Central tendonA thin, strong sheet shaped like a clover leaf. Every muscle fiber ends in it.
Costal partThe widest part of the muscle. It arises from the lower six ribs and their cartilages.
Sternal partTwo short slips from the back of the xiphoid process.
Lumbar partThe back of the muscle. It arises from the crura and the arcuate ligaments.
Caval openingThe opening for the inferior vena cava, at about T8. It lies in the central tendon.
Esophageal hiatusThe opening for the esophagus, at T10. Fibers of the right crus ring it.
Aortic hiatusThe gap for the aorta, between the crura, at T12.
Right crusA tendon pillar from the upper three lumbar vertebrae. Longer than the left.
Left crusA tendon pillar from the upper two lumbar vertebrae.
Crura and arches 3
Median arcuate ligamentAn arch that joins the two crura in front of the aorta.
Medial arcuate ligamentA tendon arch over the top of the psoas major.
Lateral arcuate ligamentAn arch over the quadratus lumborum, out to the twelfth rib.
What lies beside it 3
Xiphoid processThe lower tip of the breastbone, where the sternal part arises.
Psoas majorA muscle of the back wall of the abdomen. It passes under the medial arcuate ligament.
Quadratus lumborumA muscle of the back wall of the abdomen. It passes under the lateral arcuate ligament.
Dome and tubes, from the front 5
Right domeThe higher of the two domes. The liver lies under it.
Left domeThe lower of the two domes.
Inferior vena cavaPasses through the caval opening in the central tendon, at T8.
EsophagusPasses through the esophageal hiatus at T10, with the vagus nerves.
AortaPasses behind the diaphragm, between the crura, at T12.
How this list was compiled: Every name checked on 2026-10-01 in at least two of these, in our own words. (1) Henry Gray, Anatomy of the Human Body, 20th edition, 1918 (public domain), the Diaphragm, https://www.bartleby.com/107/117.html: the sternal, costal and lumbar parts; the medial and lateral lumbocostal arches over the psoas major and the quadratus lumborum; the crura and the arch they form across the aorta; the central tendon; the three large openings. (2) TeachMeAnatomy, The Diaphragm, https://teachmeanatomy.info/thorax/muscles/diaphragm/: the crura, the central tendon, the domes, the openings and their levels. (3) Kenhub, Diaphragm, https://www.kenhub.com/en/library/anatomy/diaphragm: the three parts, the arcuate ligaments, the openings, the domes. (4) Wikipedia, Thoracic diaphragm and Median arcuate ligament, https://en.wikipedia.org/wiki/Thoracic_diaphragm. Licence: own work
The drawing: Drawn for this site on 2026-10-01 from plain geometry. Own original drawing; nothing is traced or copied. Licence: own work
How it works
Label the diaphragm, the dome of muscle between the chest and the abdomen, on two drawings: its under surface seen from below, and the dome from the front with the three tubes that pass through it.
Read the full guide
From below
The fibers arise in three parts: sternal, from the xiphoid process; costal, from the lower ribs; and lumbar, from the two crura and the arcuate ligaments. All of them end in the central tendon. The view is from below with the breastbone at the top, so the body's right side is on your left.
The three openings
The caval opening lies in the central tendon at about T8, the esophageal hiatus in the muscle at T10 and the aortic hiatus between the crura at T12. The second drawing shows the inferior vena cava, the esophagus and the aorta passing through at those levels.
Questions and answers
What are the parts of the diaphragm?
A central tendon and three muscular parts named for where they arise: the sternal part, the costal part and the lumbar part. The lumbar part includes the right and left crura, the two pillars on the spine.
What passes through the three openings of the diaphragm?
The caval opening carries the inferior vena cava, the esophagus and the vagus nerves through the esophageal hiatus, and the aorta, with the thoracic duct and the azygos vein, through the aortic hiatus.
What are the crura of the diaphragm?
Two tendon pillars that fix the diaphragm to the spine. In Gray's Anatomy the right crus, the larger and longer, arises from the upper three lumbar vertebrae and the left crus from the upper two.
Is this the diaphragm of a microscope?
No. This page draws the muscle under the lungs. The diaphragm of a microscope, which controls the light, is one of the parts on the microscope diagram.