The Breath of Life (part 2)

The Anatomy of the Breath

In Part 2 of this series (find Part 1 here) we are diving into some specific information about how breathing works, and about the structures in the body which support it. Fear not, I have kept things simple and short! Read this one carefully, as you will need a basic understanding of the information here as we go on to explore common ways in which we interfere with the breath in Part 3.


The Diaphragm

The diaphragm is the main muscle of respiration. It attaches to the lower edge of the rib cage and is shaped like a dome.  

When we breathe in, the diaphragm contracts and flattens. This increases the space in the chest cavity, causing the lungs to expand along with it. So long as there is a clear passage from the nose or mouth then air will flow in through the trachea to fill the lungs. Note that because atmospheric air is under pressure we don’t have to effortfully draw it in: it will come in naturally as the space for it increases.

When we breathe out, the diaphragm relaxes and returns to its former shape (with the help of some other structures that we’ll come to later) and the used air, now depleted of oxygen, flows out of the lungs again through the mouth or nose.

Note that we should never try to influence the diaphragm directly, it is not a muscle over which we have conscious control.

The Rib Cage

The word cage in rib cage is a bit misleading. It can easily be taken to imply a fixed and immobile enclosure when in fact it is a flexible structure. This flexibility enables a greater expansion of the space in the chest cavity (and hence of the lungs) than the diaphragm working on its own can produce. 

Let’s have a look at the structure in more detail...

At the front of the chest the ribs are joined to the breastbone with flexible cartilage. At the back they attach to the vertebrae of the spine with joints, which allow them to rotate up and down.  

Because of this flexibility, when the inter-costal muscles (which connect each rib to the next) contract, it causes the ribs to rise like bucket handles, thus further increasing the expansion of the lungs as we breathe in.  


In normal breathing the elasticity of the rib cage means that little or no effort is needed on the out breath to return the rib cage to its former position and empty the lungs. Breathing out is essentially a letting go.

The diaphragm and ribs work together to allow us to utilise the full range of our lung capacity. But in order for that mechanism to work properly it needs to be supported from below....

The Pelvic Floor and Muscles of the Abdomen

We’ve seen how the diaphragm contracts and descends when we breathe in. However the space into which it wants to descend is not empty! It’s full of the gut, liver, kidneys and other organs of the abdomen. 

These internal organs are not very compressible, so they need to be able to move down with the diaphragm to enable it to descend. They can do this because they are contained in an elastic muscular ‘basket’ made up the big sheets of muscles which wrap around the front and sides of the abdomen, and the pelvic floor.

pelvic floor.jpg

This muscular container gently lets go as we breathe in, allowing the contents of the abdomen to be displaced by the descending diaphragm and helping to regulate its movement. The muscles then offer support to the releasing diaphragm as we breathe out again. This support may either be very subtle and delicate (as it should be in normal breathing) or more forceful when we need to blow out under pressure (for example playing a wind instrument).  

This process is why your belly moves in and out as you breathe. It not only allows the descent of the diaphragm but, just as importantly, supports and helps to regulate the structures above — and consequently the whole breathing process. The pelvic floor and the diaphragm have a particularly intimate relationship. They are connected at a fundamental neurological level. When one contracts the other releases, and vice versa. This means that unnecessary tension in the pelvic floor will always have a knock on effect on the diaphragm and limit and constrict the whole breathing mechanism.

It’s important to note that when all is working as it should the activities described above are automatic. Generally we don’t need to be controlling them, we just need to allow them to function as nature intended. However we often get into (usually unconscious) habits of interfering with the breath. This is when things can go wrong, and it can cause problems with posture, energy, tension, and emotional expression.

In the next part of this series we will be looking at what happens higher up in the throat and head to regulate the airflow and allow it to be used for vocalising and to support our structure.

<<Part 1                Part 3>>