In anatomy, a nasal concha (), plural conchae (), also called a nasal turbinate or turbinal, is a long, narrow, curled shelf of bone that protrudes into the breathing passage of the nose in humans and various animals. The conchae are shaped like an elongated seashell, which gave them their name (Latin concha from Greek κόγχη). A concha is any of the scrolled spongy bones of the nasal passages in vertebrates.In humans, the conchae divide the nasal airway into four groove-like air passages, and are responsible for forcing inhaled air to flow in a steady, regular pattern around the largest possible surface area of nasal mucosa. As a ciliated mucous membrane with shallow blood supply, the nasal mucosa cleans and warms the inhaled air in preparation for the lungs. A rapidly dilating arteriolar circulation to these bones may lead to a sharp increase in the pressure within, in response to acute cooling of the body core. The pain from this pressure is often referred to as "brain freeze", and is frequently associated with the rapid consumption of ice cream. The shallowness of the venous blood supply of the mucosa contributes to the ease with which nosebleed can occur. Structure
Conchae are composed of pseudostratified columnar, ciliated respiratory epithelium with a thick, vascular, and erectile glandular tissue layer. The conchae are located laterally in the nasal cavities, curling medially and downward into the nasal airway.
This secreted mucus covers the nasal cavities, and serves as a filter, by trapping air-borne particles larger than 2 to 3 micrometers. The respiratory epithelium also serves as a means of access for the lymphatic system, which protects the body from being infected by viruses or bacteria. Smell
The conchae provide, first and foremost, the humidity needed to preserve the delicate olfactory epithelium, which in turn is needed to keep the olfactory receptors healthy and alert. If the epithelial layer gets dry or irritated, it may cease to function. This is usually a temporary condition but, over time, may lead to chronic anosmia. The turbinates also increase the surface area of the inside of the nose, and, by directing and deflecting airflow across the maximum mucosal surface of the inner nose, they are able to propel the inspired air. This, coupled with the humidity and filtration provided by the conchae, helps to carry more scent molecules towards the higher, and very narrow regions of the nasal airways, where olfaction nerve receptors are located.The superior conchae completely cover and protect the nerve axons piercing through the cribriform plate (a porous bone plate that separates the nose from the brain) into the nose. Some areas of the middle conchae are also innervated by the olfactory bulb. All three pairs of conchae are innervated by pain and temperature receptors, via the trigeminal nerve (or, the fifth cranial nerve).