The nasal cavity is divided in two by a vertical fin called the nasal septum. On the sides of the nasal cavity are three horizontal outgrowths called turbinates or conchae (singular "concha"). These turbinates disrupt the airflow, directing air toward the olfactory epithelium on the surface of the turbinates and the septum. The vomeronasal organ is located at the back of the septum and has a role in pheromone detection.
Cilia and mucus along the inside wall of the nasal cavity trap and remove dust and pathogens from the air as it flows through the nasal cavity. The cilia move the mucus down the nasal cavity to the pharynx, where it can be swallowed.
The nasal cavity is divided into two segments: the respiratory segment and the olfactory segment. The respiratory segment is lined with ciliated pseudostratified columnar epithelium (also called respiratory epithelium). The conchae are located in this region. The respiratory segment has a very vascularized lamina propria allowing the venous plexuses of the conchal mucosa to engorge with blood, restricting airflow and causing air to be directed to the other side of the nose. This cycle occurs approximately every 20-30 minutes. Nose bleeds in the inferior concha are common in this region. The olfactory segment is lined with a specialized type of pseudostratified columnar epithelium, known as olfactory epithelium, which contains receptors for the sense of the smell. This segment is located along the dorsal roof of the nasal cavity. Histological sections appear yellowish-brown due to the presence of lipofuscin pigments. Olfactory mucosal cell types include: bipolar neurons, supporting (sustentacular) cells, basal cells, and Bowman's glands. The axons of the bipolar neurons form the olfactory nerve (cranial nerve I) which enters the brain through the cribiform plate. Bowman's glands are serous glands in the lamina propria, whose secretions trap and dissolve odoriferous substances.the nasal cavity also can be called the nostril.
General sensory innervation is by branches of the trigeminal nerve (V1 & V2):
The entire nasal cavity is innervated by autonomic fibers. Sympathetic innervation to the blood vessels of the mucosa causes them to constrict, while parasympathetic innervation of the mucosa controls secretion by mucous glands.