Ethmoidal nerve

The ethmoidal nerve is the largest division of the nasociliary nerve. It extends the curved trajectory of the nasociliary nerve to pass through the ethmoidal foramen. Once in the skull, it travels with the external ethmoidal artery along the lateral border of the ethmoidal fossae, then crosses the cribriform plate of the ethmoid bone via a special foramen to reach the bottom of the nasal cavity. It gives sensory branches to the nasal mucosa. It bifurcates to give the lateral and medial nasal branch, which extend in carnivores and pigs to give the external nasal branches.