Synonym
Medical: Sclera conjunctiva lat. : Conjunctiva
Definition
The conjunctiva is a part of the eye. As a mucous membrane, it lies against a part of the eyeball from the outside and against the eyelids from the inside. It can be changed in the course of diseases, this can be seen mainly by its colouring.
Anatomy
The conjunctiva consists of two parts. – The Conjunctiva tarsi (the tarsus is a part of the eyelids) covers as the outermost layer the inside of the upper and lower eyelid. – The Conjunctiva bulbi (the bulbus oculi is the eyeball) covers from the outside the part of the eyeball that is not covered by cornea, i.e. the upper and lower edge, where the sclera runs.
A multi-layered, non-cornifying squamous epithelium with mucus-producing goblet cells forms the basic structure of the conjunctiva. The change from the cornifying squamous epithelium of the skin (epidermis) to the non-cornifying squamous epithelium of the conjunctiva lies at the tarsi conjunctiva. At the fornix superior (upper bulge), which is located in the depth of the orbit, the tarsi conjunctiva merges from the eyelid into the bulbi conjunctiva of the eyeball.
The same happens at the inferior fornix, the lower bulge. In these areas the conjunctival sac is formed. The conjunctiva is transparent and very well supplied with blood.
It is firmly attached to the eyelids, while it is only loosely attached to the eyeball. The conjunctiva is richly sensitively innervated by small nerve fibres, which are all branches of the trigeminal nerve (5th cranial nerve): The arterial blood supply is through branches of the ophthalmic artery. Special structures of the conjunctiva of the eye:
- Frontal nerve.
- Lacrimal nerve
- Infraorbital nerve and
- Nasociliary nerve
- The so-called Plica semilunaris is a duplication of the mucous membrane, which lies softly, delicately and flexibly at the inner corner of the eye. – Caruncles are tissue elevations between the plica semilunaris and the inner corner of the eyelid. They consist of mucous membrane, skin parts and sebaceous glands.
- Everywhere in the epithelium of the conjunctiva, the mucosal goblet cells are present. – Processory lacrimal glands provide the aqueous component of the tear film and are located at the upper edge of the so-called tarsal plate of the upper eyelid and in the area of the fornices. The conjunctival sac is also known as the conjunctival sac and is an anatomical structure in every human being, located between the inner side of the upper eyelid and the eyeball as well as between the inner side of the lower eyelid and the eyeball.
Therefore, one can also distinguish between an upper and lower conjunctival sac. The conjunctival sac is formed by the fold of the different parts of the conjunctiva and the adjacent cornea and is also called Fornix conjunctivae in anatomy. This is where the conjunctivae that cover the posterior surface of the eyelids turn over to form the conjunctivae that cover the eyeball.
In a healthy person, there is always a certain amount of tear fluid in the conjunctivae, which keeps the surface moist and supple and protects against infection. This is also where medicines can be applied in ophthalmology. If the eye is diseased, pus or foreign bodies can be found here, for example, which disturb the normal function of the conjunctiva and eye. The conjunctiva consists of a multi-layered highly prismatic cylindrical epithelium in which goblet cells are embedded. The secretion of the goblet cells is part of the tear film.