Diaphragm (anatomy)

Diaphragm
Respiratory system
Details
Precursor	Septum transversum, pleuroperitoneal folds, body wall
Artery	Pericardiacophrenic artery, musculophrenic artery, inferior phrenic arteries
Vein	Superior phrenic vein, inferior phrenic vein
Nerve	Phrenic and lower intercostal nerves
Identifiers
Latin	Diaphragma
Greek	διάφραγμα
MeSH	A02.633.567.900.300
Dorlands /Elsevier	12293509
TA	A04.4.02.001
FMA	13295
Anatomical terminology []

In human anatomy, the thoracic diaphragm, or simply the diaphragm (Ancient Greek: διάφραγμα diáphragma "partition"), 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. In humans, the diaphragm is slightly asymmetric—its right half is higher up (superior) to the left half, since the large liver rests beneath the right half of the 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 the lungs in the abdominal cavity.

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.