What are the main functions of the eyelids?

The eyelids (palpebrae) primarily protect the eyes from injury, bright light, and foreign bodies. They also help moisten the cornea and maintain eye lubrication.

What are the five layers of the eyelid from superficial to deep?

From superficial to deep, the eyelid layers are: Skin (very thin), Superficial fascia (loose, lacks fat), Orbicularis oculi (closing muscle), Tarsal plate and palpebral fascia (fibrous stiffness), and Conjunctiva (inner lining).

What is the difference between a stye and a chalazion?

A stye (hordeolum) is an infection of the Zeis gland at the eyelash base, causing painful swelling. A chalazion is inflammation of the tarsal (Meibomian) gland, leading to swelling on the inner eyelid.

What is the palpebral fissure and what structures are visible through it?

The palpebral fissure is the elliptical opening between the eyelids. Visible structures include the lacus lacrimalis (medial space with caruncle), plica semilunaris (conjunctival fold), cornea and pupil, and sclera (white parts).

How are the eyelids supplied with blood and drained by lymphatics?

Arterial supply comes from medial palpebral branches of the ophthalmic artery and lateral palpebral branches of the lacrimal artery. Lymphatic drainage differs: medial halves drain to submandibular nodes, while lateral halves drain to preauricular nodes.

What causes ptosis (drooping eyelid)?

Ptosis is caused by paralysis of the levator palpebrae superioris muscle, often due to a lesion of the oculomotor nerve (cranial nerve III).

What are the glands found in the eyelids and their functions?

Eyelid glands include Tarsal (Meibomian) glands, which secrete oily fluid to reduce tear evaporation, and Ciliary glands (Glands of Zeis and Glands of Moll).

Eyelids – Layers, Tarsal Plates & Glands

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