Eyelids: Functions, Layers, Innervation, Blood supply of eyelids
- Eyelid is a thin fold of skin that covers and protects an eye.
- Has thinnest skin of the whole body
- Has a row of eyelashes which serve to heighten the protection of the eye from dust and foreign debris, as well as from perspiration
- The skin is similar to areas elsewhere, but has more pigment cells.
- Superior and inferior tarsal plates are dense fibrous plates that give support and form to the eyelids. Tarsal glands produce oily secretions to prevent tears from leaking out, while the eyelids stay dry.
- Orbicularis oculi muscle contains both palpebral and orbital parts and acts to close the eyelids.
- The levator palpebrae superioris muscle retracts the eyelid to “open” the eye. This can be either voluntarily or involuntarily.
Layers of eyelids:
- Eyelid is made up of several layers
- Subcutaneous tissue
- Orbicularis oculi
- Orbital septum
- Tarsal plates
- Palpebral conjunctiva
Innervation of eyelids:
- Sensory nerve supply to the upper eyelids is from the infratrochlear, supratrochlear, supraorbital and the lacrimal nerves from the ophthalmic branch (V1) of the trigeminal nerve (CN V).
- The skin of the lower eyelid is supplied by branches of the infratrochlear at the medial angle, the rest is supplied by branches of the infraorbital nerve of the maxillary branch (V2) of the trigeminal nerve.
Supplied with blood by two arches on each upper and lower lid.The arches are formed by anastomoses of the lateral palpebral arteries and medial palpebral arteries, branching off from the lacrimal artery and ophthalmic artery, respectively.