Plucking your eyebrows can trigger a sneeze by stimulating the trigeminal nerve.

The trigeminal nerve, also known as the fifth cranial nerve, is the largest and most complex of the cranial nerves. It is responsible for transmitting sensory information from the face, including the forehead, eyes, and nasal cavity, to the brain. This nerve splits into three main branches: the ophthalmic, maxillary, and mandibular nerves.When you pluck an eyebrow hair, you are specifically stimulating the ophthalmic branch. This branch provides sensory innervation to the skin of the upper face and the lining of the nose. Because these pathways are so closely interconnected, the brain can experience a phenomenon known as 'referred sensation' or 'cross-talk' between nerve fibers.The sudden stimulus from plucking can be misinterpreted by the medulla oblongata, which is the part of the brainstem that controls the sneeze reflex. The brain perceives the sharp sensation as an irritation inside the nasal passage rather than on the skin of the eyebrow. This triggers the involuntary expulsion of air to clear the non-existent irritant.Research into the trigeminal-cardiac reflex and similar neural pathways confirms that facial stimulation can have widespread autonomic effects. While not everyone experiences this 'pluck-sneeze' reflex, it is a well-documented example of how the body's sensory wiring can overlap. This reaction is similar to the photic sneeze reflex, where bright light stimulates the optic nerve and triggers a sneeze due to its proximity to the trigeminal nerve.