The esophagus connects the pharynx to the stomach and is the narrowest part of the alimentary canal, with the exception of the vermiform appendix. This muscular tube extends from about the level of the lower border of the cricoid cartilage to the gastroesophageal junction. It can be divided into a cervical part, a thoracic part and an abdominal part, which is the shortest of the three parts.
Branches of the recurrent laryngeal nerve and postganglionic sympathetic fibers innervate the upper part of the esophagus. Below the level of the roots of the lung, the esophagus is surrounded by a wide meshed autonomic network known as the esophageal plexus and it supplies the lower esophagus. A branch of the vagus nerve (CN X), known as the anterior vagal trunk, also contributes to the esophageal plexus. Motor fibers which travel with the vagus nerve (CN X) supply the striated and smooth muscles of the walls of the esophagus.
Parasympathetic fibers that supply the abdominal esophagus come from the peri-esophageal thoracic plexus and from the anterior and posterior vagi. Sympathetic fibers that innervate the lower esophagus are derived from the fifth to twelfth thoracic spinal segments. These fibers are mainly distributed via the greater splanchnic nerve, the lesser splanchnic nerve and the coelic plexus.
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