Final answer:
The corneal reflex is responsible for the rapid blinking response when an object like a piece of wood or stone contacts the eyelash or eyeball, involving the trigeminal and facial nerves triggering the orbicularis oculi muscle to contract quickly.
Step-by-step explanation:
The reaction experienced when an unexpected object like a piece of wood hits the eyelash or eyeball is largely due to the corneal reflex. This is a specialized protective response to stimulation of the cornea resulting in a rapid blink to help protect the eye. When the cornea or eyelashes are touched, it triggers a sensory response that travels through the trigeminal nerve. This sensory information is then conveyed to the brain which sends back a motor response through the facial nerve, causing the muscles around the eye, especially the orbicularis oculi, to contract and close the eyelid rapidly. The elaborate network of nerves and muscles responsible for this reflex action allows for the blink to occur extremely quickly, often in less than the blink of an eye, to prevent injury to the eyeball.
The fast reaction of blinking when an unexpected object hits the eyelash and eyeball is due to the corneal reflex. This reflex is a protective response to stimulate the cornea, causing the contraction of the orbicularis oculi muscle, resulting in blinking of the eye. The sensory information from the stimulated cornea travels through the trigeminal nerve or the optic nerve, depending on the stimulus, and the motor response travels through the facial nerve to close the eyelid.