- One of the two movable folds covering the front of the eyeball when closed; formed of a fibrous core (tarsal plate) and the palpebral portions of the orbicularis oculi muscle covered with skin on the superficial, anterior surface and lined with conjunctiva on the deep, posterior surface; rapid contraction of the contained muscle fibers produces blinking; they each have fixed (orbital) and free margins, the latter separated centrally by the palpebral fissure, united at the lateral and medial palpebral commissures, and bearing eyelashes, the openings of tarsal and ciliary glands and (medially) the lacrimal puncta. SYN: palpebra [TA], blepharon, lid.- inferior e. [TA] the inferior, smaller and less mobile of the two eyelids; a check ligament from the inferior rectus muscle extends into it, pulling the lid inferiorly when the gaze is directed downward. SYN: palpebra inferior [TA], lower e., lower lid.- lower e. inferior e..- superior e. [TA] the superior, larger and more mobile of the two eyelids which covers most of the anterior surface of the eyeball, including the cornea, when closed; a portion of the lacrimal gland and the aponeurosis of the levator palpebrae superioris muscle extend into it, the muscle opening the closed eye and providing additional elevation when the gaze is directed upward. SYN: palpebra superior [TA], upper e., upper lid.- third e. SYN: plica semilunaris of conjunctiva (2).- upper e. superior e..
* * *eye·lid 'ī-.lid n either of the movable lids of skin and muscle that can be closed over the eyeball called also palpebra
* * *n.the protective covering of the eye. Each eye has two eyelids consisting of skin, muscle, connective tissue (tarsus), and sebaceous glands (meibomian or tarsal glands). Each eyelid is lined with membrane (conjunctiva) and fringed with eyelashes. Stimulation of the pain receptors in the cornea causes the eyelids to close in a reflex action. Inflammation of a meibomian gland can result in a chalazion. Anatomical names: blepharon, palpebra.
* * *eye·lid (iґlid) either of the two movable folds (upper and lower) that protect the anterior surface of the eyeball; called also palpebra.
Medical dictionary. 2011.