diafragma

Diafragma, also anglicized as diaphragm, is a term used in biology, optics, and engineering to denote a flexible membrane or partition that regulates separation or flow. In anatomy, the diaphragm is a large, dome-shaped muscle that separates the thoracic and abdominal cavities and is essential for breathing. It attaches to the sternum, lower ribs, and the lumbar spine via the crura, with a central tendon as the insertion point. The diaphragm is mainly innervated by the phrenic nerves (C3–C5). Its contraction flattens the muscle and expands the thoracic cavity, drawing air into the lungs; relaxation allows air to be expelled. It also helps regulate intra-thoracoabdominal pressure during activities such as sneezing, vomiting, and childbirth.

Optical diaphragm refers to the adjustable aperture inside a camera lens or other optical instruments. It consists of overlapping blades that form an opening, whose size is expressed as f-stops. A larger aperture (smaller f-number) lets in more light and produces a shallower depth of field, while a smaller aperture (larger f-number) reduces light and increases depth of field. In modern cameras, the diaphragm is typically controlled automatically but can be adjusted manually on many lenses.

Other uses include a flexible membrane in various devices such as diaphragm pumps and pressure sensors, and the female diaphragm, a barrier method of contraception. In many languages the term diafragma is used to refer to the diaphragm in either sense, with context often indicating whether the reference is anatomical, optical, or mechanical.