ANATOMY of Conjunctiva

The conjunctiva is a translucent mucous membrane
which lines the posterior surface of the eyelids and
anterior aspect of eyeball. The name conjunctiva
(conjoin: to join) has been given to this mucous
membrane owing to the fact that it joins the eyeball
to the lids. It stretches from the lid margin to the
limbus, and encloses a complex space called
conjunctival sac which is open in front at the
palpebral fissure.

Parts of conjunctiva
Conjunctiva can be divided into three parts (Fig. 1):
1. Palpebral conjunctiva. It lines the lids and can be
subdivided into marginal, tarsal and orbital
conjunctiva.
i. Marginal conjunctiva extends from the
  lid margin
to about 2 mm on the back of lid up to a shallow
groove, the sulcus subtarsalis. It is actually a
transitional zone between skin and the conjunctiva
proper.

ii. Tarsal conjunctiva is thin, transparent and highly
vascular. It is firmly adherent to the whole tarsal
plate in the upper lid. In the lower lid, it is
adherent only to half width of the tarsus. The
tarsal glands are seen through it as yellow streaks.
iii.Orbital part of palpebral conjunctiva lies loose
between the tarsal plate and fornix.

2. Bulbar conjunctiva. It is thin, transparent and lies
loose over the underlying structures and thus can be
moved easily. It is separated from the anterior sclera
by episcleral tissue and Tenon's capsule. A 3-mm ridge
of bulbar conjunctiva around the cornea is called
limbal conjunctiva. In the area of limbus, the
conjunctiva, Tenon's capsule and the episcleral tissue
are fused into a dense tissue which is strongly
adherent to the underlying corneoscleral junction.
At the limbus, the epithelium of conjunctiva becomes
continuous with that of cornea.
 

3. Conjunctival fornix. It is a continuous circular
cul-de-sac which is broken only on the medial side
by caruncle and the plica semilunaris. Conjunctival
fornix joins the bulbar conjunctiva with the palpebral
conjunctiva. It can be subdivided into superior,
inferior, medial and lateral fornices.

Fig. 1. Parts of conjunctiva and conjunctival glands.