eyelids


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Eyelids

 

skin folds around the eyes in vertebrate animals and man. Eyelids serve to protect the eyeball from external injury, to moisten it with lachrymal fluid, and to remove foreign bodies from the eye. The majority of animals have paired (upper and lower), movable eyelids. In a number of sharks, amphibians, reptiles, birds, and some mammals, there is also a third movable eyelid—the nictitating membrane. In most mammals the third eyelid lacks musculature and is therefore immovable; in primates and in man it is reduced and forms a semilunar fold in the inner corner of the eye.

Eyelids in man consist of upper and lower movable skin folds that cover the eyeball when closed and circumscribe the eye aperture. The boundary of the upper lid is the recess between the orbit and the eyeball; the lower lid is separated from the cheek by a poorly defined furrow. The eyelids consist of skin, subcutaneous tissue, a muscle layer, a cartilaginous plate, and the conjunctiva. The skin of the eyelids is thin and turns into conjunctiva along the edges, where the eyelashes grow and the openings of the glands are located. The blood vessel network of the eyelids is well developed; sensory innervation is effected by branches of the trigeminal nerve; motor innervation is by the facial nerve.

Of greatest anthropological interest is the upper lid, the skin of which can form various types of folds—superior (suprapalpebral), median (palpebral), and inferior (tarsal). The last type of fold is more developed in the outer part of the eye and is manifested more strongly with age. Also distinguished is the Mongolian fold (epicanthic), which partially covers the lacrimal caruncle and is usually a continuation of the palpebral fold. The epicanthic fold is especially widespread among representatives of the Mongoloid race (up to 60 percent or more, especially frequent in women and children); it is absent among Caucasoids and Negroids (except for Bushmen).

REFERENCES

Roginskii, Ia. Ia., and M. G. Levin. Antropologiia, 2nd ed. Moscow, 1963.

eyelids

eyelids
Jet engine reverser or afterburner nozzle halves similar to an eyelid in appearance.
References in classic literature ?
She seemed to be holding them up in propitiation for her passionate desire to know and to think, which in the unfriendly mediums of Tipton and Freshitt had issued in crying and red eyelids.
It was the safe place for the battle that revived itself under Martin's eyelids.
Agnes saw that look; saw the eyelids of the living woman open slowly like the eyelids of the dead; saw her rise, as if in obedience to some silent command--and saw no more.
I have heard him talking of her in his sleep, and I have seen the tears on his eyelids.
Send me word by telegraph whether you would like Truffles again, or whether you would prefer something simpler and lighter--say that incomparable French dish, Pig's Eyelids and Tamarinds.
The East End of London, I read, or some one says; and first of all, under my eyelids, leap the visions of the shining pubs, and in my ears echo the calls for "two of bitter" and "three of Scotch.
Then she lowered her eyelids again, shutting all mysteriousness out of the situation except for the sobering memory of that glance, nightlike in the sunshine, expressively still in the brutal unrest of the street.
The man's purplish red face, his heavy eyelids, the nervous twitchings, all spoke of his addiction to drink.
Anna looked at her with drooping eyelids, and smiled, pressing her had.
In bed, she projected against her closed eyelids the few rich scenes of her mother that her child-memory retained.
What was Oliver's horror and alarm as he stood a few paces off, looking on with his eyelids as wide open as they would possibly go, to see the Dodger plunge his hand into the old gentleman's pocket, and draw from thence a handkerchief
Her lips and eyelids quivered; she opened her eyes full on his for an instant, like a lovely wild animal timid and struggling under caresses, and then turned sharp round toward home again.