QS Study

diaphragm is a dome-shaped muscle forming the partition between the thoracic and abdominal cavities. It is the primary muscle used in respiration, which is the process of breathing. This dome-shaped muscle is located just below the lungs and heart.

Major openings of the diaphragm

Fig: Major openings of the diaphragm as seen from below

These are –

  1. Vena caval opening.
  2. Oesophageal opening.
  3. Aortic opening.

(1) Vena caval opening

It is situated in the central tendon at the junction of the median and right leaflets, about 2.5 cm to the right of the middle line. The inferior vena cava passes through the central tendon of the diaphragm at the level of the 8th thoracic vertebra.

Vertebral level: Opposite the disc between the T8 and T9 vertebrae.

Structures passing:

  1. Inferior vena cava.
  2. Few branches of the right phrenic nerve.
  3. Few lymph vessels from the liver

(2) Oesophageal opening

It is situated in the muscular part of the diaphragm about 1.25 cm to the left of the middle line. The esophagus passes through muscular fibers of the diaphragm slightly to the left of the midline at the level of the T10 vertebra.

Vertebral level: At the level of T 10 vertebra.

Structures passing:

  • Oesophagus.
  • Anterior and posterior vagal trunks.
  • Oesophageal branches of the left gastric artery.
  • Lymphatics.

(3) Aortic opening

It is situated behind the diaphragm slightly to the left of the middle line. The thoracic aorta passes through this opening between the crura of the diaphragm.

Vertebral level: At the level of T 12 vertebra.

Structures passing:

  1. Abdominal aorta
  2. Thoracic duct.
  3. Sometimes azygos vein.

Clinical importance of the openings –

Acquired hiatus hernias (oesophageal hernias) are common. These are found in a patient usually of middle age where weakening and widening of an oesophageal opening have occurred.

Sliding hernia: When the oesophagogastric junction slides upwards into the thorax.

A para-oesophageal hernia: When the stomach herniates into the thorax along the esophagus.