Olfactory nerve (CN I)

Nervus olfactorius

NervousNervesHeadLeft and right

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What it is
The nerve of smell. About twenty tiny bundles (fila) rise from the roof of the nasal cavity through the sieve-like cribriform plate into the olfactory bulb, which lies under the frontal lobe; the olfactory tract then runs back to the brain.
Function
Carries smell from the olfactory mucosa to the olfactory cortex; it is the only sense that bypasses the thalamus.
Size
Bulb 10-12 x 4 mm; tract about 3.5 cm long
Clinical note
Fila are torn in head injuries that shear the cribriform plate, causing loss of smell (anosmia); a fracture there can also leak cerebrospinal fluid into the nose.

Nearby nervous structures Abducens nerve (CN VI), Amygdala, Globus pallidus, Oculomotor nerve (CN III), Olfactory tract root (CN I), Ophthalmic nerve (V1), Optic chiasm, Optic nerve (CN II), intracranial part, Putamen, Trochlear nerve (CN IV)