Which branch of CN V1 supplies the most medial portion of the upper eyelid and lower eyelids?

• A. Lacrimal nerve
• B. Supraorbital nerve
• C. Supratrochlear nerve
• D. Infratrochlear nerve

Answer: (D)

The medial eyelid region is supplied by the infratrochlear nerve, a branch of the nasociliary nerve from CN V1. This nerve travels along the medial orbital wall toward the medial canthus and provides sensation to the skin of the medial canthus and adjacent portions of both the upper and lower eyelids. Other branches like the lacrimal nerve tend to supply the lateral upper eyelid and lacrimal gland, while the supraorbital and supratrochlear nerves cover more of the forehead and the more central to superior aspects of the upper eyelid. Since the infratrochlear nerve specifically covers the most medial portion of the eyelids, it best matches the region described.