knuckles facing backward)

-Subscapularis ; main action (humerus internal rotation), Example (twist your arms with your knuckles facing forward.

Muscles that move the humerus bone (but are not attached to the scapula

-Pectoralis Major ; Main action (abduction of humerus in flexed position, Example (start with your arms straight out in front & bring your palms together)

-Latissimus  ; Main action (adducting humerus to side body , Example (with your arms out in a T shape lower them to your side

-Lateral Deltoid ; Main action (adduction of humerus [with supraspinatus]), Example (with your arms at your sides,raise them to T shape)

-Anterior Deltoid ; Main action (Flexion of humerus) , Example (with your arm by your sides raise them up in front of you

-Posterior Deltoid ; Main action (extension of humerus) , Example (with your arms by your sides bring them behind you)

Muscles that move the scapula

-Pectoralis ; Main action (interior and inferior tipping of scapula[if the ribs not moving]) Example (tilting the top of the shoulder forward and down)

-Serratus Anterior ; Main action (protraction of scapula), Example (forward rounding of the shoulders)

-Levator Scapula & upper trapezius ; Main action (elevaton of scapula),Example (lifting the shoulder to ears)

-Rhomboid & Mid trapezius ; Main action (retraction of scapula), Example (drowning the shoulder blades toward each other)

-Lower Trapezius ; Main action (depression of scapula), Example (pressing your shoulde

Common habitual patterns and shoulder misalignments

Due to the fact that most of modern-day society lives in the flexion portion of the (think driving, sitting, typing etc) we can experience a lot of imbalance between pairs of muscles eventually leading to misalignments in the body. The muscles on the front body become “tight” as in limited in their range of motion.

Working on computers for too long without breaks can lead to tight, locked-short pectorals and serratus anterior muscles, which then leads to tight, locked-long rhomboids, mid and lower trapezius muscles on the back. The accumulated years of typing can eventually lead to tight, locked-short internal rotators (subscapularis) and tight, locked-long external rotators (infraspinatus).

Hunching up our shoulder because of stress and/or cold weather can lead to tight, locked-short upper trapezius and tight, locked-long lower trapezius.

Added to this, unless we take up activities like climbing or rowing we have far fewer pulling than pushing actions in our daily lives. This can also lead to weak rhomboids and latissimus dorsi muscles.

All of these habitual patterns can eventually lead to imbalance and instability in the body, putting yogis at a higher potential risk of injury if they are not acknowledged and worked with. This is especially so when practicing repetitive weight-bearing poses, such as Chaturanga dandasana(Four-limb Staff pose, (Side Plank), Bakasana(Crow pose) and (Handstand).

Applying this knowledge to chaturanga dandasana

Shoulder joint integration : 4 key muscle for  chaturanga dandasana ;

The four main muscles are:

• Latissimus dorsi draws the humerus in so that the head of the humerus can be in line with the distal end (the elbow joint),
• Infraspinatus externally rotates the head of the humerus in the joint socket (plugging it in),
• Serratus anterior protracts the scapula wide onto ribcage, and;
• Lower trapezius depresses the scapula (taking the shoulders away from the ears). This dance between these four muscles is a complicated, yet so rewarding one when done with awareness and executed deliberately with the aide of the breathe.

What is Rhomboid in chaturanga dandasana?

I hear my yoga teachers teach students to engage the rhomboids when performing Chaturanga Dandasana, but rhomboids are adductors/retractors of the scapula and encourage the experience of “backbending” in the thoracic spine People are literally dumping into their chests in Chaturanga (with elbows winged far out) and shredding their shoulder connective tissue in the process.

Engaging the muscle fibres of the rhomboids, along with mid-trapezius, does effectively help to stretch the pectoralis major muscles. And in backbends the rhomboids are perfect agonists to stretch the antagonists of the pectorals. In Chaturanga Dandasana though, we don’t want to be backbending while hovering parallel to the floor as the chest will dip below the head of the humerus or the ribs come below the parallel upper arm. This puts too much pressure on the sternoclavicular and the acromioclavicular ligaments.

Instead, it is best to focus on stretching/releasing the tight pectoralis minor by actively engaging the lower trapezius muscle fibres. These draw the scapula down the back towards the hips – helping to free the clavicle area of unnecessary and possibly injurious tension and compression.

 So the full version of the cue would be “activate and engage the latissimus dorsi to bring the elbow in line with the head of the humerus!” and then follow with “plug upper arms into their socket with infraspinatus, draw shoulders away from ears with lower trapezius, and broaden shoulder blades across back with serratus anterior muscles”.