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In human anatomy, the thoracic diaphragm, or simply the diaphragm (), is a sheet of internal skeletal muscle that extends across the bottom of the thoracic cavity. The diaphragm separates the thoracic cavity containing the heart and lungs, from the abdominal cavity and performs an important function in respiration: as the diaphragm contracts, the volume of the thoracic cavity increases and air is drawn into the lungs. The term "diaphragm" in anatomy can refer to other flat structures such as the urogenital diaphragm or pelvic diaphragm, but "the diaphragm" generally refers to the thoracic diaphragm. Other mammals have diaphragms, and other vertebrates such as amphibians and reptiles have diaphragm-like structures, but important details of the anatomy vary, such as the position of lungs in the abdominal cavity. ==Structure== The diaphragm is a dome-shaped structure of muscle and fibrous tissue that separates the thoracic cavity from the abdomen. The dome curves upwards. The superior surface of the dome forms the floor of the thoracic cavity, and the inferior surface the roof of the abdominal cavity.〔 As a dome, the diaphragm has peripheral attachments to structures that make up the abdominal and chest walls. The muscle fibres from these attachments converge in a ''central tendon'', which forms the crest of the dome.〔 Its peripheral part consists of muscular fibers that take origin from the circumference of the inferior thoracic aperture and converge to be inserted into a central tendon. The muscle fibres of the diaphragm emerge from many surrounding structures. At the front, fibres insert into the xiphoid process and along the costal margin. Laterally, muscle fibers insert into ribs 6-12. In the back, muscle fibres insert into the vertebra at T12 and two appendages, the right and left crus, descend and insert into the lumbar vertebrae at L1 & L2.〔 There are two lumbocostal arches, a medial and a lateral, on either side. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thoracic diaphragm」の詳細全文を読む スポンサード リンク
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