In Exercise Two, the external and internal structure of the thoracic wall and the contents of the thoracic cavity will be examined. The major organs of the thoracic cavity, the heart and lungs, will be removed and studied. The remaining structures that lie within or pass through the thoracic cavity will also be examined.

The heart is a thought provoking organ. Take a moment to realize that the heart you hold has been beating for many years. Assume a normal life span of 60 to 70 years at a rate of 65 beats per minute, calculations will reveal you are holding a muscle that has contracted over two and one half billion times. In that time it has undoubtedly "soared" and "been broken" many times. Ancient people believed the emotions came from the heart - perhaps they do!