The Respiratory Diaphragm

~The most important muscle in our body~


(photo courtesy of Essential Anatomy 5 app.  Must have for anatomy lovers)

Why is the respiratory diaphragm the body’s most important muscle?

The respiratory diaphragm is our “breathing muscle” and if it stops working, you won’t last too long without a ventilator to breath.


the diaphragm attaches to the under surface of the lower six ribs and then inserts on the lumbar spine of L1-3 on the right and L1-2 on the left.

How does it work?  

During inhalation, the diaphragm descends, or drops, producing expansion of the thorax and compression of the abdominal cavity.  This muscular contraction creates a decrease in the intrathoracic pressure which in turn causes the air to flow into the alveoli of the lungs by the way of the trachea.

Clinical importance:

  • Primary mode of breathing, cannot survive without it
  • This is the direct link between your mid back and lumbar spine and connects us fascially to the quadratus lumborum and  psoas (which, in turn, attaches to the hip).
  • Helps to influence our nervous system and dampen the effects of stress by reducing sympathetic tone.
  • The innervation of the diaphragm stems from the Phrenic nerve of the cervical spine (C3-5). We now have a connection of the cervical, thoracic, and lumbar spine.
  • Lymphatic flow is improved with better mobility and function of the diaphragm.
  • Stiffness of the thoracic spine is often implicated in lower back pain.
  • Better oxygenation and perfusion of the tissues occur with an optimally functioning respirator diaphragm.  

Bottom line:

In order for us to be as functional as possible, we must have a fully functioning respiratory diaphragm.  As clinicians, we are responsible for assessing, treating, and giving our clients exercises to help them improve their overall breathing mechanics and wellbeing.

Always open for any questions,


Ed Deboo,PT

Bellingham Physical Therapy