"Cross-section of thorax. A, bronchus, entering the lung; B, the aorta cut at its origin and again at the descending part of its arch; C, the pericardial space; D, the pleural cavity; E, the alimentary canal; PA, the pulmonary artery; X, the neural canal." —Martin, 1917

Thorax

"Cross-section of thorax. A, bronchus, entering the lung; B, the aorta cut at its origin and again at…