Anatomy of Conjunctiva - bulbar, palpebral,tarsal, fornix conjunctiva,glands & blood supply

Conjunctiva:

Conjunctiva is a translucent mucous membrane covering the anterior part of the eyeball and the inner surface of eyelids. It extends from the lid margins to the limbus connecting the eyeball and lids, hence hence the name conjunctiva (conjoin-to join). 

Parts of Conjunctiva:

It has three parts, they are

1. Palpebral conjunctiva:

It lies on the lids and can be subdivided into marginal, tarsal and orbital parts.

2.Conjunctival fornix:

It connects the palpebral and bulbar conjunctiva. It is a circular cul-de-sac which is interrupted medially by the plica semilunar is and caruncle.

3.Bulbar conjunctiva:

It covers the anterior sclera and it is freely movable except in limbal conjunctiva. Limbal conjunctiva is area around the cornea where the Conjunctiva, episcleral tissue and the Tenon's capsule are fused to form a dense tissue.

Histology of conjunctiva:

Histologically,it can be divided into 3 layers

1.Epithelial layer,is a non-keratinized epithelium and the layer varies from 2-5 in different regions of the Conjunctiva.

2.Adenoid layer, contains lymphocytes. It develops after 3 months of birth.

3.Fibrous layer,is a meshwork of collagen and elastic fibres. This layer contains the blood vessels and nerves.

Plica semilunaris:

It is a crescent shaped fold of conjunctiva present in the medial canthus. It is a vestigeal structure in human beings and represent the third eye in lower vertebrates.

 Caruncle:

Caruncle is a small ovoid mass present just medial to the plica semilunaris. It contains hair follicles, sebaceous and sweat glands.

Glands of Conjunctiva:

Mucin secreating glands:

     -Glands of Manz

     -Crypts of Henle

     -Globlet cells

Lacrimal glands:

      -Glands of Krause

      -Glands of Wolfring.

Blood supply of conjunctiva

Arteries:

-Anterior conjunctival artery (branch of a ciliary artery)

-Posterior conjunctival artery (branch of lacrimal artery)

-Palpebral branch of nasal arteries.

Veins:

Veins drains into venous plexus of eyelids.

Lymphatics:

-From lateral half drain into preauricular nodes

-From medial half drain into submandibular nodes.

Nerve supply of conjunctiva

-Ophthalmic division of Trigeminal Nerve.

Bacterial flora in Conjunctiva:

Conjunctiva also contains some amount of bacterial flora. It harbours S. aureus,S. epidermidis, Streptococcus,E.  coli,Propionibacterium acnes and Coryne-

bacterium xerosis.