The role of the Pec minor Muscle and Shoulder pain

 In Upper Limb

What is the pectoralis minor muscle

Frequently our bodies are put in a position where they are not working with optimum efficiency (poor posture). If our bodies are not working with optimum efficiency, this will cause some structures to tighten up more than others leading to muscle imbalances. One very important muscle to consider when thinking about tight muscles and their impact on body mechanics is the pectoralis minor muscle. The pec minor muscle attaches from the corocoid process in the shoulder blade to the rib cage (3rd to 5th ribs). When this muscle is contracted, it causes protraction and depression of the shoulder blades, essentially causing the shoulders to roll forward, or ‘slouch’.

What causes the pec minor muscle to get tight?

This is very important when considering the implications of your job, particularly if you sit at a desk for long periods of time. When sitting at a desk without proper support, the force of gravity will inevitably cause us to hunch over and roll our shoulders forward, causing the pec minor muscle to rest in a shortened position. If you do this activity for long enough, it will cause the muscle to shorten which will leave you permanently in a slouched position.

Why, if these muscles aren’t sitting at their optimum length, is this important?

These changes in muscle lengths are particularly important because it can also cause and exacerbate shoulder impingement and pain. As mentioned before, if the pec minor muscle is tight, it will cause the shoulder blades to protract and the head of the humerus to internally rotate. This in turn puts a lot of stress on the muscles in the back and the top of the shoulder as they have now to work harder to counteract the pec minor muscles and are more easily injured as they are constantly fatigued (Schultd, 2007). The muscles that counteract the pec minor muscle are known as the muscle’s antagonists. The antagonists of the pec minor muscle include the Trapezius (upper and lower fibers), Serratus Anterior (lower fibres), and the muscles in the posterior cuff of the shoulder. As these muscles are now not sitting at their optimum length, they are not producing force efficiently and also become fatigued and are more prone to injury.

As a result, you increase your risk of injury when you try to perform any sort of activity that involves using your shoulder through range (for example, overhead activities). This is why, at pogo, we get a lot of clients that come in complaining of pain at the top of the shoulder from doing small things such as putting out the washing or washing their hair in the shower. Usually, these activities wouldn’t put enough strain on your body to cause injury; however, because all the shoulder muscles are fatigued from being in a less efficient position whilst working for 8-10 hours each day, they are more susceptible to injury. So even if you don’t have pain right now, but you have a job that is constantly forcing you into a slouched position; get yourself screened so you can help avoid injuries and continue to have a pain free lifestyle!

What can you do to help prevent injury or exacerbation of an injury?

So, essentially, tp prevent injury you need to increase the length of the pec minor muscle, put in preventative strategies at work (or any other activity that may force you into a hunched position) so you do not get a recurrence of shoulder dysfunction and strengthen the antagonists to improve shoulder stability. Self-directed stretching has been shown to be quite effective in improving pec minor muscle length (Borstad & Ludewig, 2005). While at work, we need to put some systems in place to ensure minimal slouching, because slouching is big contributor to shoulder pain (Lewis, 2005). An Obusforme back support or even standing desks are two ideas to help prevent slouching whilst sitting for long periods of time at the work station. Finally, once your body is in a more biomechanically sound position, enrolling in a good strengthening program to increase the muscle’s postural endurance is essential.

Alister Cran
POGO Physio Associate Physiotherapist


Borstad, J.D. & Ludewig, P.M. 2005. Comparison of three stretches for the pectoralis minor muscle. Journal of Shoulder and Elbow Surgery. 15 (3): 324-330

Schultd, K., Ekholm, J., Harms-Ringdahl, K., Nemeth, G. & Arborelius, U. 2007. Effects of changes in sitting work posture on static neck and shoulder muscle activity

.Ergonomics. 29 (12): 1525-1537

Lewis, J.S., Wright, C., Green, A. 2005. Subacromial Impingement Syndrome: The Effect of Changing Posture on Shoulder Range of Movement. : Journal of Orthopaedic & Sports Physical Therapy. 35(5): 72-87

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