Eyelid

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Eyelid Latin = Palpebra
(palpebra inferior, palpebra superior)
Eye makeup.jpg
Upper and lower eyelids
Gray'sp.1025
Arterylacrimal, superior palpebral, inferior palpebral
Nerveupper: infratrochlear, supratrochlear, supraorbital, lacrimal
lower: infratrochlear, branches of infraorbital
MeSH

[//www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Eyelids

  MeshNumber   = A01.456.505.420.504 Eyelids  
MeshNumber = A01.456.505.420.504]
 
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Eyelid Latin = Palpebra
(palpebra inferior, palpebra superior)
Eye makeup.jpg
Upper and lower eyelids
Gray'sp.1025
Arterylacrimal, superior palpebral, inferior palpebral
Nerveupper: infratrochlear, supratrochlear, supraorbital, lacrimal
lower: infratrochlear, branches of infraorbital
MeSH

[//www.nlm.nih.gov/cgi/mesh/2011/MB_cgi?mode=&term=Eyelids

  MeshNumber   = A01.456.505.420.504 Eyelids  
MeshNumber = A01.456.505.420.504]

An eyelid is a thin fold of skin that covers and protects the eye. With the exception of the prepuce and the labia minora, it has the thinnest skin of the whole body. The levator palpebrae superioris muscle retracts the eyelid to "open" the eye. This can be either voluntarily or involuntarily. The human eyelid features a row of eyelashes which serve to heighten the protection of the eye from dust and foreign debris, as well as from perspiration. "Palpebral" (and "blepharal") means relating to the eyelids. Its key function is to regularly spread the tears and other secretions on the eye surface to keep it moist, since the cornea must be continuously moist. They keep the eyes from drying out when asleep. Moreover, the blink reflex protects the eye from foreign bodies.

Structure[edit]

Layers[edit]

The eyelid is made up of several layers; from superficial to deep, these are: skin, subcutaneous tissue, orbicularis oculi, orbital septum and tarsal plates, and palpebral conjunctiva. The meibomian glands lie within the eyelid and secrete the lipid part of the tearfilm.

Skin[edit]

The skin is similar to areas elsewhere, but is relatively thin[1] and has more pigment cells. In diseased persons these may wander and cause a discoloration of the lids. It contains sweat glands and hairs, the latter becoming eyelashes as the border of the eyelid is met.[2] The skin of the eyelid contains the greatest concentration of sebaceous glands found anywhere in the body.[1]

Innervation[edit]

In humans, the 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.

Blood supply[edit]

In humans, the eyelids are supplied with blood by two arches on each upper and lower lid. The arches are formed by anastamoses of the lateral palpebral arteries and medial palpebral arteries, branching off from the lacrimal artery and ophthalmic artery, respectively.

Clinical significance[edit]

Any condition that affects the eyelid is called eyelid disorder. The most common eyelid disorders, their causes, symptoms and treatments are the following:

Surgery[edit]

The eyelid surgeries are called blepharoplasties and are performed either for medical reasons or to improve one's facial appearance.

Most of the cosmetic eyelid surgeries are aimed to enhance the look of the face and to boost one's self-confidence by restoring a youthful eyelid appearance. They are intended to remove fat and excess skin that may be found on the eyelids after a certain age. Cosmetic eyelid surgeries are mostly used to regain a younger and refreshed look but the costs are quite high, so not everyone can afford them.

Eyelid surgeries are also performed to improve one's peripheral vision or to treat chalazion, eyelid tumors, ptosis, trichiasis, and other eyelid-related conditions.

Eyelid surgeries are overall safe procedures but they carry certain risks since the area on which the operation is performed is so close to the eye.

Society and culture[edit]

Death[edit]

After death, it is common in many cultures to pull the eyelids of the deceased down to close the eyes. This is a typical part of the last offices.

See also[edit]

Eyelid affected by stye

Additional images[edit]

References[edit]

  1. ^ a b Goldman, Lee. Goldman's Cecil Medicine (24th ed. ed.). Philadelphia: Elsevier Saunders. p. 2426. ISBN 1437727883. 
  2. ^ "eye, human." Encyclopædia Britannica. Encyclopaedia Britannica Ultimate Reference Suite. Chicago: Encyclopædia Britannica, 2010.
  3. ^ "Facts About Blepharitis". Retrieved 2010-03-30. 
  4. ^ "Eyelid Disorders". Retrieved 2010-03-30. 
  5. ^ "Upper Eyelid Edema Treatment and Symptoms". Retrieved 2010-03-30. 
  6. ^ "Eyelid and Orbital Tumors". Retrieved 2010-03-30. [dead link]
  7. ^ "Eyelid twitch". Retrieved 2010-03-30. 
  8. ^ Taber's Cyclopedic Medical Dictionary, Edition 21, Page-6.

Sources[edit]