Re: Re: diaphragm placement/bore size?

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Posted by Brian Frederiksen on April 17, 2002 at 19:21:20:

In Reply to: Re: diaphragm placement/bore size? posted by For the record.... on April 17, 2002 at 18:35:33:

Since I am the one who has this on their computer, here it is. This is from ARNOLD JACOBS: SONG AND WIND. Mr Jacobs approved and a doctor went over this.

The diaphragm is a muscular partition between the thoracic and the abdominal cavities. Its location, in the front, is at the base of the sternum [breastbone] and in the back on the spine and at the base of the rib cage.
During contraction, the diaphragm descends, the chest cavity is enlarged and air pressure is lowered. This is responsible for 75 percent of the normal volume increase of the lungs. It is a physical impossibility to use the diaphragm to raise intrathoracic pressure.
For deeper breathing the ribs are elevated and expanded outwards, further expanding the chest by the external intercostal muscles. Small increments in volume can be obtained by further elevation of the ribs by muscles of the neck and back.
Because the diaphragm can only move up and down, Jacobs commonly makes the analogy of the diaphragm to an old-fashioned insect sprayer. “With the bug sprayer, if you pull the handle out, the pressure decreases. If you push it in, the pressure increases—the diaphragm is like a piston.”
There are no nerves in the diaphragm to tell the brain what position it is in. The diaphragm has only pain sensing nerves.
Many teachers use the phrase, “blow from the diaphragm,” and use the term “diaphragmatic support.” “The term ‘support’ raises questions in itself. Many people make the mistake of assuming that muscle contraction is what provides support. The blowing of the breath should be the support, not tension in the muscles of the body, but the movement of air that is required by the embouchure or reed.
“Support is always a reduction phenomenon. Wherever the player is going to build pressure, according to Boyle’s Law, he is going to have a reduced chamber. The chamber can be reduced anywhere it is previously enlarged. It gets bigger when you take air in. It gets smaller when you move air out. When you blow, the brain will deactivate the diaphragm, normally. If you are using air to create pelvic pressures, the diaphragm will not deactivate—it will remain stimulated. Abdominal muscles that would normally be expiratory will start contracting, and there will be a closure at the throat or the tongue or the lips, which causes the air pressure to bear down on a downward-contracting diaphragm to increase the pelvic pressure for expulsion of fecal matter. Of course, to bypass this we have to have a blowing phenomenon that is different,” Jacobs says.

The ability of the diaphragm to move is directly related to the position of the body {see: Physical Elements: Posture}. The respiratory system should not be thought of as a single bellows, but as a series of segmented bellows. “If I lean to the right, the use of the right lung is diminished. By leaning to the left, the use of the left lung is diminished. By leaning backwards, the upper lung motion is diminished. By leaning forwards, the diaphragmatic activity is diminished [as less air can be taken in].”

Exhalation begins with the relaxation of the inspiratory muscles. During normal breathing, exhalation is passive. In forced exhalation, such as playing a wind instrument, the relaxed diaphragm is lifted by contraction of the abdominal muscles [neural inhibition] and the chest is drawn downwards and in by the internal intercostal muscles.
Breathing out can be inhibited by either contraction of the diaphragm [the paradox or perversity of “diaphragmatic support”], or by obstruction of an outflow at the larynx. Both these “brakes” are used during normal respiration and especially during straining maneuvers.

Emptying the lungs in a normal person may take only four seconds. Eighty percent of the air should be dischargeable within one second and the remainder in the next two or three seconds. By pulling in the lower abdomen, the diaphragm is forced up and a bit is forced out—something Jacobs does not recommend.
The best advice is to take in a full breath. Jacobs says, “There is no reason not to take a full breath—it’s free, it costs nothing.”

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