Have you ever felt a pain deep in your armpit that hurt when you were benching or moving your shoulder a certain way? If so, that's most likely your subscapularis muscle. The subscapularis muscle is one of the four muscles of the rotator cuff. The subscapularis is the only muscle of the rotator cuff to internally rotate the shoulder (the rest externally rotate the shoulder). This is not the most common injury, nor is the most commonly affected aspect of the rotator cuff, but it is an injury that can sideline you for a bit longer than you'd want. Let's dive deeper into more about the subscap, how it becomes affected, and how to manage your pain and injuries.
This muscle is located in front of the scapula and attaches to the lesser tubercle of the humerus, resulting in internal rotation when activated. To understand this further, the rest of the rotator cuff muscles (supraspinatus, teres minor, and infraspinatus) are located on the back of the scapula and attach to the greater tubercle, resulting in external rotation when activated. Along with the pectoralis major, teres major, and latissimus dorsi, the subscapularis internally rotates the shoulder. Think of bringing your arm closer to your midline like you are arm wrestling or when bringing your arm forward when throwing.
The most common injuries of the subscapularis are musculotendinous strains, tendinopathy, or full tears. Full-tears are the worst-case scenario. Those are almost always surgical consultations resulting in surgery and can take several months to rehabilitate. Common causes of this include excessive external rotation stretch and excessive and rapid stress applied to the muscle. Throwing is a very common cause of this as the positioning results in great stretch and rapid force production. In addition, chest pressing can result in excessive strain on the subscap. This occurs due to lack of external rotation forcing more stress on the muscle in the bottom position of the chest press or when attempting to rapidly produce force from the bottom position of the chest press.
When injury occurs, there is usually a "pop" sensation, deep in the armpit and it feels hard to reach. Movements like washing your hair and scratching your back become quite difficult and painful. The main test to determine if it is strained or completely torn is to put your hand behind your back and lift it off your back. If you are unable, that means you probably have a full tear and will need an MRI. If you can, but it hurts, that is where people like us come in.
Following proper diagnosis, treatments of a subscapularis strain include manual therapy to the affected area, dry needling, and potentially shockwave. Becuase it is a difficult area to get to, it is something where there aren't that many options to be done and they are all quite uncomfortable. This is personally one of my least favorite areas to get worked on because it's both uncomfortable and somewhat ticklish.
The rehab of this injury includes building pain-free strength of the internal rotators of the shoulder and increasing external rotation of the shoulder through manual therapy and recommended stretches. This will allow for better ROM of the shoulder and reduce the risk of re-injury of the shoulder. There are some self-myofascial release methods using a PVC pipe or broomstick, but when performing, PLEASE PLEASE PLEASE do not stick it directly into the armpit! The axillary artery and a lot of nerves are housed there and it is imperative to place the PVC in the correct spot to not hurt yourself.
If you're dealing with a subscapularis injury or any shoulder injury, Strength & Spine is the office for you. We see more shoulder injuries than anything and have everything needed to help. Schedule your FREE Discovery Visit today at strengthchiro.com
-Dr. Cameron Gholampour
