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 periodicals archive ?
The winking cover girl became its signature from its fifth issue onwards, when Terry mocked up a winking Princess Di.
This study also provides further evidence of the need, noted by others (Renzaglia & Everson, 1990; Winking et al.
And once he shook a few hands with his furry paw, he was presented with his Winking Bear mug filled with frosty A&W root beer for a victory toast.
Plus, I ended up with one of the rare Winking Bear Mugs, and that's what I was after.
Of the 100,000 A&W collector mugs produced for 2005, there are 984 in circulation that have a limited edition design: rather than having an image of a smiling Great Root Bear, these special mugs feature a winking Great Root Bear.
Jill said: "This winking shows that one is stepping into the realm of the forbidden.
This is one of the most ancient forms of winking as it used to tell people what to do.
The site includes additional information about the Winking Bear mug project, and also provides a couple of last-chance opportunities for collectors who think they've missed out.
In addition, the winner of the "What I'd Do to Get a Winking Bear Mug" essay contest will receive a set of 2005 mugs - both the collectible Smiling Bear mug and the limited-edition Winking Bear mug.