“. . . according to the Yoga Sutra (3.1), the term [Bandha] refers to the ‘binding’ of consciousness to a particular object or locus (desha), which is the very essence of concentration.”
Georg Feuerstein



Saturday, March 19, 2016

Shoulder Biomechanics, Part III: The Supraspinatus Muscle

Hello Friends,

Let’s cap off the muscles of your rotator cuff with the supraspinatus. This muscle originates in a trough-like area above the scapular spine, hence its name supra, which means “above”. The supraspinatus then inserts onto the greater tuberosity just behind where the long head of the biceps enters the shoulder (figure 1).

(We’ve covered the subscapularis, infraspinatus and teres minor muscles along with some key biomechanical points about each muscle—click to review.)




Figure 1: The supraspinatus muscle of the rotator cuff (with the infraspinatus and teres minor faded).


Contracting the supraspinatus abducts the humerus at the glenoid socket (takes the arm out to the side) for the first 15 degrees. After that, it becomes a synergist of the deltoid for abduction. As with the other muscles of the cuff, the supraspinatus also stabilizes the humeral head in the socket. Figure 2 illustrates this in Warrior II. 


Figure 2: The supraspinatus contracting to synergize the deltoid in abducting the shoulders in Warrior II.


The supraspinatus is the rotator cuff muscle that is most frequently torn. Tears start to become common beyond the age of forty, with an increased incidence in each decade of life. Figure 3 illustrates a supraspinatus rotator cuff tear.



Figure 3: Full thickness tear of the supraspinatus muscle (with the long head of the biceps shown in front of the supraspinatus).


Drawing your arm across the chest (adducting it) stretches the supraspinatus, as well as the capsule of the shoulder and the deltoid muscle. Figure 4 illustrates this action in Garudasana. Note the muscles (colored blue) that contract to stretch the supraspinatus and the muscles that also stretch in this pose (colored red). 


Figure 4: The supraspinatus muscle stretching in Garudasana. The muscles in red are stretching and those in blue are contracting.


Click here to take the rotator cuff quiz to test your knowledge!

Thanks for stopping by. Stay tuned for the next post when I'll go over the interaction between the deltoid muscle and the rotator cuff. By the end of this four-post series, you'll have a good understanding of the functional anatomy and biomechanics of the shoulder joint as applied to yoga. Click here to browse through the Bandha Yoga book series on anatomy, biomechanics and physiology for yoga.


All the Best,


Ray Long, MD

Sunday, March 13, 2016

Shoulder Biomechanics, Part II: The Infraspinatus & Teres Minor Muscles


Hello Friends,

Welcome to the second of the four-part series on the shoulder joint. Last week I discussed the subscapularis muscle, which is the main shoulder internal rotator. Now we’re on to the antagonist muscles of the subscap, namely, the infraspinatus and teres minor. The infraspinatus arises in a trough below the scapular spine, hence its name (“infra” means below). The teres minor arises back part (dorsum) of the scapula along its outer (lateral) border. The infraspinatus and teres minor insert onto the back part of the greater tuberosity of the humerus, as shown in Figure 1. 

These muscles externally rotate the humerus, with the infraspinatus being the strongest external rotator of the joint. The infraspinatus and teres minor also function to stabilize the humeral head in the socket (glenoid).




Figure 1: The infraspinatus and teres minor muscles of the rotator cuff (the supraspinatus is the faded muscle on top).


The Force Couple

These muscles combine with the subscapularis at the front of the joint to form a “force couple”. In this manner, antagonist muscles (for rotation) become synergists (for stability). Therapy (and surgery) for rotator cuff pathology is directed towards restoring this force couple. Click here to read about concept of antagonist/ synergist combinations for the hip muscles in yoga. Click here for some cues to use this in Dandasana.
Figure 2 illustrates this biomechanical process. This view is looking down on the shoulder with the front of the joint towards the bottom of the page



Figure 2: The force couple between the infraspinatus and subscapularis muscles. This view is looking down on the shoulder with the front of the joint towards the bottom of the page.

Poses with the arms in reverse Namaste' stretch the infraspinatus and teres minor, as does Gomukhasana. Those of you who are more flexible may gently press the knife edge of the hand into the back to "load" the external rotators. Folks who are tighter may simply grasp the elbows or hands behind the back. Click here for more details and an animation of Gomukhasana stretching these muscles as well as a not so obvious cue for loading and using PNF for this stretch.

Figure 3: Stretching the infraspinatus and teres minor by internally rotating the shoulders in Parsvottanasana.


Externally rotating the shoulders in poses like Trikonasana (Triangle) can be used to activate the infraspinatus and teres minor. Figure 4 illustrates this, as well as the myofascial connection between these muscles and the muscles that retract the scapula, namely the trapezius and rhomboids.




Click here to take the rotator cuff quiz and test your knowledge!

Thanks for stopping by--I hope you're enjoying learning about biomechanical concepts like the force couple. Stay tuned for the next post when I'll go over the last muscle of the rotator cuff, the supraspinatus. Then I'll finish up with the relationship between the rotator cuff and the deltoids. By the end of this four-post series, you'll have a good understanding of the functional anatomy and biomechanics of the shoulder joint as applied to yoga. Click here to browse through the Bandha Yoga book series on anatomy, biomechanics and physiology for yoga.


All the Best,

Ray Long, MD

Sunday, March 6, 2016

Shoulder Biomechanics, Part I: The Subscapularis Muscle

Hello Friends,

This is the first of a four-part series on the shoulder joint, focusing specifically on the rotator cuff and its biomechanical relationship with the deltoid muscle. Let's begin by looking at the muscles that comprise the rotator cuff, starting with the subscapularis. As figure 1 illustrates, the subscapularis occupies the space, or fossa, at the front of the scapula. From there it attaches to the lesser tuberosity, a knob-like structure on the humerus bone at the front of the shoulder. Concentrically contracting the subscapularis muscle (shortening the muscle on contraction) internally rotates the shoulder. The subscap also acts, in conjunction with the infraspinatus muscle, as a stabilizer of the humeral head in the socket (glenoid). We test strength and function of this muscle with the "belly press" test or the "bear hug" test. Tightness in the subscapularis can limit external rotation of the shoulder.


Figure 1: The subscapularis muscle, illustrating the origin on the inside of the scapula and the insertion on the lesser tuberosity of the humerus.


Figure 2 illustrates one of the poses that stretch the subscapularis muscle, namely, Gomukhasana. The upper side humerus externally rotates in this pose, thus stretching the muscle as shown.

Figure 2: This illustrates the effect on the subscapularis muscle of the upper arm in Gomukhasana. External rotation of the humerus stretches the muscle.


Figure 3 illustrates engaging the subscapularis muscle in Ardha Baddha Padma paschimottanasana. Advanced practitioners can attempt to lift the hand off the back to engage the muscle in this pose. This also replicates the "lift off" test, which is used in orthopedics to test the function of the subscap muscle.

Figure 3: This image illustrates contraction of the subscapularis muscle to internally rotate the humerus.



Finally, we have the subscapularis as a stabilizer during a static position in a pose. In Warrior II, attempt to internally rotate the shoulders by imagining pressing the mound at the base of the index fingers down against an object. Resist this by externally rotating the shoulders at the same time. Co-contracting opposing muscles--like the subscap and infraspinatus--stabilizes the head of the humerus in the socket while the deltoid contracts to abduct the humerus. Click here to go into a bit more depth on the subject of stabilizing your shoulders in your Downward dog pose. 


Figure 4: Co-contracting the subscapularis and the infraspinatus stabilizes the humeral head in the socket while the deltoid muscle abducts the humerus.



Click here to take the rotator cuff quiz and test your knowledge!

Thanks for stopping by. Stay tuned for the next post when I'll go over the antagonist muscle for the subscapularis. By the end of this four-post series, you'll have a good understanding of the functional anatomy and biomechanics of the shoulder joint as applied to yoga. Click here to browse through the Bandha Yoga book series on anatomy, biomechanics and physiology for yoga.

All the Best!

Ray Long, MD