By Sanjeev Patel, CYT 500

Three muscle groups are involved during Pranayama. The understanding of anatomy is crucial for Yoga teachers who wish to improve their teaching skills. As Yoga teachers, we don’t learn anatomy to impress our students with big words, but it helps to understand what is happening under the surface of a technique.  As a result of these efforts to understand anatomy, Yoga classes will be a safe environment for all students.

Muscle Groups Involved in the Function of Pranayama

1. The function of the intercostal muscles during breathing are as follows: located between the ribs, the intercostal muscles operate as a unit to expand and contract the chest. Two sets of these muscles, one under the other, act on the rib cage. The external intercostal muscles run between the ribs in the same direction as the most external sheet of abdominal muscles, they lift and expand the rib cage for inhalation, like the movement of an old fashioned pump handle as it is lifted up from its resting position. The internal intercostal muscles run right angles to the external layer, they pull the ribs closer together as well as down and in for exhalation (usually a forced exhalation). If you place your hands on your chest with the fingers pointed down and medially (toward the midline of the body), this approximates the orientation of the internal intercostal muscles. The external intercostal muscles do not always act concentrically to lift the rib cage, during quiet breathing they also act isometrically to keep the rib cage from collapsing inward when the respiratory diaphragm creates the vacuum that draws air into the lungs.

2. The abdominal muscles function mainly in deep and forced exhalations, as when you try to blow up a balloon in one breath. For that task the muscles shorten concentrically, pressing in the abdominal wall inward, which in turn pushes the abdominal organs up against the relaxed (or relaxing) diaphragm. In combination with the action of the internal intercostal muscles, this forcibly decreases the action of the abdominal muscles by pursing the lips and forcing the breath out through the tiny opening. In yoga the abdominal muscles are important for what yogis refer to as even breathing, and they are also key elements for many breathing exercises.

3. The diaphragm is a domed sheet of combined muscle and tendon that spans the entire torso and separates the chest cavity from the abdominal cavity. Its rim is attached to the base of the rib cage and to the lumbar spine in the rear. The diaphragm is shaped like an umbrella, or an upside down cup, except that it is deeply indented to accommodate the vertebral column. It consists of central tendon, a costal portion and a crural portion. The dome of the ‘cup’ including the central tendon, descends and flattens during inhalation, putting pressure on the contents of the abdomen and creating a slight vacuum in the chest that draws air into the lungs. By contrast, the dome of the diaphragm is drawn upward during exhalation by the inherent elasticity of the lungs, and as that happens air escapes into the atmosphere.

Whenever the chest and spine position, the top of the dome of the diaphragm is pull straight downward during inhalation, like a piston, with the chest wall acting as the cylinder. During a supine inhalation the fibers of the diaphragm shorten concentrically and pull the central tendon inferiorly. During a supine exhalation its fibers lengthen eccentrically as the central tendon is both pushed from below and pulled from above, pushed by gravity acting on the abdominal organs and pulled by the elastic recoil of the lungs. The abdominal wall remains relaxed, it stretches out anteriorly as the dome of the diaphragm descends during inhalation, and it moves back posteriori (toward the back of the body) as the diaphragm relaxes and rises during the exhalation. Only in supine and inverted postures do we see the diaphragm act with such purity of movement. This kind of breathing is carried out in its entirety by the diaphragm, but it is often referred to as abdominal breathing, or belly breathing, because it is where movement can be seen and felt. It is also known as deep diaphragmatic breathing in recognition of its effects in the lower abdomen. Finally, we can call it abdomino-diaphragmatic breathing to indicate that the downward movement of the dome of the diaphragm not only draws air into the lungs, it also pushes the lower abdominal wall anteriorly.

In contrast to the pump handle analogy for intercostal breathing, diaphragmatic breathing has been linked to lifting a bucket handle up and out from its resting position alongside the bucket. Without the resistance of the abdominal organs, the diaphragm cannot create this result. The intercostal muscles serve to support the action of the diaphragm, not so much to lift and enlarge the chest but to keep it from collapsing during inhalation.

To summarize, diaphragmatic breathing occasions an expansion of the rib cage from its lower border. To differentiate it from abdomino-diaphragmatic breathing, in which the rib cage remains static, we can call it thoraco-diaphragmatic breathing.

Hari Om Tat Sat

© Copyright 2010 – Sanjeev Patel / Aura Wellness Center – Publications Division

Sanjeev Patel is a certified Yoga teacher and an exclusive author for Aura Wellness Center.

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