Diaphragm (Diaphragma)
Educational content only — not medical advice.
Anatomy
The dome-shaped musculotendinous septum between the thoracic and abdominal cavities and the principal muscle of respiration. Its peripheral muscle converges on the trefoil central tendon; its origins are sternal, costal and lumbar (crura down to the upper lumbar vertebrae), and the origins leave the aortic, esophageal and vena caval openings between them. It descends and flattens on contraction, drawing air into the lungs.
Origin & insertion
From the xiphoid process, the lower six ribs and their cartilages, and the upper lumbar vertebrae by right and left crura with the arcuate ligaments, into the central tendon.
Action
Principal muscle of inspiration: contracts, descends and flattens, increasing thoracic volume; also raises intra-abdominal pressure for coughing, defecation and lifting.
Innervation
Phrenic nerve (C3–C5); peripheral sensory supply from the lower intercostal nerves.
Clinical notes
"C3, 4, 5 keeps the diaphragm alive" — a high cervical cord injury stops respiration. Sliding hiatus hernia through the esophageal opening causes reflux; phrenic palsy makes the hemidiaphragm rise and move paradoxically on fluoroscopy; persistent hiccup is a phrenic-nerve irritative sign.
Related structures
Educational references
FAQ
What is the role of the Diaphragm?
The dome-shaped musculotendinous septum between the thoracic and abdominal cavities and the principal muscle of respiration. Its peripheral muscle converges on the trefoil central tendon; its origins are sternal, costal and lumbar (crura down to the upper lumbar vertebrae), and the origins leave the aortic, esophageal and vena caval openings between them. It descends and flattens on contraction, drawing air into the lungs.
Why is the Diaphragm clinically important?
"C3, 4, 5 keeps the diaphragm alive" — a high cervical cord injury stops respiration. Sliding hiatus hernia through the esophageal opening causes reflux; phrenic palsy makes the hemidiaphragm rise and move paradoxically on fluoroscopy; persistent hiccup is a phrenic-nerve irritative sign.
Source & license
BodyParts3D, © The Database Center for Life Science licensed under CC Attribution 4.0 International (https://creativecommons.org/licenses/by/4.0/). license details