The nasal cavity is the inside of the nose and is the uppermost part of the respiratory system. It has several functions, including:

• Warming and humidifying the inspired air: The nasal cavity has an abundant supply of vasculature to aid in functions of warming and humidifying inhaled air.

• Filtering the inspired air: The nasal cavity removes minute airborne particles, pathogens, and particulate matter from the inspired air. There are also little hairs that help filter the air you breathe in, blocking dirt and dust from getting into your lungs.

• Olfaction: The nasal cavity is responsible for the sense of smell.

• Draining and clearing the paranasal sinuses and lacrimal ducts: The nasal cavity facilitates drainage for the secretions from the adjacent paranasal sinuses.

The nasal cavity is divided into two separate cavities by the septum and kept patent by a bone and cartilaginous framework. Each cavity consists of a roof, floor, medial wall, and lateral wall. Within each cavity are three regions: nasal vestibule, respiratory region, and olfactory region.