In the fetus, the thoracic ducts are a pair of vessels that ascend through the posterior mediastinum on each side of the descending thoracic aorta (Figs. 284 B and C). They continue through the superior mediastinum, on each side of the esophagus, to the root of the neck where each arches laterally, immediately behind the carotid sheath, and opens into the angle between the subclavian and the internal jugular veins. Because of pressure from the aorta, the left duct atrophies; the right persists, crosses to the left side and empties into the left subclavian vein. The disappearance and the persistence of the ductus is subject to great variation, so that any arrangement of anastomoses may result. Jossifow described some of these variations and the level of formation.
KeywordsInternal Jugular Vein Thoracic Duct Subclavian Vein Posterior Mediastinum Chylous Ascites
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