When you sneeze, the spray of mucus and saliva can reach a speed of 100 mph. So some people have come to believe that it is impossible to sneeze with your eyes open because they will pop out or bulge out of your head. This is actually not true. The eye has muscles including the medial and lateral rectus, superior and inferior oblique, and superior and inferior rectus to keep the eye in place. The optic nerve and the conjunctiva, the covering of your eye that is a squamous epithelium layer also plays a role in making sure your eyes don’t leave its sockets. These structures keep the eye from falling out when you sneeze. So then why do our eyes close when we sneeze? Well, there is no actual answer. It’s just an involuntary reaction that your eyelid muscles contract when you sneeze causing them to close.
If you don’t believe me, here is a video of Adam from the show Mythbusters sneezing with his eyes open.
Sneezing is a reflexive act that happens when your nasal passageways are irritated by something. Sneezing involves a reflex arc, which is the circuit traveled by impulses producing a reflex action – from the receptor organ, through the afferent nerve (sensory nerve), nerve center, efferent nerve (motor nerve), to the effector (another organ, hormone, etc.). Here are the steps:
1. An irritant is detected by nerve endings (receptors) in your nasal passageways; this irritant could be anything from a smell, dust, viruses that attack mucosa membranes, and so on.
2. Nerves carry these impulses to sneezing center in your brain stem.
3. Then the sneezing center sends the instructions down your facial nerves and nerves that lead to your lungs and diaphragm.
4. This causes your eyes to start to water and your nasal passageways to secrete fluid. This also causes you to take in a deep breath, caused by an abrupt movement of your diaphragm.
5. Next, the diaphragm and your chest muscles contract, which causes the air to leave your nose and mouth suddenly and fast.