ABSTRACT
The conducting airway consists of the upper respiratory tract (nasal cavity, oral cavity, pharynx, larynx) and the lower respiratory tract (trachea, bronchi, bronchioles, alveolar ducts, alveolar sacs). The tracheobronchial tree is structurally subdivided into cartilaginous airways (conducting zone) and noncartilaginous airways (respiratory zone). The trachea is located in the middle of the conducting airway between the larynx and the main bronchi. In adults, the trachea is a semiflexible tube 1.5 to 2 cm wide and 10 to 13 cm long, attached to the lower portion of the larynx, approximately at the level of the sixth to seventh cervical vertebra and extending to the level of the fourth to fifth thoracic vertebra, where it bifurcates to form the two bronchi. 1 , 2 The infant trachea is 4 cm long and 0.36 cm in diameter.
