trachea /trā″kē·ə/ [Gk, tracheia, rough artery] , a nearly cylindric tube in the neck, composed of C-shaped cartilage and membrane and trachealis muscle, that extends from the larynx at the level of the sixth cervical vertebra to the fifth thoracic vertebra, where it divides into two bronchi. The trachea conveys air to the lungs. It is about 11 cm long and 2 cm wide. The ventral surface of the tube is covered in the neck by the isthmus of the thyroid gland and various other structures, such as the sternothyroideus and the sternohyoideus. Dorsally the trachea is in contact with the esophagus. Also called windpipe. See also primary bronchus.
