Many years ago, we got a Wii for Christmas. Immediately, we began our tournament of sports: bowling, golf, baseball, and finally boxing. Really, everyone was doing very well physically (no aches and pains) until we started Wii boxing. In the heat of the moment, we felt fine. The day after Christmas, we all woke up barely able to move our arms.
Each of us had a killer pain coming from what seemed to be the armpit area. This limited our abilities to do things like get a box of crackers off a shelf or brush our teeth. In our jab and hook enthusiasm, we injured our serratus anteriors. That’s how I learned the hard way about “the boxer’s muscle.”
The origin of the serratus anterior is on the outer surface of the upper 8 or 9 ribs and the fascia covering the intercostals at the side of the chest. According to the Flash Anatomy Flash Cards, it inserts on the “costal surface of the vertebral border along the inferior angle of scapula.” This means that it inserts along the outside edge of your scapula.
To easily find your serratus anterior, raise your arm. Put your hand at the bottom of your armpit and slide it down the outside of your rib cage until you’re about two-thirds of the way down. For women, you will hit your bra line. Now, slide your hand up toward the outside edge of your shoulder blade. That’s your serratus anterior.
Because of this insertion, the serratus anterior helps hold the scapula on the back of the rib cage. It is also responsible for a scapular action called protraction. When the scapula slides forward, almost as if it’s trying to slide off the back of the rib cage, that’s protraction. Additionally, the serratus anterior rotates the scapula upward.
The main function of the serratus anterior is to push or reach something far away. Because of the scapula’s ability to move and add some extra length to your arm, the serratus has been called “the boxer’s muscle.” This is because the serratus is crucial to throwing a good punch.
When the serratus anterior is dysfunctional, winging of the scapula can occur, especially when holding a weight in front of the body. To find out if your scapula wings, find a friend or a large mirror. Make sure you can observe your shoulder blade. With a straight arm, hold a weight in front of your chest. (The weight should be slightly challenging but not so heavy that your shoulder muscles bail while you’re trying to observe yourself.)
With your arm in front of you, check out your shoulder blade. Your serratus anterior should be able to hold the whole scapula flat on the back of your rib cage. If, however, you notice the bottom outside edge of your scapula is lifting, your scapula is winging. Since the insertion of the serratus anterior is right on the outside edge of your scapula, it should be able to easily hold it in place, even with the challenge of weight. Any lift of your scapula indicates serratus anterior dysfunction.
Restoring or Maintaining Health
If you believe you have sprained, torn, or simply injured this muscle, please visit your doctor. Your doctor can order all of the appropriate imaging, therapy, and medicine to help you recover quickly.
If your issue is minor (like a winging scapula) and you want to restore health and function yourself, here are some exercises.
- Downward facing dog
- Poses where your arms reach above your head like Chair pose, Crescent lunge, Warrior 1, and Warrior 3
- Arm balances like Handstand and Crow pose
- The various modifications for Swimming, including Sunbird
- Arm circles, Arm scissors, and other arm reaches that depend on scapular stability
Basically, if your arms reach above your head, this will be a good exercise for the serratus anterior.
I consulted The Concise Book of Muscles by Chris Jarmey. Recently, the book was revised and is in its third edition. I love this book as a quick go-to guide for easy to understand anatomy.
For those who are more interested in technical terminology and smaller muscles, I recommend Flash Anatomy Muscles Flash Cards. Any time a client comes to me with pain, I use these flash cards.
What’s your favorite way to strengthen your serratus anterior? Let us know in the comments below.
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