Cranial Nerve 1:Olfactory Nerve

You have the olfactory receptors in the nasal mucosa that pierce the cribiriform plate in the ethmoid bone and passes to the olfactory bulb that synapses with neurones in the olfactory tract.

The olfactory tract ends deep in the temporal lobe and amygdaloid nucleus (part of the limbic system)


In an OSCE if they ask you the causes of anosmia, cribiform plate meningioma should NOT BE your first answer.

Differential Diagnosis of Anosmia

  1. Upper Respiratory Tract Infection- causing rhinitis and inflammation of the nasal mucosa
  2. Neuro-degenerative disorders- Parkinson’s disease being the most common
  3. Aneurysm- anterior communicating artery aneurysm
  4. Basal Skull Fracture of the ethmoid bone
  5. Tumours- Meningioma of the Cribiform Plate/Olfactory Groove