The vagus nerve represents the nerve of the fourth and subsequent branchial arches. Caudally from the ganglion inferius, it descends along the internal carotid artery and the common carotid artery and arrives in the mediastinum via the superior thoracic aperture. The right nerve passes over the subclavian artery, and the left over the aortic arch and behind the root of the lungs. From that point on, both nerves are in close contact with the esophagus, forming the esophageal plexus. Terminal branches pass with the esophagus into the abdominal cavity via the diaphragmatic esophageal hiatus.