Plica semilunaris

Plica Semilunaris

The Plica semilunaris is a small, crescent-shaped fold of conjunctiva located at the inner corner of the human eye. It is a vestigial remnant of the nictitating membrane (third eyelid) present in other animals. The plica semilunaris contributes to the maintenance of the tear film on the eye's surface and facilitates eye movement.

Anatomy

The plica semilunaris is composed of fibrous tissue covered by conjunctival epithelium. It is located medially in the eye, adjacent to the caruncle. The plica semilunaris allows for greater rotation of the globe, and acts as a channel for the tear film to spread over the surface of the eye.

Function

The primary function of the plica semilunaris is to aid in the movement of the eye. It allows for horizontal movement, enabling the eye to move more freely and with a wider range of motion. Additionally, the plica semilunaris helps in the distribution of tears across the eye's surface, maintaining the ocular surface's moisture and protecting it from dust and debris.

Clinical Significance

In some cases, the plica semilunaris may become inflamed or infected, a condition known as Plica Syndrome. This can result in discomfort, redness, and swelling in the inner corner of the eye. Treatment typically involves the use of topical antibiotics or steroids.

See Also

• Conjunctiva
• Nictitating membrane
• Plica Syndrome