lid (redirected from keep the lid on)

lid.

See eyelid.

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lid

see eyelid.

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eyelids

A pair of movable folds of skin which act as protective coverings of the eye. The upper eyelid extends downward from the eyebrow and is the more moveable of the two. When the eye is open and looking straight ahead, it just covers the upper part of the cornea; when it is closed, it covers the whole cornea. The lower eyelid reaches just below the cornea when the eye is open and rises only slightly when it shuts. Each eyelid consists of the following layers, starting anteriorly: (1) skin, (2) a layer of subcutaneous connective tissue, (3) a layer of striated muscle fibres of the orbicularis muscle, (4) a layer of submuscular connective tissue, (5) a fibrous layer, including the tarsal plates, (6) a layer of smooth muscle, (7) the palpebral conjunctiva. Syn. blephara; lids; palpebrae. See ablephary; blepharitis; ciliosis; ectropion; entropion; epicanthus; lid eversion; eyelid lamella; lagophthalmos; palpebral ligament; myokymia; orbital septum; phthiriasis; Cogan's lid twitch sign; Collier's sign; Dalrymple's sign; inferior palpebral sulcus; superior palpebral sulcus; tarsorrhaphy; tarsus; xanthelasma.
eyelids lamella The eyelid is sometimes conceptualized as consisting of an anterior and a posterior lamella. The anterior lamella consists of the skin, the layer of subcutaneous connective tissue and the layer of striated muscle fibres of the orbicularis muscle. The posterior lamella consists of the tarsal plates, a layer of smooth muscle (Müller's palpebral muscle), and the palpebral conjunctiva.
eyelids retractor muscles The eyelid muscles that open the palpebral aperture. The upper eyelid is elevated by the levator palpebrae superioris muscle and the superior tarsal muscle (of Müller) and the lower eyelid is depressed by the inferior tarsal muscle (of Müller).