CN I: Olfactory nerve

Authors

Affiliations

Nate Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

• Type: Sensory
• Function: Sense of smell
• Dysfunction: Anosmia (loss of smell)

Central Olfactory Structures

Pathway:

First order neurons:

1. Smell is detected by specialized chemoreceptors on bipolar primary sensory neurons found in the olfactory neuroepithelium¹
2. Olfactory nerve (made up of axons combined with other receptor cell axons)¹
3. Pass through Cribriform plate of Ethmoid bone¹
4. Terminate on the olfactory bulb (main relay station of olfactory pathway)¹

Second order neurons:

1. Olfactory tract
2. Split: Medial & Lateral striae
   1. Medial Stria: Projects to subcallosal gyrus
   2. Lateral Stria: continues on to Parahippocampal gyrus

Relevant Structures

The olfactory nerve does not have peripheral ganglia

Olfactory cortex: no single structure - Piriform cortex: - Located: Below lateral olfactory stria - Function: Olfactory processing - Amygdala: - Located: Anterior to Temporal/Inferior horn of Lateral Ventricle - Function: Emotion & Fear - Entorhinal cortex: - Location: Anterior part of Parahippocampal gyrus - Function: Formation of Memory

Pupillary light reflex

CN2 is involved in the pupillary light reflex

Dysfunction

• Anosmia

References

1.

Blumenfeld H. Neuroanatomy Through Clinical Cases. 3rd ed. Oxford university press; 2022.