ABSTRACT
INTRODUCTION The bony-cartilaginous skeleton of the thorax protects the heart, lungs and great vessels. It is conical, with a narrow inlet superiorly and a wide outlet inferiorly, and is formed of 12 thoracic vertebrae posteriorly, the sternum anteriorly, and 12 pairs of ribs with costal cartilages medially. The thoracic inlet, 10 cm wide and 5 cm anteroposteriorly, slopes downwards and forwards and is bounded by the 1st thoracic vertebra posteriorly, the upper border of the manubrium anteriorly, and the first rib and costal cartilage anteriorly. It transmits the oesophagus, the trachea and the great vessels of the head and neck, and on each side lies the dome of the pleura. The tho-
racic outlet too is widest from side to side, and is bounded by the 12th thoracic vertebra posteriorly, the 11th and 12th ribs posteriorly, and the costal cartilages of the 7th, 8th, 9th and 10th ribs, which ascend to meet the sternum anteriorly (Fig. 1.1). The diaphragm separates the thorax from the abdomen.
