Quick Facts
The skin of the eyelid is modified skin that makes up two-thirds of the thickness of the eyelid.
Related parts of the anatomy
Structure and/or Key Feature(s)
The anterior surface of the eyelids is covered by a modified layer of skin. It makes up about two thirds of the thickness of the eyelid, with the remaining, deeper part, composed of conjunctival mucosa. Between the skin and mucosa is a narrow “gray line” that marks the location of the ciliary bundle of the palpebral part of the orbicularis oculi muscle (the muscle of Riolan), a relatively avascular plane.
Sensations from the skin of the upper eyelid travel successively in the supraorbital nerve, the frontal nerve, and in ophthalmic division of the trigeminal nerve. It may also receive contributions from the lacrimal and supratrochlear branches of the frontal nerve and from infratrochlear branches of the nasociliary nerve. Sensation from the lower eyelid passes in the infraorbital branch of the maxillary nerve, the second division of the trigeminal nerve.
Anatomical Relations
The skin of the eyelid contains numerous folds. The superior palpebral furrow lies opposite the margin of the superior tarsus and is deepened when the eyelids are open. The less prominent inferior palpebral furrow also lies opposite its corresponding tarsal plate, which deepens during downward gaze.
The skin around the medial angle of the eye varies between populations. In Caucasians, the medial angle of the eye is completely exposed, while in Asians, the medial canthus is covered by the epicanthus (a semilunar fold of skin).
Function
The eyelids protect the eye from mechanical trauma and serve as a shield from excessive light. Periodic blinking helps prevent corneal drying and ulceration by maintaining a homogenous distribution of tear film over the cornea.
