What are the four embryological components that form the diaphragm?

The diaphragm develops from the fusion of four sources: septum transversum (forms the central tendon), pleuroperitoneal membranes (close the pleuroperitoneal canals), dorsal mesentery of the esophagus (gives rise to the crura), and mesoderm of the body wall (forms the peripheral muscular parts).

Why does the phrenic nerve (C3, C4, C5) innervate the diaphragm even though it descends to a lower position?

During development, the diaphragm originates in the cervical region opposite spinal segments C3–C5, where it receives innervation from the phrenic nerve. As it descends to the thoracoabdominal junction, the phrenic nerve remains attached, maintaining its nerve supply despite the change in position.

What is congenital diaphragmatic hernia (CDH) and why is it clinically significant?

Congenital diaphragmatic hernia (CDH) is a birth defect where abdominal contents herniate into the thoracic cavity through a posterolateral defect called the foramen of Bochdalek. It often leads to pulmonary hypoplasia and severe respiratory distress in newborns, requiring urgent medical attention.

How does the nerve supply differ between the central and peripheral parts of the diaphragm?

The central part of the diaphragm is supplied by the phrenic nerve (C3, C4, C5), while the peripheral parts receive sensory innervation from lower intercostal nerves. This difference arises because the peripheral parts originate from the lateral body wall mesoderm.

What is eventration of the diaphragm and what causes it?

Eventration of the diaphragm is a condition where one half of the diaphragm is thin, membranous, and balloons into the thoracic cavity. It is caused by failure of muscle development during embryogenesis, often occurring on the left side.

What are the different types of congenital diaphragmatic hernias mentioned?

The article describes three types: congenital diaphragmatic hernia (CDH) through the foramen of Bochdalek, congenital hiatal hernia through an enlarged esophageal hiatus, and retrosternal (Morgagni) hernia between sternal and costal parts.

Diaphragm Development – 4 Embryonic Components