External and Internal Intercostals: Learn Your Muscles

It’s possible that you didn’t know there were muscles between each of your ribs. The thought had never crossed my mind until I started studying anatomy. Because of a lack of awareness, the external and internal intercostals are frequently underused. When the intercostals don’t work, your rib cage becomes somewhat stationary instead of being the dynamic bony structure that it’s intended to be.



Thanks to The Wellness Digest for this image.

The intercostal space is the space between each rib. It’s here, in the intercostal space, where you have the origin and insertion for both the internal and external intercostals.

The origin for the external intercostals is along the lower border of a rib. It then inserts on the upper border of the rib below. This means that these muscles run from the top to the bottom of the space between each rib. The muscle is at a slight angle, slanted toward the midline of the body. Also, as you might expect, the external intercostals are on the outside of the rib cage.

The internal intercostals move the opposite way. They originate on the upper border of the bottom rib and insert on the lower border of the rib above it. The muscle fibers run from bottom rib to top rib on a slight diagonal toward the midline of the body. These muscles are located behind the external intercostals, so they are deeper within the body.


You may not realize this, but your rib cage is supposed to be a three-dimensional moving structure. As you inhale, your rib cage is supposed to expand to the front, back, and each side. Then, when you exhale, your whole rib cage should contract. Unfortunately, no one ever teaches you how to breathe, so these muscles frequently get lost and ignored.

If this is the case, your intercostals simply work to stabilize your rib cage and keep the correct space between your ribs. There’s nothing wrong with using your intercostals in this capacity, but you are missing out on a great opportunity if you’re not using your intercostals to help you breathe three-dimensionally. Here’s a link to an article on Pilates breathing that provides more information about breathing into all sides of your rib cage.

Common Dysfunction

When the external and internal intercostals are dysfunctional, your rib cage does not expand as much during respiration. An additional side effect can be kyphosis, which is the rounding of the upper back. Truth be told, these are both really minor issues that can easily be remedied with exercise.

However, if you experience some trauma like a displaced broken rib or a knife injury, your muscle dysfunction may be different. As mentioned earlier, the external and internal intercostals do serve as a sort of place holder for the ribs. Without those muscles working properly and with a significant injury, it would be possible for some of the ribs to shift.

Restoring or Maintaining Health

If you think you have injured your intercostals, please visit your doctor. Your doctor can order the appropriate imaging, therapy, and medicine to help you heal.

However, if you believe your intercostals are just fine and you’re looking for exercises to strengthen them and help keep the muscles healthy, here’s a suggestion:  practice mindful breathing. As you inhale, feel your rib cage expand in all directions. Feel it contract as you exhale. You can use pursed lips as in Pilates breathing or you can keep your mouth closed like in ujjayi breathing. Also, try practicing other styles of breathing such as:  nadi shodhana, kumbhaka, viloma, chandra bhedana, surya bhedana, bhastrika, kapalabhati, shitali, or bhramari.

More Information

I consulted [easyazon_link identifier=”1623170206″ locale=”US” tag=”custpilandyog-20″]The Concise Book of Muscles[/easyazon_link] 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 [easyazon_link identifier=”1878576003″ locale=”US” tag=”custpilandyog-20″]Flash Anatomy Muscles Flash Cards[/easyazon_link]. Any time a client comes to me with pain, I use these flash cards.

What’s another great way to strengthen your external and internal intercostals? Let us know in the comments below.

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About Sarah Stockett

Hi, I'm Sarah! I'm a certified Pilates and yoga instructor with a passion for pain relief. I believe you can use simple exercises to relieve your aches + pains. AND, I believe I can teach you how.