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Thoracic surface of the diaphragm

Learning objectives

Completing this study unit will help you to:

  1. Describe the anatomical location and function of the diaphragm.
  2. Identify the various structures of the diaphragm seen on its thoracic surface.
  3. List the openings of the diaphragm and name the structures which pass through them.

Watch video

The diaphragm is a large, dome-shaped, musculotendinous structure that separates the thoracic cavity from the abdominal cavity. Its muscle fibers originate peripherally and travel inwardly towards their insertion at the right and left central tendons. Contraction of this large muscle is vital for respiration, as it flattens the dome-like structure of the diaphragm and thus expands the thoracic cavity, allowing air to flow into the lungs.

The diaphragm is innervated by the left and right phrenic nerves, which arise from spinal nerves C3 to C5. There are a number of apertures, or openings, which allow structures to pass through the diaphragm and enter or leave the thoracic cavity. The three major openings are named after the structures that pass through them: the aortic hiatus, esophageal hiatus and caval foramen.

Watch the following video to learn more about the various features of the diaphragm as well as its anatomical relations to neighbouring organs:

Take a quiz

Are you ready to turn that newly acquired knowledge into long term memory? Do so with the quiz below.

Try out this customizable quiz and test yourself not only on the thoracic but also the abdominal surface of the diaphragm!

Browse atlas

Have another look at each of the individual structures associated with the thoracic surface of the diaphragm in the gallery below.


Key points about the thoracic surface of the diaphragm
Parts Skeletal muscle (sternal, costal and lumbar parts), central tendon
Function Main muscle responsible for respiration; increases abdominal pressure to expel feces, vomit and urine; applies pressure on the esophagus to prevent acid reflux
Relations Parietal pleura, pericardium
Openings (apertures) Aortic hiatus: Aorta, azygos vein, thoracic duct
hiatus: Esophagus, branches of the left gastric artery and vein, anterior and posterior vagal trunks
foramen: Inferior vena cava, branches of the right phrenic nerve
Innervation Left and right phrenic nerves (C3-C5)

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