Intercostals: Essential Partners in Breathing

For some reason or another, in singing pedagogy over the recent past, we've focused a lot of attention on the diaphragm in breathing. I think we're all coming around to the truth that telling folks to "sing from their diaphragm" is an unhelpful instruction, though the idea is still present in some areas of the singing world that haven't quite learned that yet.


The truth is breathing is a dynamic and multi-faceted thing, and breathing for singing is more varied than our past pedagogy would have admitted. We can't just all breathe more deeply and expect that to solve all our breathing issues. Sometimes, that kind of directive can create more issues. If anything, modern singing pedagogy is leaning into the idea that we can breathe in all kinds of ways that work with all kinds of bodies, and get the job done. If our goal is the right tone at the right time, and with the appropriate length of phrase, etc., then however we need to breathe to get to that goal is adequate. Let's not complicate it too much. It's complicated enough!


I'll step off my diaphragmatic soapbox for a bit and shift focus now to some important muscles that can help us have more flexibility in our breathing process, the intercostals. Costals are another word for our rib bones, and so the intercostals are the muscles that are in between the ribs. Like many anatomical names, these make sense!


You may have heard in pedagogy class about the internal and external intercostals, and how they operate in expanding and contracting the rib cage during breathing. That's not all there is, but we'll start there for right now.

To inhale, the external intercostals engage and pull the ribs up and out. This creates a vacuum in the lungs that pulls air in, and we breathe in.


To exhale, the internal intercostals engage and pull the ribs in and down, and that pushes air out, allowing us to exhale. It is this exhalation that we are using when we sing, since we use that exhaled breath to interact with the vocal folds and produce sound. We won't get into the giant can of worms about how that happens right now, but I think we can all agree that it's a wonderful use of breath.


What most of us didn't learn in pedagogy texts are that in addition to these two layers of intercostal muscles, there is a third layer called the "innermost" layer. Also a totally obvious name for these muscles. They are another part of the exhalation process, because as they engage they work with the internal intercostals to bring the ribs in, but they also act to raise the rib cage.


One more group to add to our intercostal squad are the scalenes. These are also considered intercostal muscles because of how they attach to the upper ribs and pull them up during inhalation. These muscles are more active during clavicular breathing.


In the drawing to the right, you can see how the three main layers of the intercostals sit in the rib cage. Notice especially how the muscle fibers of the internals and externals criss-cross one another, and how the innermost intercostals basically orient straight up and down. The orientation of the fibers can help us to visualize how the muscles move. All three sets of muscles originate at the bottom of the rib above, and insert into the top of the rib below (read that again slowly and use the picture to help out if you need it, because that can be confusing!), and when they contract, they pull the insertion point toward the origination point. In other words, the bottom rib is pu