Eyelids & Conjunctiva: Structure & Functions

Flashcards covering the anatomical structures, muscle types, nerve supplies, and histological features of the eyelids and conjunctiva based on the ABDO College lecture notes.

Orbicularis Oculi Muscle

A flat, oval sheet of striated muscle consisting of orbital and palpebral portions; responsible for reflex voluntary blinking and forcible lid closure, innervated by the Facial Nerve ($CNVII$).

Levator Palpebrae Superioris

A striated muscle that originates at the apex of the orbit and elevates the upper eyelid; it is innervated by the Oculomotor Nerve ($CNIII$).

Muscle of Riolan

Also known as the ciliary bundle, this striated muscle is a portion of the pretarsal orbicularis oculi located at the lash follicle; it maintains lid tension against the globe.

Muller’s Muscle

A smooth muscle that inserts into the superior border of the tarsal plate and controls the position of the lids; it is supplied by sympathetic nerves.

Tarsal Plate

A fibrous layer that, along with the orbital septum, forms the structural framework and bulk thickness of the eyelid.

Marginal Conjunctiva

The region commencing at the Meibomian glands with $5$ to $6$ layers of cells and a square posterior edge that allows the lids to sweep the tear film across the cornea.

Tarsal Conjunctiva

A highly vascular region where the epithelium thins to a double layer of cells (columnar superficial and flatter deep) behind the tarsal plate.

Fornices

The folding junctions between the bulbar and palpebral regions of the conjunctiva; they contain the highest density of goblet cells and the thickest stroma.

Bulbar Conjunctiva

A thin, translucent region with stratified columnar cells loosely attached to the sclera and fascia; it is continuous with the corneal epithelium.

Goblet Cells

Cells found in the conjunctiva, most densely in the fornices, that produce mucin to act as a wetting agent for the tear film.

Substantia Propria

The lower connective tissue layer of the conjunctiva, also referred to as the stroma, which contains capillaries, lymphatic vessels, and accessory lacrimal glands.

Palisades of Vogt

Radial epithelial folds found in the bulbar region close to the limbus.

Rete Pegs

Folds in the stroma located close to the limbus in the bulbar conjunctival region.

Glands of Krause and Wolfring

Accessory lacrimal glands located within the stroma of the palpebral conjunctiva that produce the aqueous phase of the tear film.

Ophthalmic Artery

The primary source from which the blood supply of the conjunctiva is derived.

Nasociliary Nerve

The nerve whose ciliary branches receive sensory information from the bulbar region of the conjunctiva around the limbus.

Aponeurosis

The flat striated sheet or distal tendon of the levator palpebrae superioris which divides the lacrimal gland and attaches to the orbital walls.

Glands of Moll and Zeis

Glands located near the eyelashes; Zeis glands are associated with the hair follicle and Moll glands are modified sweat glands.

Meibomian Glands

Tarsal glands located within the tarsal plate that contribute to the lipid layer of the tear film.

Immunoglobin A

An antibacterial factor produced in the stroma of the conjunctiva to provide protection against microbial infection.