[Sensitive innervation of the nasal mucosa: current concepts]

Sensitive innervation of the nasal fossae by the trigeminal nerves is not a simple passive system of information transmission, but also plays a considerable role in nasal physiology. An antidromic transmission mechanism is in fact added to the conventional centripetal transmission, leading to the release of neurotransmitters (P-substance and C.G.R.P.) at the level of the neuronasal nerve endings. These substances can cause inflammation and vasodilatation (sub-mucosal and perivascular) in certain sites of the 5th nerve, and stimulate the second parasympathetic neurone at the level of the sphenopalatine ganglion. Such phenomena, when they extend beyond physiology, can be the source of local pathology (rhinitis) or loco-regional pathology (headaches).