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The most common reason for opening the chest is to remove a cancer of the lung. There are 168,000 new cases of lung cancer each year with a rising death rate. It is the most common cancer death in men and women. This statistic is even more dramatic when we realize that only 25% of these patients reach a surgeon in time. This is because carcinoma of the lung is the most aggressive type of cancer and, before major symptoms occur, the disease has commonly spread beyond the lung and thus out of the realm of surgical success. Anatomy and Physiology - The bony skeleton of the thorax, which surround the contents, is made up of
- The sternum (breast bone)
- Ribs
- Costal cartilages. The rib like pieces of cartilage that extend from the ribs to the sternum
- The thoracic spine
- These bones are held together by muscles and ligaments
- The top of the thorax is an open passage (thoracic inlet) to the structures in the neck
- The bottom of the thorax is the diaphragm
- With each breath (inspiration), the ribs rise up slightly to expand the chest, the diaphragm moves down toward the abdomen and air enters the lungs
- The reverse occurs with expiration. The ribs move down and the diaphragm moves upward to expel the gases in the lungs
- The thorax primarily contains the heart and lungs. For the anatomy related to the heart see Cardiac Catheterization and Coronary Artery Bypass Surgery
- The lungs are the organs of respiration and are divided on the right side into three lobes and on the left into two (Figure 1)
- Air enters the lungs through a system of tubes that begin in the neck
- The trachea (windpipe) is the tube which begins in the neck and carries air to the right and left bronchi
- The bronchi in turn divide into smaller tubes, the bronchioles. The bronchioles continue to divide and subdivide
- Eventually the smallest bronchioles lead to the alveoli
- Arteries associated with the lungs (pulmonary arteries) eventually lead to capillaries that are in contact with the alveoli
- Oxygen in the air of the alveoli exchanges with the carbon dioxide in the red blood cells in the capillaries
- Blood rich in oxygen is then carried to the heart by the pulmonary veins and pumped to the rest of the body
- The inside of the chest wall is covered by a thin layer of cells called the parietal pleura. The lung surface is likewise covered with a similar layer of cells called the visceral pleura. Between the two layers of pleura is a thin layer of fluid that acts as a lubricant so that the lung glides over the chest wall during breathing
- Between the two lungs lies a space, the mediastinum, occupied by the trachea and bronchi, the esophagus (tube to the stomach), the aorta, the pulmonary arteries and veins, and a series of lymph nodes. The lymph is a clear colorless fluid that drains from the tissues through thin walled channels to the nodes
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| Figure 1 - Anatomy of the
lungs showing the various lobes on the right and left side |
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