The diaphragm, in its role as a musculoaponeurotic structure separating the thoracic and abdominal domains, is subject to injury following blunt or penetrating trauma. Historical accounts documenting diaphragmatic injury date from 1541, when Sennertus described the postmortem finding of delayed herniation of the stomach through a diaphragmatic defect in a patient who had previously suffered a penetrating chest wound. Detailed postmortem findings related to both blunt and penetrating diaphragmatic injuries were reported by Ambroise Pare in the sixteenth century. The first antemortem diagnosis of a traumatic diaphragmatic injury was published by H. I. Bowditch in 1853, who also set forth physical criteria for the diagnosis of traumatic diaphragmatic hernias: (1) prominence and immobility of the left thorax; (2) displacement to the right of the area of cardiac dullness; (3) absent breath sounds over the left thorax; (4) audible bowel sounds in the left chest; and (5) tympany to percussion over the left chest. Riolfi, in 1886, subsequently performed the first successful repair of a diaphragmatic laceration secondary to penetrating trauma. Hedblom, in 1925, reviewed 378 cases of diaphragmatic hernias in the surgical literature, providing a contemporary overview of diagnosis and surgical treatment.
The diaphragm (dia: across, phragm: fence) is the musculotendinous, dome-shaped structure separating the negative-pressure thoracic cavity and the positive-pressure peritoneal cavity. Embryologically, the diaphragm is derived from the fusion of four distinct structures: the septum transversum, the pleuroperitoneal membranes, the dorsal mesentery of the esophagus, and the body wall musculature. After development is complete, the diaphragm is composed of two distinct muscle groups, costal and crural. The costal muscle group is composed of peripherally located skeletal muscle fibers, whose contraction results in flattening of the diaphragm and lowering of the ribs. The crural muscle group, by contrast, does not contribute significantly to diaphragmatic excursion. The left crus arises from the upper two lumbar vertebrae and the right crus arises from the lateral aspect of the upper three lumbar vertebrae. The interdigitation of the medial tendinous crural fibers anterior to the aortic hiatus forms the median arcuate ligament, and the fibers of the right crus encircle the esophagus. Both costal and crural muscle fibers converge to insert into the aponeurotic central tendon, whose central aspect lies immediately beneath the pericardium (Fig. 154-1). Thoracoabdominal structures traverse the diaphragm through three major openings: the vena cava aperture (T8 vertebral level, containing the vena cava), the esophageal aperture (T10 vertebral level, containing the esophagus and the left and right vagal nerves), and the aortic aperture (T12 vertebral level, containing the aorta, thoracic duct, and the azygos vein (Fig. 154-2).
The muscle fibers of the diaphragm originate from the posterior lumbar spine (arcuate ligaments) and curve upward to form an aponeurotic sheath known as the central tendon. Several thoracic organs and vessels pass through apertures in the diaphragmatic surface.