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  • Writer's pictureNashville PT

Muscle Monday: Subscapularis

The subscapularis muscle is one of the 4 muscles that makes up the infamous rotator cuff in the shoulder. It is the largest and strongest of the 4 rotator cuff muscles, and is a very important stabilizer for the front of the shoulder (glenohumeral) joint. For those of you with a “loose shoulder” or one that has previously been dislocated, this muscle is SUPER important to keep strong to improve overall joint stability.

The rotator cuff is a group of 4 muscles that do very important work deep in your shoulder. They live deep to your deltoid, so you don’t see these guys when you flex in the mirror and therefore, they often get skipped when working out in the gym. But don’t let that be the case with you, because without good strength of the rotator cuff muscles, you won’t be able to work out those showy muscles (like the deltoid) without developing pain in the process!

The subscapularis performs several important functions in the shoulder. As mentioned previously, it is important for providing stability across the front of the shoulder joint. When it contracts, it internally rotates the humerus which is necessary for activities like reaching behind your back to tuck in your shirt or fasten a bra, and especially when performing overhead throwing activities or other overhead sports. Another important function of the subscapularis is its ability to depress (pull downward) the head of the humerus when it contracts. Depression of the humeral head is really important to prevent a painful condition known as impingement syndrome, which is when the head of the humerus elevates too much when raising your arm overhead and “pinches” structures between the head of the humerus and the acromial process above it. Ouch!

The subscapularis can be injured gradually by repetitive, overhead motions (like throwing activities) in which tendonitis begins to develop, which can ultimately lead to further degeneration of the tendon of the subscapularis and eventually lead to a tear. Another way this muscle can be torn is when the shoulder is forced into external rotation, which often happens when a shoulder dislocates, or when there is trauma such as a fall on an outstretched arm.

What’s the point of knowing all of this??

Since the subscapularis is such an important stabilizer of the shoulder, and important for preventing impingement syndrome, which can lead to degenerative tears in the rotator cuff musculature, it is really important that this muscle stay strong, but also well-balanced with regard to the other muscles of the shoulder, including the other rotator cuff muscles - namely the infraspinatus and teres minor muscles. The infraspinatus and teres minor muscles do the opposite motion as the subscapularis – they are external rotators of the shoulder. Therefore, if they are not well-balanced with the subscapularis muscle that does internal rotation, it can cause the humeral head to glide and shear anteriorly and superiorly (to the front and upward), leading to impingement syndrome. If any of the rotator cuff muscles become irritated due to being impinged, they will become inflamed (tendonitis) and with time, this can become chronic in nature and lead to a degenerative tear. Depending on the extent of the tear or degeneration of the tissue, surgery may be your only choice to fix it. This is why we recommend a Total Body Wellness Assessment prior to starting a new gym program because underlying weakness of these muscles can be identified and addressed before they become an issue from lifting too much weight overhead or participating in your throwing sports or other overhead sporting activities.

What type of person do we typically see having problems with this muscle?

o Those to participate in overhead sporting activities!

o Baseball players

o Swimmers

o Tennis players

Here are some other facts about the subscapularis:

- It originates on the inside or anterior surface of the scapula (shoulder blade), in an area known as the subscapular fossa. It then attaches to the humerus where it inserts on the lesser tubercule of the humerus.

- It is innervated by the upper and lower subscapular nerves.

- Its function (along with the other rotator cuff muscles) is to help control the ball and socket joint of the shoulder by helping to keep the head of the humerus (the ball) centered within the glenoid fossa of the scapula (the socket). Its other function is to internally rotate the shoulder and provide stabilization to the front of the shoulder joint.

- Pain from this muscle is often felt on the front of the shoulder but trigger points within the muscle belly can refer pain into the shoulder blade region and down the back of the arm.

Moral of the subscapularis story: Don’t neglect this muscle at the gym! And if you develop shoulder pain with your workouts or sporting activities, don’t wait until it’s too late to see a PT!

Early signs of shoulder pain are easy to address and correct with physical therapy intervention, and often resolve very quickly. When you wait until your shoulder pain is severe, many times it will require taking some time away from the activities you love and ultimately can lead to a degenerative process or even a tear. If you want to be ahead of the game and avoid shoulder pain altogether (and improve your sport performance), contact us for a Total Body Wellness Assessment so we can identify any issues that might lead to injury of this muscle (or any other muscle that works in conjunction with it) in the future.

If you feel you've been having trouble with your subscapularis (or shoulder or rotator cuff) and want an expert to take a look, we'd love to help you! You can reach us by call/text 615-428-9213 or email to set up an appointment with a PT today! You can also book online here

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