Shoulder Biomechanics Part 3: The Supraspinatus Muscle

The final rotator cuff muscle in this series on shoulder biomechanics is 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 subscapularisinfraspinatus 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.

 

For more information on shoulder anatomy, visit these links:

Shoulder Anatomy 101: A Beginner’s Guide to the Shoulder Girdle

Shoulder Anatomy 102: A Beginner’s Guide to the Major Muscles of the Shoulder Girdle

Learn more about yoga and shoulder anatomy with YogaUOnline and Julie Gudmestad – Yoga Anatomy: Keeping the Rotator Cuff Healthy in Yoga.

Reprinted with permission from Daily Bandha.

Ray Long MDAuthor, Ray Long MD, FRCSC is a board-certified orthopedic surgeon and the founder of Bandha Yoga. Ray graduated from The University of Michigan Medical School with postgraduate training at Cornell University, McGill University, The University of Montreal and Florida Orthopedic Institute. He has studied hatha yoga for over twenty years, training extensively with B.K.S. Iyengar and other leading yoga masters.                 

 

Chris Macivor

3d Graphic Designer / Illustrator Chris Macivor has been involved in the field of digital content creation for well over ten years. He is a graduate of Etobicoke School of the Arts, Sheridan College and Seneca College. Chris considers himself to be equally artistic and technical in nature. As such his work has spanned many genres from film and television to video games and underwater imagery.         

 

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