The esophagus and trachea derive from the foregut during the 4th week of development and is constructed as a part of the gut: longitudinal and circular muscle bundles are connected to a functional system together with collagen and elastic fibers. The action of the cricopharyngeal "pinch-cock" is pronounced in the newborn. In the region of the upper orifice ganglion cells are absent and venous vessels are oriented in a longitudinal direction. The myoelastic fiber system is in the lower part of the esophagus arranged as a stretching system, and the esophagus becomes longer and narrower by traction. The blood vessels derive from the thyroid arteries, the aorta, the bronchial arteries, the left gastric artery and the left inferior phrenic artery. Poor zones of vascularity are in the middle of the ventral and dorsal plane.