The space in the thoracic cavity between the concave inner surfaces of the lungs, in which (in a special pericardial cavity) the heart is located, is called the mediastinum. The thoracic cavity is lined with a serous membrane called the pleura. The lungs are enclosed in the so-called pleural cavities, which are separate in man but communicate with one another in the majority of mammals. The shape of the thoracic cavity depends upon the shape of the thorax and the position of the diaphragm.
We sell 5 hammock sizes on the Traditional Hammocks (no spreader wood bars). Therefore, the length of the hammock is the same for each size but the difference is the width. Width gives the size. The larger the size, the wider and bigger the hammock.
Hammocks that are sold as extra large because they are 14 or 15 feet long, are only longer in the arms, not in the bed, which is a fixed 2 meters in size for all hammocks. It is possible to keep weaving a hammock until it is 20 feet or 100 feet wide; but of course, there is no practical reason to do so.