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The Form and Function of the Serratus Anterior Muscle

A study to find out what each part of the serratus anterior (SA) muscle does may help therapists rehabilitate weak or injured patients. The SA starts at the shoulder blade and wraps around the side of the rib cage.

Physical therapists from five different clinics worked together to test 29 healthy adults. Electrodes were used to record electrical activity of the SA in several test positions. Each muscle test was done three times. Subjects rested 30 seconds between each set of exercises.

The researchers found that the upper part of the SA works to move the shoulder blade away from the spine. This movement is called protraction. The lower part of the SA rotates the shoulder blade upward. In this report, they describe each muscle test and what SA activity was found with each one.

Based on these findings, the researchers make a few suggestions for therapists working with patients to strengthen the SA. First, there was a lot of variability from subject to subject. No one muscle test will work for everyone.

Second, the push-up plus exercise is a good one to strengthen the SA. This is done in the push-up position with the patient protracting the shoulder blade as much as possible.

Third, the result of this study may help therapists choose the right test and design the optimal exercise program for each patient's SA muscle.

References: Richard A. Ekstrom, PT, DSc, MS, OCS, et al. Comparing the Function of the Upper and Lower Parts of the Serratus Anterior Muscle Using Surface Electromyography. In Journal of Orthopaedic & Sports Physical Therapy. May 2004. Vol. 34. No. 5. Pp. 235-243.

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