Pec Minor: The Hidden Culprit of Rotator Cuff Injuries

Published by Shauna Burchett, OTR/L on

Table of Contents

The Components of the Shoulder Joint
The Muscles in the Shoulder and Their Roles
Why the Pec Minor Can Contribute to Rotator Cuff Injuries
What To Do if You Suspect a Rotator Cuff Injury

Have you been living with shoulder pain hoping it will just go away? The good news is that when caught early, shoulder pain can often be completely resolved! Left untreated, it may worsen and eventually lead to tendonitis, bursitis, or even a tear of the rotator cuff tendons, a painful and debilitating problem that can limit your ability to raise your arm, and may even result in the need for a major surgery to repair it. However, in many cases early skilled therapeutic intervention can prevent this. There’s one rather hidden muscle that has a key role in the health of your shoulders, the pectoralis minor. It influences how your shoulders look and function.

The Components of the Shoulder Joint

The shoulder is not just one joint, but is a complex motion system made up of four joints and many muscles, seventeen of which are attached to the shoulder blade and several that come from the rib cage. One of these, the pectoralis minor, is a small fan-shaped muscle that arises from the front of the upper ribs and attaches to the scapula on a small finger-like projection, called the coracoid process. You can feel that just under your collarbone (clavicle) out towards the shoulder.

The Muscles in the Shoulder and Their Roles

Although this muscle is small, it can exert a powerful influence on your shoulder. Your rotator cuff muscles are also rather small and very influential for normal shoulder function. The rotator cuff is composed of these four muscles; the infraspinatus, supraspinatus, teres minor and subscapularis. They all arise from the scapula and attach to the upper arm (humerus). The main function of the rotator cuff is to help stabilize, rotate and control the motion of the upper arm as you raise your arm overhead. These four muscles produce small but important motions that control the position of the arm as it elevates, and the supraspinatus has the critical job of pressing the head of the humerus into its “socket”, the glenoid labrum, thus keeping it from being compressed under the acromion process. The supraspinatus is the main culprit in 90% of all rotator cuff injuries, and this is due in part to its location. The tendon of the supraspinatus comes off the shoulder blade in a relatively straight angle (somewhat like drawing a line through your body from shoulder to shoulder), and travels beneath a bony prominence of the scapula called the acromion process, then attaches to the top of the upper arm.

Why the Pec Minor Can Contribute to Rotator Cuff Injuries

Here’s where the pec minor becomes the hidden culprit in rotator cuff injuries. When the pec minor is held in a shortened position, or when it is overused, it will pull the scapula forward, holding the upper arm in an abnormally internally rotated position, placing tension on the supraspinatus tendon. This predisposes it to injury, because as you raise your arm above your shoulder, the tendon can become pinched/compressed under the acromion process. With repetition the tendon may become swollen, inflamed, painful, and thinned, causing tendonitis. This is known as impingement syndrome. Impingement syndrome is accompanied by pain and difficulty when raising the arm or performing reaching activities. If left untreated, it can progress to a partial tear or even a complete rupture of the tendon off the bone. Again, when taken care of early, this process can be fully reversed, preventing serious harm to your shoulder. If you’re currently experiencing shoulder pain, here are some self help tips.

What To Do if You Suspect a Rotator Cuff Injury

First of all, rest the arm by avoiding activities that cause or worsen the pain. The “no pain, no gain” adage does not apply in this case, and in fact, rarely ever does. Next, if you have pain in the shoulder while you try to sleep, when lying on your back, try placing a thick pillow under the back of the upper arm, positioning it about 30 degrees away from your side. Pull up the remaining length of the pillow between your arm and your rib cage and allow your forearm to rest on it. This can also be done if lying on your non-painful side.

Next, try to use good posture as much of the time as you can. Hold your shoulders back a bit and avoid a slouched position of your back, which leads to the rounding forwards of your shoulders. When working at the computer or doing other tasks in which you might be predisposed to slouch, take short breaks and do these exercises:

Pectoralis Minor Doorway Stretch. Start by standing in front of a doorway. Place the forearm of your painful shoulder on the side of the doorway with your arm angled about sixty degrees away from your side. You should not yet feel a stretch. Place one foot forwards, slowly and gently shifting your body forwards a small distance and stop. Now you should be feeling a slight stretch in the front of your chest. Don’t twist your torso but keep your shoulders straight across and in line with each other. Make sure to maintain only a gentle stretch and do not shrug your shoulders during the exercise. Hold this position for thirty seconds. Take the pressure off and repeat three to five times. Repeat twice a day.

Scapular Retraction: In addition to stretching the pectoralis minor, it’s helpful to strengthen the muscles between your shoulder blades. Start by sitting or standing upright and gently squeezing your shoulder blades together. Hold this tension for five to ten seconds, relax, and then repeat. Do one to two sets of eight to ten repetitions. Repeat twice a day.

Neither of these exercises should cause pain or worsen the pain, and if they do, then discontinue them. The most effective way to find the “hidden culprit” and resolve your shoulder pain is to schedule an appointment with a physical or occupational therapist who will perform an assessment and develop an individualized treatment plan to put you on the road to recovery. If the pain is lingering, even if it’s not severe but is limiting your ability to use your arm, don’t wait to seek help. The experienced therapists at Synergy are here to help you find the relief you need. If you have questions or would like to schedule an appointment, contact Synergy Healthcare in Spokane Valley by using the buttons below. Alternately, give our front desk a call at 509-413-1630.

Synergy Healthcare offers physical therapy, occupational therapy and massage therapy in Spokane Valley, WA. Our highly trained therapists are ready to get you back on track fast! We try to prepare helpful articles that can help enrich your life. Have a question you want answered? Email us at info@synergyspokane.com or call at 509-413-1630 for more information. Comment below or give us a shout-out on Facebook – we love to hear whats on your mind!


Shauna Burchett, OTR/L

Shauna Burchett, OTR/L is a skilled occupational therapist and the owner of Synergy Healthcare. She graduated from the University of Alberta in 1993 with a degree in Occupational Therapy. Shauna began her career as an occupational therapist specializing in traumatic head injuries. She has also worked in skilled nursing facilities specializing in long and short term geriatric rehabilitation. Shauna has been in private practice since 1998.