Dysfunction of the Diaphragm

Imaging as a Diagnostic Tool

Nadir Kharma


Curr Opin Pulm Med. 2013;19(4):394-398. 

In This Article

Function of the Diaphragm

Ventilation relies primarily on the contractility of the diaphragm. Other accessory muscles including the external intercostal, sternocleidomastoid and scalene muscles also aid the diaphragm during inspiration. As inspiration is an active process, the thoracic cavity expands during the contraction of the diaphragm. This is achieved by creating a negative intrathoacic pressure, which in turn facilitates the movement of air into the lungs. Exhalation is a passive process. It takes place when the diaphragm relaxes, thus allowing the lungs to decrease in size by virtue of its elastic recoil.

The diaphragm has several other nonrespiratory functions as well. By increasing intraabdominal pressure, the diaphragm can help with vomiting, urination and defecation. By exerting pressure at the oesophageal hiatus, it prevents gastroesophageal reflux.[5]