Nasal and oral cavities
Video Tour	Rotateable picture
Nasal cavity and pharynx From labbook P 169. Air enters the nasal cavity through the external nares (nostrils). In the nasal cavity, inhaled air encounters three nasal concha( superior, middle, and inferior). These structures disrupt the flow of air and cause it to move around the nasal cavity where the air is warmed and humidified by mucus produced by the epithelium and the 4 para nasal sinuses. The mucus, which is produced by goblet cells, also traps small particles and prevents them from entering the respiratory track. Air exits the nasal cavity through the internal nares through a "tube" called the choanae which leads to the first part of the pharynx; the nasopharynx. You will notice on the picture the eustachian tube enters from the middle ear here. The pharyngeal tonsil is also here. The nasopharynx joins the oropharynx which is the section of the pharynx behind the mouth. It has the lingual and palatine tonsils. The third section, the laryngopharynx, is where the respiratory tract splits from the digestive tract and enters the glottis. You can see the start of the larynx and the esophagus