Upper Respiratory Tract
Respiration begins at the nose where air is drawn in, filtered by the hairs in the nares, warmed by heat exchange with the blood vessels within the mucosa of the nasal cavities, and humidified by the fluid evaporating from mucus secreted by the lining mucosa in the nose.
Nasopharynx
From the nose, air moves towards the nasopharynx which runs from the base of the skull to the superior surface of the soft palate. It lies posterior to the nasal cavities and continues downwards posterior to the entrance of the laynx. The nasopharynx is lined by respiratory epithelium.
Larynx
Now, air passes from the nasopharynx to the larynx (also known as the voice box).
The larynx lies at the level of C3 - C6 cervical vertebrae, is composed of rings of cartilage and continues inferiorly as the trachea.