What is the diaphragm?
The diaphragm is the main muscle used in breathing and is also the largest muscle in our body. This dome-shaped muscle is located just below the thoracic cavity and divides this cavity from the abdominal cavity below it. In our every respiratory act it contracts, flattens and lowers and relaxes, expanding and rising, with each inhalation and exhalation.
During its inspiratory moment it creates a vacuum effect which draws air into the lungs. On exhalation it relaxes due to the recoil effect of the abdominal muscles and the air is pushed out of the lungs.
It's good to know though that the diaphragm also has some non-respiratory functions, it increases abdominal pressure to help the body get rid of vomit, urine and feces. It also puts pressure on the esophagus to prevent acid reflux. Its movements are controlled by the phrenic nerve.
There are three large openings in the diaphragm (sphincters) that allow passage of certain structures between the chest and abdomen.
These openings are:
• Esophageal sphincter: The esophagus and vagus nerve, which control much of the digestive system, pass through this opening.
• Aortic sphincter: The aorta, the body's main artery that carries blood from the heart, passes
In this opening. The thoracic duct, a major vessel of the lymphatic system, also passes through this sphincter.
• Caval sphincter: The inferior vena cava, a large vein that carries blood to the heart, passes through this opening.
Valentina Carlile - Osteopath expert in Osteopathy applied to voice and speech disorders since 2002. For information and reservations visit the page Contacts