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Central tendon
The diaphragm. Under surface. (Central tendon visible as large white central arch.)
The thoracic aspect of the diaphragm of a newly born child in which the communication between the peritoneum and pleura has not been closed on the left side; the position of the opening is marked on the right side by the spinocostal hiatus.
Latin	centrum tendineum diaphragmatis
Gray's	subject #117 406
Precursor	septum transversum
Dorlands/Elsevier	c_20/12227367

The central tendon of the diaphragm is a thin but strong aponeurosis situated near the center of the vault formed by the muscle, but somewhat closer to the front than to the back of the thorax, so that the posterior muscular fibers are longer.

It is situated immediately below the pericardium, with which it is partially blended.

It is shaped somewhat like a trefoil leaf, consisting of three divisions or leaflets separated from one another by slight indentations.

The right leaflet is the largest, the middle, directed toward the xiphoid process, the next in size, and the left the smallest.

In structure the tendon is composed of several planes of fibers, which intersect one another at various angles and unite into straight or curved bundles—an arrangement which gives it additional strength.

During inspiration the diaphragm contracts causing the central tendon to be drawn inferiorly which partially flattens the domes. The result is an enlargement of thoracic cavity and reduction in intra-thoracic pressure. Physiologically this means that air enters the lungs and venous return to the heart is enhanced. During inspiration the central tendon retains its shape due to its tendonous nature and prevents constriction of the inferior vena cava or aorta, however the oesophagus is surrounded by muscle at the oesophageal hiatus and is constricted (food is difficult to swallow with inspiration).

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This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.