Eyelid | Surgical Anatomy Of The Eyelids

The eyelids are thin folds of skin, muscle, and fibrous tissue that serve to protect the delicate structures of the eye. The great mobility of the lids is possible because the skin is among the thinnest anywhere on the body. Fine hairs, visible only under magnification, are present on the eyelids. Beneath the skin lies loose areolar tissue that is capable of massive edematous distention. The orbicularis oculi muscle is adherent to the skin. It is innervated on its deep surface by the facial (VII) cranial nerve, and its function is to close the lids. It is divided into orbital, preseptal, and pretarsal divisions. The orbital portion, which functions primarily in forcible closure, is a circular muscle with no temporal insertion. The preseptal and pretarsal muscles have superficial and deep medial heads that participate in the lacrimal pump.

The lid margins are supported by the tarsi, rigid fibrous plates connected to the orbital rim by the medial and lateral canthal tendons. The orbital septum, which originates from the orbital rim, attaches to the levator aponeurosis, which then joins the tarsus. On the lower lid, it joins the inferior border of the tarsus. The septum is an important barrier between the eyelids and the orbit. Behind it lies the preaponeurotic fat pad, a helpful surgical landmark. An additional fat pad lies medially in the upper lid. The lower lid has two anatomically distinct fat pads beneath the orbital septum.

Deep to the fat lies the levator muscle complex—the principal retractor of the upper eyelid—and its equivalent, the capsulopalpebral fascia in the lower lid. The levator muscle originates in the apex of the orbit. As it enters the

eyelid, it forms an aponeurosis that attaches to the lower third of the superior tarsus. In the lower lid, the capsulopalpebral fascia originates from the inferior rectus muscle and inserts on the inferior border of the tarsus. It serves to retract the lower lid in downgaze. The superior and inferior tarsal muscles form the next layer, which is adherent to the conjunctiva. These sympathetic muscles are also lid retractors. Conjunctiva lines the inner surface of the lids. It is continuous with that of the eyeball and contains glands essential for lubrication of the cornea.

The upper lid is larger and more mobile than the lower. A deep crease usually present in the mid position of the upper lid in white populations represents an attachment of levator muscle fibers. The crease is much lower or is absent in the Asian eyelid. With age, the thin skin of the upper lid tends to hang over the lid crease and may touch the eyelashes. Aging also thins the orbital septum and reveals the underlying fat pads.

The lateral canthus is 1–2 mm higher than the medial. Because of loose tendinous insertion to the orbital rim, the lateral canthus is elevated slightly with up gaze.

Function Of The Eyelids : The eyelids are folds of muscular soft tissue that lie anterior to the eyeball and protect it from injury. Their shape is such that the eyeball is completely covered when they are closed. Strong mechanical, optical, and acoustic stimuli (such as a foreign body, blinding light, or sudden loud noise) “automatically” elicit an eye-closing reflex. The cornea is also protected by an additional upward movement of the eyeball (Bell’s phenomenon).Regular blinking (20–30 times/min) helps to uniformly distribute glandular secretions and tears over the conjunctiva and cornea, keeping them from drying out.

Inflammatory Conditions Of The Eyelids : Inflammation of the eyelids or inflammatory disease of the eyelids are...

-- Stye ( Hordeolum External ).

--Chalazion ( Meibomian Cyst ).

--Hordeolum Internal ( Acute Meibomitis ).

--Tarsitis.

--Herpes Zoster Ophthalmicus.

--Molluscum Contagiosum.

--Dermatitis with including eyelids.

Tumours Of The Eyelids : Tumours of the eyelids can be classified according to the structure of the origin into the following groups : Epithelial, Melanocytic, Vascular, Glandular and Neurogenic.

Epithelial Tumours Of The Eyelids : Squamous Cell Papilloma.

--Pseudocarcinomatous Hyperplasia.

--Keratocanthoma.

--Seborrheric Keratosis.

--Inverted Follicular Keratosis.

--Actinic Keratosis.

--Radiation Dermatosis.

--Xeroderma Pigmentosum.

--Basal Cell Carcinoma.

--Squamous Cell Carcinoma.

Melanocytic Tumours : Naevus Cell Tumours.

--Dermal Melanocytic Tumours.

--Epidermal Melanocytic Tumours.

--Malignant Melanoma.

--Dysplastic Naevus Syndrome.

Glandular Tumours : Benign Lesions.

--Sebaceous Gland Carcinoma ( Meibomian Cell Carcinoma )

Vascular Tumours : Capillary Haemangioma.

--Naevus Flammeus.

--Cavernous Haemangiomas.

--Lymphangioma.

--Glomus Tumour.

--Angiosarcoma.

Neurogenic Tumours : Neurofibromatosis ( Von Reckling Housen's Disease )

--Plexiform Neurofibroma.

--Diffuse Neurofibroma.

--Molluscum Fibrosum ( Fibroma Molluscum ).

Congenital Eyelids Anomalies : Epicanthal Folds.

--Telecanthus.

--Blepharophimosis.

--Euriblepharon.

--Colobamas of the eyelids.

--Ankyloblepharon.

Anomalies of the eyelids and cilia : Trichiasis ( Dystrichiasis )

--Districhiasis.

--Entropion.

--Ectropion.

Anomalies of the eyelids position : Ptosis.

Miscellaneous of the eyelids conditions : Xanthelasma.

--Blepharospasm.

--Blepharochalasis.

--Micropigmentation of the eyelids.

Read More About Eyelid Anatomy :

From Wikipedia : An eyelid is a thin fold of skin that covers and protects an 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. "Palpebral" (and "blepharo") means relating to the eyelids............................Read More

From American Family Physician : Anatomically complex, the eyelids consist of an anterior layer of skin and orbicularis oculi muscle, and a posterior layer of tarsus and conjunctiva. Contraction of the orbicularis muscle, innervated by the seventh cranial nerve, closes the eyelids. The levator muscle, innervated by the third cranial nerve, and the sympathetically innervated Müller's muscle raise the upper lid. The orbital septum, originating from the orbital rim, inserts into the upper lid just above the tarsal border and into the lower lid just below the tarsal border. The orbital septum limits the spread of infection and hemorrhage from the eyelid to the posterior orbital structures.............Read More

From Britannica Encyclopedia : Movable tissue, consisting primarily of skin and muscle, that shields and protects the eyeball from mechanical injury and helps to provide the moist chamber essential for the normal functioning of the conjunctiva and cornea. The conjunctiva is the mucous membrane that lines the eyelid and covers the visible portion of the eyeball except the cornea (the transparent part of the eyeball that covers the iris and the pupil). Each eyelid contains a fibrous plate, called a tarsus, that gives it structure and shape; muscles, which move the eyelids; and meibomian (or tarsal) glands, which secrete lubricating fluids. The lids are covered with skin, lined with mucous membrane, and bordered with a fringe of hairs, the eyelashes. The lids move through the action of a circular.............Read More

From Medicine Net.com : The lid or cover of the eye, a movable fold of skin and muscle that can be closed over the eyeball or opened at will. Each eye has an upper and a lower lid. An eyelid is also called a palpebra............Read More

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