Central Diaphragm
Breathing works the diaphragm in tandem with the intercostal muscles. These are the muscles between the ribs and the abdominals. The diaphragm is responsible for 75 percent of respiratory energy and is a large, thin dome-shaped muscle that's directly below the heart and separates the thoracic abdominal cavities. The diaphragm billows like a parachute by contracting and expanding the chest cavity.
Actions
When you inhale, the diaphragm and intercostal muscles--the muscles between your ribs--contract and expand the chest cavity. This expansion lowers the pressure in the chest cavity, and oxygen flows through and inflates the lungs. When you exhale, the diaphragm and intercostal muscles relax and the chest cavity gets smaller. Oxygen from the lungs flows out of the airways to the outside air. The cycle repeats with each breath.
Interconnected
The lungs and heart sit above the diaphragm, and the liver, spleen, stomach, large intestine, small intestine and bladder sit below. When the diaphragm is free to move, the organs are massaged and rejuvenated with new blood, fluids and oxygen.
The movement of the diaphragm, like the heart, is regulated by the autonomic nervous system so breathing is an unconscious action--although stress, tension, anxiety and "fight or flight" feelings obstruct the fluidity of breathing. A diaphragm is any muscular, membranous or ligamentous wall that divides two spaces in the body. The central diaphragm, the pelvic diaphragm and the vocal diaphragm all work in facilitating breathing.
The pelvic diaphragm sits at the base of the pelvis, carries the weight of the pelvic organs and dynamically closes the rectum. The vocal diaphragm is disc-shaped and sits between the base of the tongue and trachea. The three diaphragms' synchronistic energy is important to full-body breathing.
Feeling it All Work
You may notice your voice is squeaky when you're nervous. What happens is, you're subconsciously narrowing the vocal diaphragm and forcing breath only to the upper chest, as clenching the anus muscles obstructs the full descent of the primary diaphragm. Noticing all three diaphragms working together is an exercise to bring awareness to the subtleties and interconnectedness.
Feeling how breathing works is a good way to realize the power of the diaphragms working jointly, or sometimes working against one another. Sit on a chair with a tall spine and feet planted on the floor. Breathe and notice the belly expanding and contracting. Then hold your abdomen in as if sucking in your stomach and notice the diaphragm trying to descend. Because there's a blockage in the pelvic diaphragm, the secondary respiratory muscles are working to compensate. Then release, and tense the throat as if holding back tears and notice the strain on the diaphragm to ascend fully.
References
- "The Breathing Book"; Donna Farhi; 1996
- "The Key Muscles of Hatha Yoga"; Ray Long, MD FRCSC; 2006
