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Physio-Matters

The muscles of the rotator cuff

The rotator cuff is composed of 4 muscles of the shoulder. Each muscle connects from the scapula (shoulder blade) to the greater and lesser tubercle (rounded prominences of bone where muscles attach) of the humerus (upper arm bone), forming a "cuff".

The function of the rotator cuff is to allow for motion of the shoulder joint and to provide stability. The four muscles of the rotator cuff are outlined below, including where each muscle originates and then attaches, the movement each produces, and the nerves that supply (innervate) each muscle:

 

Supraspinatus Muscle

This muscle originates on the supraspinous fossa (small groove) of the scapula and attaches to the superior (top) and middle facets (small, smooth area of bone) of the greater tubercle of the humerus. Its function is to abduct the arm (raises the arm out to the side). It is innervated by the suprascapular nerve.

 

 

 

Infraspinatus Muscle

This muscle originates on the infraspinous fossa of the scapula and attaches to the posterior (back) facet of the greater tubercle of the humerus. Its function is to externally rotate the arm. It is innervated by the suprascapular nerve.

 

 

 

 

Teres Minor Muscle

This muscle originates on the middle half of the lateral (outside) border of the scapula and the attaches to the inferior (below) facet of the greater tubercle of the humerus. This muscle also externally rotates the arm. It is innervated by the axillary nerve.

 

 

 

Subscapularis Muscle

This muscle originates on the subscapular fossa of the scapula and attaches to the lesser tubercle of the humerus. Its function is to internally rotate the arm and it is innervated by the upper and lower subscapular nerve.

 

These four muscles can be remember by the acronym "SITS".

This article is written by or on behalf of an outsourced columnist and does not necessarily reflect the views of Castanet.



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About the Author

Kristi Scott, B.Sc., M.Sc.P.T., CAFCI

Kristi is a Registered Physiotherapist. She joined her mother, Shirley Andrusiak, at Guisachan Physiotherapy after graduating from the Masters of Science in Physical Therapy Program at the University of Alberta in 2010. She also holds an Undergraduate Bachelor of Science Degree from the University of Victoria. Since graduating Kristi has completed numerous continuing education courses including manual therapy, vertigo, sport first responder, and golf related rehabilitation.  She has also completed her training with the Acupuncture Foundation of Canada Institute, and is certified to perform acupuncture, holding a designation of CAFCI.

Kristi brings an energetic, exercise based approach to her practice. She focuses on client centered care, education, exercise prescription, and manual therapy techniques. 

You can contact Kristi by email at [email protected]

 

 

 



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