Winking


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Winking

 

(also nictitation), a protective unconditioned reflex (or a conditioned reflex formed on its basis) in response to stimulation of the sensory branches of the trigeminal nerve in the cornea or conjunctiva of the eye, in the skin of the eyelids, and in the eyelashes, as well as in response to light stimulation. The closing of the palpebral fissure before entry of a harmful agent into the eye is an important biological adaptation. During winking the eyeball is washed by lacrimal fluid, which helps remove foreign bodies. Winking is effected primarily by contraction of the orbital muscle, which is innervated by fibers of the facial nerve. In response to stimulation of the trigeminal nerve, the reflex arc is closed in the region of the medulla oblongata. Absence of winking is observed when the facial nerve is paralyzed or when the trigeminal nerve is damaged. Intensification and increase in the frequency of winking, often accompanied by tearing and photophobia, are observed with conjunctivitis.

References in classic literature ?
Feeling convinced that she was in imminent danger of becoming downright drunk if I gave her another glass, I kept my hand on the bottle, and forthwith told my story over again in a very abridged and unceremonious form, and without allowing her one moment of leisure for comment on my narrative, whether it might be of the weeping, winking, drinking, groaning, or ejaculating kind.
While they were winking the workman disappeared, tools and all.
Mind you write us every week at the very least," said Felicity, winking furiously.
There they sat winking, while the summer-house was cleared of the rank growth that had choked it up, while the rotten wood-work was renewed, while all the murky place was purified with air and light.
With that I brought him in and set him down to my own place, where he fell-to greedily on the remains of breakfast, winking to me between whiles, and making many faces, which I think the poor soul considered manly.
His big, prominent eyes were not well adapted to winking.
At his feet, sat a white-coated, red-eyed dog; who occupied himself, alternately, in winking at his master with both eyes at the same time; and in licking a large, fresh cut on one side of his mouth, which appeared to be the result of some recent conflict.
But, so much more powerful were the frailties of Sloppy's form than the strongest resources of tailoring science, that he now stood before the Council, a perfect Argus in the way of buttons: shining and winking and gleaming and twinkling out of a hundred of those eyes of bright metal, at the dazzled spectators.
Here he went through the not very difficult process of winking upon the company with his solitary eye, to the enthusiastic delight of an elderly personage with a dirty face and a clay pipe.