Cil (anatomie humaine)

An eyelash (also called lash) (Latin: Cilia) is one of the hairs that grows at the edges of the eyelids. The lashes grow outwards in up to six layers on the edges of the upper and lower eyelids. Eyelashes protect the eye from debris, dust, and small particles and perform some of the same functions as whiskers do on a cat or a mouse in the sense that they are sensitive to being touched, thus providing a warning that an object (such as an insect) is near the eye (which then closes reflexively). The eyelid margin from which lashes grow is among the most sensitive parts of the human body, with many nerve endings enveloping the lashes, giving it sensitivity to light touch, enabling it to trigger the blink reflex when touched. The word eyelash is a portmanteau derived from the prefix eye- referring to the eye which the lashes surround (by means of growing on the lids) and protects, and the suffix -lash, which can refer to a whip or the act of a stroke with a whip. This is in reference to both the individual lashes resembling a whip, and the action of blinking the eyes causing the lashes to move in a stroking or whipping motion. In humans, the eyelashes serve three main functions: Protect the eye from dust and debris by catching them before they can enter the eye Trigger the blink reflex in the case of a foreign body approaching the eye and touching the lashes Regulate or reduce evaporation of the tear film on the cornea The eyelashes of the human embryo develop from the ectoderm between the 22nd and 26th week of pregnancy. Eyelashes take about seven to eight weeks to grow back if pulled out, but constant pulling may lead to permanent damage. Their color may differ from that of the hair, although they tend to be dark on someone with dark hair and lighter on someone with light hair. Eyelash hair is not androgenic and is therefore not affected by puberty. Lash follicles do not have an arrector pili muscle associated with them, making the lashes static.