Central tendon of diaphragm
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The muscle fibers of the diaphragm converge and attach to the central tendon of the diaphragm. It is a thin but strong layer of aponeurosis which forms an intergral part of respiration.
The central tendon of the diaphragm is located near the center of the diaphragmatic muscle but lies more anteriorly than posteriorly, meaning the posterior muscle fibers are longer than the anterior fibers 1. It is shaped like a club on a deck of cards. It has three leafs which are separated by small indentations. The right leaf is the largest, the middle is the second largest and directed anteriorly towards the xiphisternum and the left leaf is the smallest.
The central tendon of the diaphragm is composed of interlaced fibers which join at various angles to form bundles which give it its strength. It lies just inferiorly to the fibrous pericardium to which it is embryonically identical and inseparable 2.
The vena caval foramen passes through the tendon at the level of the T8 vertebra, posterior to the 6th costal cartilage and to the right of the midline 1. The inferior vena cava and right phrenic nerve pass through this opening.
With inspiration the central tendon is drawn inferiorly by the diaphgram. This expands the chest cavity and creates negative inter-thoracic pressure allowing air to enter the lungs 3. The inferior vena cava is not compressed in the foramen due to its tendinous nature.
- 1. Gray Henry, T. Pickering Pick and Robert Howden. Anatomy, descriptive and surgical. 39th ed. New York: Bounty Books, 1977
- 2. Sinnatamby, C. and Last, R. Last's anatomy. 12th ed. Edinburgh: Churchill Livingstone/Elsevier, 2011
- 3. West J. Respiratory physiology - the essentials. 9th ed. Philadelphia: Wolters Klower/Lippincott Williams and Wilkins, 2011