QS Study

Central tendon

It is a thin, strong aponeurosis of closely interwoven fibers of the muscles near the center of the diaphragm. During inspiration the diaphragm contracts causing the central tendon to be drawn inferiorly which partially flattens the domes. It is a thin but strong layer of aponeurosis which forms an integral part of respiration.

Location

It lies at the level of the lower end of the sternum (6th costal cartilage). It 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.

Fig: Central Tendon

Features

(i) The tendon is trilobar in shape, made up of three leaflets. The diaphragm has three “holes”, one each for the aorta, the esophagus and the vena cava.

(ii) The middle leaflet is triangular in shape with its apex directed towards the xiphoid process.

(iii) The right and left leaflets are tongue-shaped and curved laterally and backward, the left being a little narrower than the right.

(iv) The central area consists of four well-marked diagonal bands which fan out from a central point of decussating located in front of the opening for the oesophagus.

(v) The central tendon is an aponeurosis which forms the top of the dome-shaped diaphragm. It blends with the fibrous pericardium above, helping to maintain it in place.

Development – From septum transversum. It is composed of interlacing fibers that arise from the lumbar vertebrae, the costal margin, and the xiphoid process of the sternum.