The trachea is a 10-12 cm long, relatively a movable pipe with a diameter of approximately 2 cm (Fig. 1 and 3).
The trachea has about 18 cartilage rings surrounding the trachea ensuring that the trachea at any given time is open. The trachea and the oesophagus are loosely held together (Fig. 3). The cartilage rings are c-shaped and are connected by smooth muscle on the posterior side of the tube (Fig. 3). This enables the body to regulate the diameter of the trachea and regulate the volume of air passing through the tube. In the trachea, there are mucus-producing cells with cilia. Cilia remove dust and particles from the trachea by moving towards the epiglottis so that the mucus with dust and particles enter the stomach during swallowing.