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.
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.
The internal nasal branches of the anterior ethmoidal nerve go to the mucous membrane of the front part of the septum (medial nasal branches) and lateral wall of the nasal cavity (lateral nasal branches).
The external nasal nerve are branches of the anterior ethmoidal nerve that pass through the ethmoidal groove of the nasal bone and supply the skin of the tip of the nose and ala.