Olfactory nerve

Last edit by Alaric Steinmetz on

Synonyms: Riechnerv

The olfactory nerve is the first cranial nerve and is responsible for the sense of smell. It consists of the Fila olfactoria, which are fine nerve fibers serving olfactory perception[^1].

Anatomy

The Fila olfactoria are about 20-25 small bundles of unmyelinated nerve fibers. They transmit the electrical impulses from the olfactory cells of the olfactory region of the nasal mucosa through the cribriform plate of the ethmoid bone and terminate mainly at the dendrites of mitral cells in the olfactory bulb. The impulses are then relayed via the olfactory tract in the olfactory peduncle to the olfactory trigone on the basal surface of the brain and from there to the primary olfactory cortex.

Clinical Testing

The function of the olfactory nerve can be tested through an olfactory test.

Figure

Nervus olfactorius
Schematische Abbildung des Nervus olfactorius. Abbildung adaptiert von Patrick J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist. https://creativecommons.org/licenses/by/2.5/

Pathology

In patients with a traumatic brain injury, there can be an avulsion of the Fila olfactoria, leading to loss (anosmia) or reduction (hyposmia) of the sense of smell. Similarly, meningiomas may arise in the area of the olfactory bulb (olfactory meningiomas), which may also lead to a restriction of the sense of smell.