Systemic arterial blood supply to the trachea and lung in sheep.

We studied the systemic arterial blood supply to the trachea and lung in adult sheep. After anesthesia, sheep were exsanguinated and then studied by intra-arterial injection of one of the following materials: saline containing dyes of various colors (n = 24), Microfil (n = 8), or Batson's solution (n = 6). The systemic blood supply to the cervical trachea originated from the two common carotid arteries via three to four small branches (rami tracheales cervicales) on each side. A segment of the thoracic trachea between the thoracic inlet and the origin of the tracheal bronchus (bronchus trachealis) and the bronchial tree of the right cranial lobe (lobus cranialis dexter) were supplied by the tracheal bronchial branch (ramus bronchalis trachealis), which originated from the brachiocephalic trunk (truncus brachiocephalicus). A portion of thoracic trachea between the origin of the tracheal bronchus and the tracheal carina was supplied by the thoracic tracheal branch (ramus trachealis thoracica), arising from the bronchoesophageal artery (arteria bronchoesophagea) or directly from the thoracic aorta. The bronchial branch (ramus bronchalis) originated from the bronchoesophageal artery, and its branches supplied the remainder of the bronchial tree. At 120 cmH2O pressure (n = 8), the bronchial branch contributed approximately 50% and the other two approximately 25% each of the total tracheobronchial blood flow. These three branches also supplied the visceral pleura. Additionally, several small vessels (rami pleurales pulmonales) originated from the esophageal branch (ramus esophagea) of the bronchoesophageal artery, traversed the pulmonary ligaments, and supplied the visceral pleura.