Conjunctiva
The conjunctiva or conjunctiva (synonym: tunica conjunctiva , from Latin tunica 'garment' and Latin coniungere 'connect') is a mucous membrane in the orbit (eye socket) in the anterior segment of the eye.
anatomy
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The conjunctiva begins at the edge of the eyelid and, as the tunica conjunctiva palpebrarum, covers the rear surface of the eyelids facing the eyeball . This mucous membrane coating acts like a soft wipe and spreads the tear fluid over the cornea when you blink without damaging it. At about the level of the base of the eyelids, the conjunctiva forms a flexible fold, runs forward and connects to the white skin of the eye ( sclera ). This section is called the tunica conjunctiva bulbi . The conjunctiva borders on the cornea, which in turn covers the pupil and iris. The conjunctiva forms the end of the eye socket to the environment.
The cavity enclosed by the conjunctiva is the conjunctival sac ( Saccus conjunctivae ). Its rear niche in the depths of the eye socket is called the conjunctival vault ( Fornix conjunctivae ). The ducts of the lacrimal gland ( glandula lacrimalis ) open here . The tear fluid is drained from the nasal corner of the eyelid through two tear points ( puncta lacrimalia ) towards the nose.
The conjunctiva forms an additional fold at the nasal corner of the eye, which is called the nictitating membrane ( Plica semilunaris conjunctivae , Membrana nicitans ) or "third eyelid" ( Palpebra tertia ). It is only very small in humans. In the other mammals , it is so large that it can lie in front of the entire eye. In many other vertebrates , e.g. B. sharks , reptiles and birds , it is transparent and can be folded over the eye like protective goggles.
In the mucous membrane of the conjunctiva, individual bundles of glands are embedded, which are called accessory lacrimal glands . The conjunctiva on the nasal corner of the eyelid is thickened to form the lacrimal caruncle ( Caruncula lacrimalis ).
The terminal branches of the blood vessels in the conjunctiva at the transition area between the sclera and the cornea are known as the peripheral loop network. This takes part in the care of the vascular cornea. If the cornea is inflamed, blood vessels can sprout into the cornea from this marginal loop network.
Clinical significance
The conjunctiva is examined at every general clinical examination. Since it is quite thin, well supplied with blood and unpigmented, changes in the blood can be easily recorded. So you can see a yellow coloration in jaundice (jaundice) and paleness in anemia or shock .
Inflammation of the conjunctiva is called conjunctivitis . It occurs in the event of local irritation (e.g. from foreign bodies ) and infections or in the course of some general infectious diseases (e.g. measles , distemper ). Solitary follicles in the conjunctiva can enlarge significantly in inflammation and then act like sandpaper and injure the cornea.
An under-bleeding of the conjunctiva is also called hyposphagma , but it does not cause any symptoms.
A conjunctival sample is a conjunctival provocation test in which conjunctivitis is provoked by the local application of an allergen solution.
literature
- Theodor Axenfeld (founder), Hans Pau (ed.): Textbook and atlas of ophthalmology. With the collaboration of Rudolf Sachsenweger a . a. 12th, completely revised edition. Gustav Fischer, Stuttgart a. a. 1980, ISBN 3-437-00255-4 .
- Gerhard K. Lang: Ophthalmology. Understand - Learn - Apply. 3rd, completely revised edition. Georg Thieme, Stuttgart a. a. 2004, ISBN 3-13-102833-5 .
Web links
Individual evidence
- ↑ conjunctiva on flexikon.doccheck.com
- ↑ Konjunktivalprobe , Roche Lexicon Medicine at www.gesundheit.de
- ↑ Provocation test , Roche Lexicon Medicine at www.gesundheit.de