Paratarsium is a term derived from the Greek words "para" meaning beside or alongside, and "tarso" meaning the edge of an eyelid. It is primarily used in the field of ophthalmology to refer to a small, hair-like structure located on the inner surface of the upper or lower eyelids, near the edge. Also known as an eyelash or eyelash line, the paratarsium is responsible for the protection of the eye by preventing foreign substances, such as dust particles or insects, from entering the eye.
The paratarsium is composed of specialized cells that produce keratin, a tough protein that gives structure and strength to the eyelash. It is rooted within the eyelid, with one end firmly attached and the other extending away from the eyelid edge. The individual eyelashes that make up the paratarsium vary in length, thickness, and color among individuals, and serve aesthetic purposes as well.
The main function of the paratarsium is to act as a sensory organ, providing feedback to the body when something comes into contact with it. This triggers the eyelid to close reflexively to protect the eye. Additionally, the paratarsium participates in the spread of tears across the surface of the eye, aiding in the lubrication and maintenance of ocular moisture.
Overall, the paratarsium plays a crucial role in maintaining the health and well-being of the eye by acting as a physical barrier, contributing to sensory perception, and aiding in tear distribution.
