nictitating membrane

(redirected from Inner eyelid)
Also found in: Dictionary, Thesaurus, Medical.

nictitating membrane

(in reptiles, birds, and some mammals) a thin fold of skin beneath the eyelid that can be drawn across the eye

Nictitating Membrane

 

a third eyelid, located in the inner corner of the eye in some Euselachiae (fishes) and the majority of terrestrial vertebrates. The nictitating membrane is formed from a fold of the conjunctiva and is located behind the upper and lower eyelids. In terrestrial vertebrates, a transparent nictitating membrane periodically covers the cornea to clean and moisten it. Nictitating membranes are most highly developed in reptiles and birds. Among mammals, a third eyelid is absent in Echidna and Cetacea; apes and humans have rudimentary nictitating membranes in the form of semilunar folds.

nictitating membrane

[′nik·ə‚tād·iŋ ′mem‚brān]
(vertebrate zoology)
A membrane of the inner angle of the eye or below the eyelid in many vertebrates, and capable of extending over the eyeball.
References in periodicals archive ?
Create a more dramatic effect by using the same pencil to draw a line along the inner eyelid.
On dark skin, check on lighter parts of the body; for example, the inner eyelids or fingertips.
They don't blink, but they can close their inner eyelids to protect their eyes when they are biting prey.
Ferric sulfate solution can be an irritant to the mucous membranes, respiratory tract and lung tissue, and can cause burns to the skin or the inner eyelids.