Conjunctiva
| Conjunctiva | |
|---|---|
 The upper half of a sagittal section through the front of the eyeball. (Label for 'Conjunctiva' visible at center-left.) | |
 Horizontal section of the eyeball. (Conjunctiva labeled at upper left.) | |
| Details | |
| Artery | lacrimal artery, anterior ciliary arteries |
| Nerve | supratrochlear nerve |
| Identifiers | |
| Latin | tunica conjunctiva |
| MeSH | D003228 |
| TA98 | A15.2.07.047 |
| TA2 | 6836 |
| FMA | 59011 |
| Anatomical terminology | |
The conjunctiva lines the inside of the eyelids and covers the sclera (white part of the eye). It is composed of non-keratinized, stratified columnar epithelium with goblet cells, and also stratified columnar epithelium.
Function
The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears than the lacrimal gland.[1] It also contributes to immune surveillance and helps to prevent the entrance of microbes into the eye.
Anatomy
The conjunctiva is typically divided into three parts:
| Part | Area |
|---|---|
| Palpebral or tarsal conjunctiva | Lines the eyelids. |
| Bulbar or ocular conjunctiva | Covers the eyeball, over the anterior sclera. This region of the conjunctiva is tightly bound to the underlying sclera by Tenon's capsule and moves with the eyeball movements. |
| Fornix conjunctiva | Forms the junction between the bulbar and palpebral conjunctivas. It is loose and flexible, allowing the free movement of the lids and eyeball.[2] |
Sensory innervation
Sensory innervation of the conjunctiva is divided into four parts:[3]
| Area | Nerve |
|---|---|
| Superior | |
| Inferior | Infraorbital nerve |
| Lateral | Lacrimal nerve (with contribution from zygomaticofacial nerve) |
| Circumcorneal | Long ciliary nerves |
Histology
The conjunctiva consists of non-keratinized, both stratified squamous and stratified columnar epithelium, with interspersed goblet cells.[4] The epithelial layer contains blood vessels, fibrous tissue, and lymphatic channels.[4] Accessory lacrimal glands in the conjunctiva constantly produce the aqueous portion of tears.[4] Additional cells present in the conjunctival epithelium include melanocytes, T and B cell lymphocytes.[4]
Diseases and disorders
Disorders of the conjunctiva and cornea are a common source of eye complaints.
The surface of the eye is exposed to various external influences and is especially susceptible to trauma, infections, chemical irritation, allergic reactions and dryness.
The conjunctiva can become inflamed due to an infection or an autoimmune response. This is known as conjunctivitis and commonly referred to as pinkeye.
Conjunctival irritation can occur for a wide variety of reasons including dry eye and overexposure to VOCs (Volatile organic compounds).
Leptospirosis, an infection with Leptospira, can cause conjunctival suffusion, which is characterized by chemosis, and redness without exudates.
With age, the conjunctiva can stretch and loosen from the underlying sclera, leading to the formation of conjunctival folds, a condition known as conjunctivochalasis.[5][6]
The conjunctiva can be affected by tumors which can be benign, pre-malignant or malignant.[7]
See also
Additional images
-
Sagittal section through the upper eyelid. -
Extrinsic eye muscle. Nerves of orbita. Deep dissection.
References
- ^ London Place Eye Center (2003). Conjunctivitis. Retrieved July 25, 2004.
- ^ Eye, human Encyclopaedia Britannica
- ^ http://web.archive.org/web/20130214055618/http://www.nda.ox.ac.uk:80/wfsa/html/u06/u06_b06.htm. Archived from the original on February 14, 2013. Retrieved January 18, 2013.
{{cite web}}: Missing or empty|title=(help); Unknown parameter|deadurl=ignored (|url-status=suggested) (help) - ^ a b c d Goldman, Lee. Goldman's Cecil Medicine (24th ed.). Philadelphia: Elsevier Saunders. p. 2426. ISBN 1437727883.
- ^ "Conjunctivochalasis - Medical Definition". Medilexicon.com. Retrieved 2012-11-13.
- ^ WL Hughes Conjunctivochalasis. American Journal of Ophthalmology 1942
- ^ Biswas, J.; Varde, M. (2009). "Ocular surface tumors". Oman Journal of Ophthalmology. 2: 1–2. doi:10.4103/0974-620X.48414. PMC 3018098. PMID 21234216.
{{cite journal}}: CS1 maint: unflagged free DOI (link)
External links
- Medicinenet.com (1999). Conjunctiva. Retrieved July 25, 2004.
- MedEd at Loyola medicine/pulmonar/images/anatomy/eyeli.jpg
