The diaphragm is often referred to as a “postural muscle” when the Zone of Apposition is lost and the dome of the hemi-diaphragm lowers to the point of becoming tonically positioned with an ipsilateral anterior rib flare and hemilordosis. Can you explain exactly why it is referred to as a postural muscle in this case? I understand that it certainly becomes less of an effective respiratory muscle, but where exactly did that term come from?
The diaphragm is referred to as a “postural muscle” because without the ZOA the diaphragm becomes the primary stabilizer of the anterior spine. The left abdominals are gone so the diaphragm takes over as a postural stabilizer. The diaphragm is placed in a position at end range lumbar lordosis for lumbar-thoracic stability.