Diaphragm (optics) the lens. The centre of the diaphragm's aperture coincides with the optical axis of the lens system. Most modern cameras use a type of adjustable diaphragm known as an iris diaphragm, and often referred to simply as an iris. See the articles on aperture and f-number for the photographic effect and system of quantification of varying the opening in the diaphragm. A natural optical system that has a diaphragm and an aperture is the human eye. The iris is the diaphragm, and the opening in the iris of the eye (the pupil) is the aperture. An analogous dev in a
Thoracic diaphragm from the lower internal intercostal arteries. From below, the inferior phrenic arteries supply the diaphragm. The diaphragm drains blood into the brachiocephalic veins, azygos veins, and veins that drain into the inferior vena cava and left suprarenal vein. The sternal portion of the muscle is sometimes wanting and more rarely defects occur in the lateral part of the central tendon or adjoining muscle fibers. The thoracic diaphragm develops during embryogenesis, beginning in the third week after fertilization with two processes known as transverse folding and longitudinal folding. The septum transversum, the primitive central tendon of the diaphragm, originates at the