Respiratory Diaphragm

October 20, 2012 | By | Reply More

Respiratory Diaphragm

Includes right dome that arches superiorly to fifth rib and left dome that arches to fifth intercostal space and receives motor and sensory innervation from phrenic nerves except for peripheral part with sensory supply from lower intercostal nerves.

Phrenic nerves (C3,4,5) innervate the respiratory diaphragm.

Development of respiratory diaphragm occurs by incorporation of derivatives from the following four embryonic structures.

  1. Septum transversum
    • (1) Lies in cervical region in week 4, adjacent to third, fourth, and fifth cervical somites, which accounts for innervation of diaphragm by phrenic nerves (C3,4,5)
    • (2) Descends into thoracic region between developing heart and liver due to differential growth
    • (3) Gives rise to central tendon and to myoblaststhat migrate into pleuroperitoneal membranes and esophageal mesentery

      Diaphragm origins: septum transversum, pleuroperitoneal membranes, esophageal mesentery, and body wall mesoderm


  2. Pleuroperitoneal membranes
    • (1) Mesodermal tissue of posterior body wall that closes pericardioperitoneal canals by fusing with septum transversum and dorsal mesentery of esophagus
    • (2) Partition pleural cavity from peritoneal cavity

      Intraembryonic body cavity divided into pericardial, pleural, and peritoneal cavities by pleuropericardial and pleuroperitoneal membranes

  3. Esophageal mesentery
    • (1) Forms middle of diaphragm posteriorly
    • (2) Invaded by myoblasts that give rise to crura of diaphragm
  4. Body wall mesoderm
    • Forms peripheral part of diaphragm as a result of excavation by developing lungs and pleural cavities


Central tendon Receives insertions of sternal, costal, and lumbar parts Cloverleaf-shaped central aponeurotic part
Median arcuate ligament Unites crura across midline anterior to aorta
Medial arcuate ligament Body to transverse process of L1 Arches over psoas major
Lateral arcuate ligament Transverse process of L1 to rib 12 Arches over quadratus lumborum
Right crus Bodies of vertebrae L1-3 Larger and longer than left crus
Left crus Bodies of vertebrae L1-2
Vena caval hiatus Through central tendon at T8 vertebral level Transmits inferior vena cava and right phrenic nerve
Esophageal hiatus Through right crus at T10 level; left of midline Transmits esophagus, vagal trunks, and esophageal branches of left gastric vessels
Aortic hiatus Between crura behind median arcuate ligament at T12 level Posterior to diaphragm so movements don’t affect aortic flow; transmits aorta, thoracic duct, maybe azygos vein

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Category: Anatomy

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