ABSTRACT
The respiratory passageway consists of the nose and nares, nasal cavity, pharynx, larynx, trachea, bronchi, and lungs. The middle portion of the nasal cavity is its largest region, and is sometimes referred to as its “respiratory region”. The nose is the short relatively narrow portion of the airway extending from the exterior to the more capacious space of the nasal cavity. The skin of the planum nasale is thickened and tough, presenting numerous small, raised, circular nodules on its rostral surface. The incisive duct is a narrow tubular passage between the rostral parts of the nasal and oral cavities. The space within the nasal cavity houses the conchae or turbinates, which are intricate and delicate scroll work of bone. The pharynx is a soft tissue-walled tubular region leading from the caudal end of the nasal and oral cavities to the cranial end of the larynx and esophagus.
