- The upper part of the trunk between the neck and the abdomen; it is formed by the 12 thoracic vertebrae, the 12 pairs of ribs, the sternum, and the muscles and fasciae attached to these; below, it is separated from the abdomen by the diaphragm; it contains the chief organs of the circulatory and respiratory systems. [L. fr. G. t., breastplate, the chest, fr. thoresso, to arm]- barrel-shaped t. increased anteroposterior dimension of the t., so that lateral and anteroposterior dimensions are about equal, due to hyperinflation of the lungs. Seen in patients with emphysema.
* * *1) the part of the mammalian body that is situated between the neck and the abdomen and supported by the ribs, costal cartilages, and sternum also THORACIC CAVITY2) the middle of the three chief divisions of the body of an insect also the corresponding part of a crustacean or an arachnid
* * *n.the chest: the part of the body cavity between the neck and the diaphragm. The skeleton of the thorax is formed by the sternum, costal cartilages, ribs, and thoracic vertebrae of the backbone. It encloses the lungs, heart, oesophagus, and associated structures. Compare abdomen.• thoracic adj.
* * *tho·rax (thorґaks) gen. thoґracis pl. thoґraces [Gr. thōrax] 1. [TA] chest: the part of the body between the neck and the thoracic diaphragm, encased by the ribs. 2. cavitas thoracis.
Medical dictionary. 2011.