The anterior ethmoidal nerve is a sensory nerve of the nasal region.
It supplies sensory innervation to the dura matter, nasal cavity, and part of the external nose.
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Course
The anterior ethmoidal nerve arises within the bony orbit as a terminal branch of the nasociliary nerve (itself a branch of the ophthalmic division of the trigeminal nerve).
It leaves the orbit and enters the cranial cavity via the anterior ethmoidal foramen. It is accompanied by the anterior ethmoidal artery and vein.
The anterior ethmoidal nerve then passes beneath the dura matter (to which it supplies anterior meningeal branches). It descends through a small foramen lateral to the crista galli of the ethmoid bone to enter the roof of the nasal cavity.
Now within the nasal cavity, it travels along the internal aspect of the nasal bone, giving rise to medial and lateral internal nasal branches.
It terminates as the external nasal nerve, which pierces the nasal cartilage to supply to the skin of the external nose.
Fig 1
The anterior ethmoidal nerve arises within the bony orbit as a terminal branch of the nasociliary nerve.
Sensory Supply
The anterior ethmoidal nerve supplies sensation to structures in the head via its branches:
- Anterior meningeal branches – supplies the dura mater associated with the anterior cranial fossa.
- Medial internal nasal branch – supplies the anterior and superior aspect of the nasal septum.
- Lateral internal nasal branch – supplies the anterior aspect of the lateral nasal wall.
- External nasal nerve – supplies the skin of the nasal dorsum and nasal tip.