powiek

Powiek, or eyelids, are paired folds of skin and tissue that cover the front of the eye. Their primary roles are to protect the ocular surface from mechanical injury, dust and light, and to help spread and maintain the tear film across the cornea through blinking. Each eyelid contains an external skin surface, a dense connective tissue framework called the tarsal plate, and an inner palpebral conjunctiva. The upper lid is moved mainly by the levator palpebrae superioris muscle with its aponeurosis, while the orbicularis oculi muscle closes the lids.

Anatomically, the eyelid margin houses eyelashes and several glands that contribute to tear film stability. Meibomian glands within the tarsal plates secrete lipids that form the outer tear film layer and reduce evaporation. The glands of Zeis and Moll, located near the lash line, contribute to oil and sweat components of the lid margin. The palpebral conjunctiva lines the inner surface of the lids, and the lids work with the lacrimal apparatus to regulate tear production and drainage via the medial canthus and puncta.

Nerve and blood supply support lid function. Motor control is provided mainly by the facial nerve (cranial nerve VII) for eyelid closure and the oculomotor system for lid elevation. Sensation is via branches of the trigeminal nerve (cranial nerve V). Clinically, powiek can be affected by conditions such as blepharitis (inflammation of the eyelids), styes (hordeolums), chalazia, and ptosis, which can impact protection and tear film dynamics. Blepharoplasty or other lid procedures may be used to address functional or cosmetic concerns.