The Diaphragm

Abstract

That the diaphragm is commanding more and more attention on the part of physicians and surgeons is evidenced by the greater frequency of requests for information regarding its condition. This is due to the following reasons. 1. The diaphragm is frequently the seat of congenital defects and anomalies because of faulty embryonal development which may result in herniation or displacement of abdominal organs into the thoracic cavity. 2. The diaphragm contains several openings for the passage of important structures between the thoracic and abdominal cavities. These openings, especially the esophageal, often become lax, resulting in herniation of a part or the whole of the stomach into the thoracic cavity. There is some evidence that the reverse of this, cardiospasm, is due to spasm of the esophageal opening. 3. The diaphragm is a thin musculotendinous membrane serving as the floor of the thoracic cavity and the roof of the abdominal cavity, as well as its upper posterior wall, but it does not accord with the usual conception of a rigid floor, roof, or wall, being relatively unstable and readily affected by pressure from above or below. 4. The diaphragm is in intimate relationship with the pleura, lungs, pericardium, and heart above, and with the liver, spleen, stomach, pancreas, kidneys, and often the colon below. It is evident that any enlargement of these structures may affect its position and mobility. General enlargement of the abdomen due to air, fluid, or large abdominal tumors will produce the same effect. 5. The diaphragm is the most important organ of respiration. Any deviation from the normal rate and degree of excursion may be readily observed fluoroscopically and the probable underlying cause determined. 6. The diaphragm is constantly under a physical strain in maintaining a proper balance between the positive abdominal pressure and the negative thoracic pressure. Any abnormal condition either above or below may readily upset this balance, resulting in change in position and impairment or cessation of mobility. From the foregoing observations, it is evident that the diaphragm, both anatomically and physiologically, is a vulnerable structure, being readily involved by pathological changes arising from above and below and as a result of the inherent weakness of the structure itself. Roentgen study has, indeed, advanced our knowledge of the diaphragm, but so far the greatest attention seems to have been paid to the anteroposterior projection. This would ordinarily be sufficient if the surface of the diaphragm were horizontal throughout, but such is not the case. The two leaves have the shape of domes; the highest points are located medially and anteriorly, and from these there is a downward slope in the lateral and backward extensions. Therefore, in an anteroposterior view only the surface of the highest level can be seen; the rest is out of sight.