The trachea and esophagus are located in relation to each other in position with the trachea in front of the esophagus, separated by the epiglottis cartilage. The trachea and esophagus are located in the middle of the neck, one in front of the other, and in position, the trachea is in front of the esophagus, separated by the epiglottis cartilage. Usually the trachea is located anterior to the middle esophagus in the neck, and it is a lumen composed of cartilage, muscular mucosa, and connective tissue. The upper end usually begins at the lower edge of the cricoid cartilage, which corresponds to the plane of the sixth cervical vertebra, thus entering the thoracic cavity. The lower end corresponds to the upper edge of the fifth cervical vertebra and divides into the right and left main bronchi. The esophagus is composed of muscle and mucous membrane and begins at the lower edge of the cricoid muscle and descends to the cardia. In general, the entrance to the esophagus in adults corresponds to the plane of the sixth cervical vertebra, while the cardia correspond to the planes of the tenth and eleventh thoracic vertebrae, and is approximately 23 to 25 centimeters in length. The wall of the esophagus is thin, about 3 to 4 millimeters thick in adults.