Nasal reflexes

Nose is endowed with various reflexes. These reflexes are aimed at protecting the lower airway from insults,while there are other reflexes that coordinate with physiological functions ofother systems.

The following are the various reflexes involving the nose:

Naso nasal reflex:

This reflex is also known as sneezing. This is purely a protective reflex aiming to protect the lower airways from the deleterious effects of substances mixed with the inspired air. This reflex is mediated by the trigeminal and vagal nerves. This reflex may occur due to a variety of stimuli like inhalation of fumes / noxious substances. This reflex is caused by deep inspiration followed by forced expiration against closed glottis.

Nasobronchial reflex:

This reflex is also known as nasopulmonary reflex / nasolaryngeal reflex. This is an ipsilateral reflex again mediated by trigeminal and vagal nerves. In this reflex nasal stimulation may cause reduction of breathing even cessation (apnoea). This is caused due to constriction of bronchioles and laryngeal inlet. This reflex is more predominant in elderly. This reflex was demonstrated by increased levels of carbon dioxide in blood following packing of nasal cavities. Hence care should be taken while packing the nasal cavities in elderly. This is more common when Bellocq type nasal packs are used.

Corporonasal reflex:

This reflex is also known as the classic diving reflex. This reflex is caused when face or upper part of the body comes into contact with cold water. This causes cessation of respiration. This reflex also causes bradycardia and contraction of sub mucosal blood vessels under the nasal mucosa.

Nasocardiac reflex:

In this reflex strong stimulation of nasal mucosa causes bradycardia and reduction in cardiac output and lowering of blood pressure.

Nasovascular reflex:

In this reflex stimulation of nasal mucosa causes peripheral vasoconstriction.

Genitonasal reflex:

Sexual arousal / orgasm causes swelling of nasal mucosa, especially the turbinates.

Gastronasal reflex:

Strong gastric stimulation causesincreased nasal secretion and congestion of nasal mucosa.