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 ?
In summary, external ophthalmomyiasis should be kept in mind in the differential diagnosis of patients presenting with conjunctivitis and a thorough slit-lamp examination including the inner eyelids should be conducted to ensure the diagnosis is not overlooked.
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.
It is alright to use these colours with a slight shimmer, even if you are using it on both the inner eyelids, as it helps to bring light to that area.
PALE INNER EYELIDS Possible cause: Anaemia If the inside of your lower eyelids look pale when pulled down, you may be anaemic - lacking iron, which helps makes red blood cells.
Some sharks do close the inner eyelids to protect their eyes when they are biting prey.