The supraorbital nerve block provides sensory innervation to which portion of the upper eyelid?

• A. Lateral third
• B. Medial two-thirds
• C. Central one-third
• D. Entire eyelid

Answer: (B)

Nerve distribution to the eyelids determines what a targeted nerve block will numb. The supraorbital nerve, a branch of the frontal nerve from the ophthalmic division, travels along the upper eyelid margin and sends branches that supply sensation predominantly to the medial portion of the upper lid. Therefore, when you perform a supraorbital nerve block, you mainly desensitize the medial two-thirds of the upper eyelid. The lateral portion of the lid is supplied by other nerves, so it would not be reliably numb with this block alone. If complete eyelid anesthesia were needed, additional blocks targeting those other nerves would be required.