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Gross Respiratory Anatomy

  • The lungs occupy the lateral compartments of the thorax and exist within the pleural cavities. Between the lungs lies the mediastinum which contains the heart, esophagus, trachea, and the great vessels.
  • The right and left lungs have slightly distinct anatomies, largely as a result of the hearts asymmetric orientation toward the left side of the thorax. The lungs are divided into lobes, the right lung having three lobes while the left having two. The right lungs lobes are termed the superior, middle, and inferior lobes whereas the left lung only possesses a superior and inferior lobe. One way to remember why the left lung lacks a middle lobe is by appreciating that the heart largely takes up this space. Instead, the lefts superior lobe has an anterior extension that curves around the anterior heart termed the “lingula”.
  • The lungs are connected with the rest of the body at their “hilum” where airways, vasculature, and nerves enter and exit the organs. Here the trachea divides into right and left main bronchi that serve their respective lungs. This is also the location of the right and left pulmonary arteries, derived from the pulmonary trunk exiting the right heart. Each lung is drained by two pulmonary veins that in turn feed into the left atrium.
  • The lungs are covered by a thin serious membrane known as the visceral pleura that reflects around the structures of the hilum and then covers the thoracic wall and thoracic surface of the diaphragm, where it is termed the parietal pleura. This arrangement is similar to covering a lollipop with