Overlay on top and bottomEyelidA layer of mucous membrane inside and in front of the eyeball.It is a transparent film formed by stratified columnar epithelium and a small amount of connective tissue.The eyelid conjunctiva is lining the inner surface of the eyelid, and the bulbar conjunctiva is sticking in front of the eyeball.The two parts are continuous with each other. When the eyelid is closed, the space enclosed by the conjunctiva is called the "conjunctival sac".It has the function of protecting and facilitating eye movement.The turning point between bulbar conjunctiva and eyelid conjunctiva is called fornix conjunctiva.The conjunctiva contains abundant blood vessels and nerve endings, and a small amount of mucus glands, which can secrete mucus and lubricate the eyeball to reduce the friction between the eyelid conjunctiva and the cornea.Chlamydia trachomatis mainly invades the eyelid conjunctiva and fornix conjunctiva.Both acute bacterial conjunctivitis and viral conjunctivitis are caused by bacteria and viruses infecting the conjunctiva, and both are infectious.
The conjunctiva is a transparent thin mucous membrane, soft, smooth and elastic, covering the inner surface of the eyelid (eyelid conjunctiva), part of the eyeball surface (bulbar conjunctiva), and the fold from the eyelid to the bulbar (fornix conjunctiva).These three parts of the conjunctiva form a saccular space with the eyelid fissure as the opening, which is called the conjunctival sac.
Classification of conjunctiva
Announce
edit
1) . Eyelid conjunctiva.
2) Bulbar conjunctiva: It covers the surface of the sclera at the front of the eyeball. It is loosely attached and can be moved. It is the thinnest and most transparent part of the conjunctiva.The bulbar conjunctiva is loosely connected with the sclera, and is fused with the bulbar fascia and sclera within 3mm near the corneal margin.There is a half moon shaped bulbar conjunctival fold on the temporal side of the lacrimal caruncle, called the half moon fold, which is equivalent to the third eyelid of lower animals.
3) The fornix conjunctiva is the fold part of the eyelid conjunctiva and bulbar conjunctiva moving mutually;Loose tissue is conducive to free eye movement.The upper fornix was entangled with the levator palpebrae superioris muscle fibers, and the lower fornix was integrated with the sheath fibers of the lower rectus muscle.
The conjunctiva is a mucous membrane, histologically composed of non keratinized squamous epithelium and goblet cells, with an epithelial layer and a lamina propria.The thickness and cell morphology of each part of the 2-5 layers of epithelium are different.The tarsal margin is flat epithelium, from the tarsal plate to the fornix, the cuboidal epithelium gradually transits to a cylindrical shape, the bulbar conjunctiva is flat, and the limbal cornea gradually transits to a stratified squamous epithelium, and then transits to the corneal epithelium.Goblet cells are single-cell mucus glands, which are mainly distributed in the epithelial layer of the eyelid conjunctiva and the fornix conjunctiva, and secrete mucus.The lamina propria contains blood vessels and lymphatic vessels, and is divided into glandular layer and fibrous layer.The glandular layer is thin, and the dome is well developed, containing Krause glands and Wolfring glands, which secrete serous fluid.This layer is composed of fine connective tissue network, in which there are a large number of lymphocytes, which are easy to form follicles in inflammation.The fibrous layer is interwoven by collagen fibers and elastic fibers, and the eyelid conjunctiva is lacking.
Conjunctival vessels come from the arch of eyelid artery and anterior ciliary artery.The arch of the palpebral artery passes through the tarsal plate and is distributed in the conjunctiva of the eyelid, the fornix conjunctiva and the bulbar conjunctiva 4mm away from the conjunctival edge of the talus. When it is congested, it is called conjunctival congestion.The anterior ciliary artery sends out small superior scleral branches at 3~5mm from the corneoscleral margin to form a vascular network around the corneal margin, which is distributed in the bulbar conjunctiva. When it is congested, it is called ciliary hyperemia.Two different types of hyperemia are of great significance in judging the location of eye lesions.
