Structure and Origin
- The anterior ethmoidal nerve is a terminal branch of the nasociliary nerve, which is a branch of the ophthalmic nerve (CN V).
- It branches near the medial wall of the orbit.
- It passes through the anterior ethmoidal canal alongside the anterior ethmoidal artery and vein.
- It emerges in the anterior cranial fossa through the anterior ethmoidal foramen.
- Within the cranial cavity, it passes along a groove upon the superior surface of the cribriform plate and descends through an aperture situated lateral to the crista galli to reach the nasal cavity.

Course
- The anterior ethmoidal nerve passes through the anterior ethmoidal canal alongside the anterior ethmoidal artery and vein.
- It emerges in the anterior cranial fossa through the anterior ethmoidal foramen.
- Within the cranial cavity, it passes along a groove upon the superior surface of the cribriform plate.
- It descends through an aperture situated lateral to the crista galli to reach the nasal cavity.
- In the nasal cavity, it passes along a groove upon the internal aspect of the nasal bone and issues the medial and lateral internal nasal branches.

Distribution
- Within the anterior cranial fossa, the anterior ethmoidal nerve provides sensory fibers to the meninges for sensory innervation.
- Its medial internal nasal branch innervates the superior and anterior portions of the nasal septum.
- Its lateral internal nasal branch innervates the anterior portion of the lateral nasal wall.
- It gives off branches to the roof of the nasal cavity and bifurcates into a lateral internal nasal branch and medial internal nasal branch.
- Its terminal branch, the external nasal nerve, innervates the skin of the nose between the nasal bones superiorly and the tip of the nose inferiorly.

Function
- The anterior ethmoidal nerve is involved in the diving reflex.

Relationship with other nerves
- The anterior ethmoidal nerve is a branch of the nasociliary nerve, which is a branch of the ophthalmic nerve (CN V).
- The ophthalmic nerve is a branch of the trigeminal nerve (CN V).

Anterior ethmoidal nerve (Wikipedia)

The anterior ethmoidal nerve is a nerve of the head. It is a branch of the nasociliary nerve (itself a branch of the ophthalmic nerve (V₁)). It arises in the orbit, and enters first the cranial cavity and then the nasal cavity. It provides sensory innervation to part of the meninges, parts of the nasal cavity, and part of the skin of the nose.

Anterior ethmoidal nerve
The ophthalmic artery and its branches. (Nerve not pictured, but location is similar to artery.)
Details
From	nasociliary nerve
Identifiers
Latin	nervus ethmoidalis anterior
TA98	A14.2.01.030
TA2	6208
FMA	52675
Anatomical terms of neuroanatomy [edit on Wikidata]