Thoracic diaphragmThe thoracic diaphragm, or simply the diaphragm (ˈdaɪəfɹæm; diáphragma), is a sheet of internal skeletal muscle in humans and other mammals that extends across the bottom of the thoracic cavity. The diaphragm is the most important muscle of respiration, and separates the thoracic cavity, containing the heart and lungs, from the abdominal cavity: as the diaphragm contracts, the volume of the thoracic cavity increases, creating a negative pressure there, which draws air into the lungs.
Rib cageThe rib cage is an endoskeletal enclosure in the thorax of most vertebrate animals that comprises the ribs, vertebral column and sternum, which protects vital organs such as the heart, lungs and great vessels. The circumferential enclosure formed by left and right rib cages, together known as the thoracic cage, is a semi-rigid bony and cartilaginous structure which surrounds the thoracic cavity and supports the shoulder girdles to form the core part of the axial skeleton.
Pulmonary pleuraeThe pulmonary pleurae (: pleura) are the two opposing layers of serous membrane overlying the lungs and the inside of the surrounding chest walls. The inner pleura, called the visceral pleura, covers the surface of each lung and dips between the lobes of the lung as fissures, and is formed by the invagination of lung buds into each thoracic sac during embryonic development.
Pleural cavityThe pleural cavity, pleural space, or interpleural space is the potential space between the pleurae of the pleural sac that surrounds each lung. A small amount of serous pleural fluid is maintained in the pleural cavity to enable lubrication between the membranes, and also to create a pressure gradient. The serous membrane that covers the surface of the lung is the visceral pleura and is separated from the outer membrane, the parietal pleura, by just the film of pleural fluid in the pleural cavity.
Muscles of respirationThe muscles of respiration are the muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. The elasticity of these muscles is crucial to the health of the respiratory system and to maximize its functional capabilities. Thoracic diaphragm The diaphragm is the major muscle responsible for breathing.
