In the last article I talked about the anatomy which supports the function of the lungs, allowing them to expand and contract to draw in and expel air. I'm now going to say a little about what happens higher up in the body to regulate the airflow and allow it to be used for vocalising and to support our structure.
Air flows into the lungs through the trachea which is a flexible tube of cartilage running from the larynx (voice box) to the lungs. It splits into two branches called bronchi, which feed the left and right lungs.
The Vocal Folds
The larynx contains the vocal folds (chords) which are muscles that run from front to back and can open to allow air through or close to seal the airway. When they are held together and air passes between them they vibrate to produce sound.
We tend to think that the primary function of the vocal folds is to produce sound for speaking and singing, but they in fact have another, more important function, which is to play a part in preventing food from entering the trachea and blocking it when we eat (which is a potentially deadly scenario!). When we breathe, the vocal folds are in an open position, but when we swallow they close to seal the airway so the food goes down the oesophagus rather than the trachea (see diagram below). They are assisted in this by the epiglottis which lies above the vocal folds and descends as the vocal folds close.
Because the vocal folds have this important — and life-saving — role in eating, there are very strong neurological and emotional connections between them and the tongue, and the muscles of the jaw and throat. These connections have significant ramifications for breathing, and especially for speaking and singing — there will be more about this in the next article.
The vocal folds, together with the 'false' vocal folds which sit above them, have a third important function. When our torso needs more support for activities such as lifting heavy weights, straining, expelling waste etc, they close and seal air inside the lungs. Because air is relatively hard to compress, the trapped air helps prevent the chest cavity from collapsing under the strain. This is assisted by muscles in the belly (particularly the rectus abdominus which runs from the breast bone to the front of the pelvis). These activate to support and ‘hold in’ the internal organs of the belly, which in turn supports the diaphragm so that pressure is maintained in the lungs. You can see this mechanism operating clearly if you imagine picking up a (very) heavy weight and grunt and seal your lungs in preparation.
The Pharynx, Mouth and Nasal Cavities
Moving further upwards from the larynx there is the pharynx, which divides into the mouth and the nasal cavity. The soft palate is suspended above the pharynx, and because this can be raised and lowered we can choose to let air come in through either the mouth or the nose.
All things being equal it is generally best for air to come in through the nose which has filter mechanisms to catch dust and particles. In addition, the nasal cavities act as ‘conditioners’ for the air. They have a large surface area and can adjust the air temperature to very close to that of the body. However sometimes mouth breathing is appropriate, for example when we need to take in a large amount of air quickly, or when speaking or singing.
In the next couple of posts I will explore ways in which many of us interfere with our (originally) very effective breathing mechanism. I will look at some of the problems can result and suggest what we can do — or more accurately ’not do’! — to improve matters.