The anterior ethmoidal nerve is a nerve which provides sensory branches to the nasal cavity.
The nerve is the continuation of the nasociliary nerve after it enters the anterior ethmoidal foramen into the anterior ethmoidal air cells. The nasociliary nerve arises from the Ophthalmic division of the Trigeminal nerve (CN V) within the orbit. The anterior ethmoidal nerve arises only after the nasociliary has given off its four branches
1) Ramus communicans to ciliary ganglion.
2) Long ciliary nerves
3) infratrochlear nerve
4) Posterior ethmoidal nerve.
After branching off of the nasociliary nerve, the anterior ethmoidal nerve enters the anterior ethmoidal foramen and send sensory fibers to the middle and anterior ethmoidal air cells. The anterior ethmoidal nerve then continues into the cranial cavity at the side of the cribiform plate of the ethmoid bone, sends sendory fibers to the meninges, and then enters the nasal cavity via the nasal slit. Within the nose, this nerve gives off sensory fibers to the anterior part of the nasal septum
The branches it gives rise to are called the internal and external nasal branches of the anterior ethmoidal nerve, and the external branch ultimately innervates skin on the lateral sides of the nose.