CN1 Olfactory nerve

Question 1

What is cranial nerve 1?

Answer 1

Olfactory nerve

Question 2

What does the CN1 olfactory nerve innervate?

Answer 2

Olfactory mucosa in roof of nasal cavity

Question 3

What is the route of the CN1 olfactory nerve from its innervation to its origin?

Answer 3

Passes through cribriform foramina of ethmoid bone
forms olfactory bulb, which sits on top of the cribfirom plate of ethmoid bone
forms olfactory tracts, which runs to forebrain

Question 4

What is the function of the CN1 olfactory nerve?

Answer 4

Special sensory - olfaction, meaning sense of smell

Question 5

What is anosmia?

Answer 5

Loss of olfaction

Question 6

What are the causes of anosmia? Which is the most common cause?

Answer 6

Common cold - most common cause

Head injury
giving basilar skull fracture affecting cribriform
shearing of olfactory nerve

Intracranial tumour within anterior cranial fossa

Question 7

How is the function of the CN1 olfactory nerve tested?

Answer 7

Test smell of one nostril at a time

so that the other side cannot compensate