The conjunctiva is a mucous membrane that lines the inner surface of the eyelids and covers the anterior sclera of the eye. It has two main parts - the palpebral conjunctiva lines the inner surface of the eyelids, and the bulbar conjunctiva covers the white sclera of the eyeball. The conjunctiva helps lubricate the eye and contributes to immune function. Histologically, it consists of an epithelial layer, adenoid layer containing lymphocytes, and a fibrous layer. Goblet cells within the epithelium secrete mucus. The conjunctiva receives its blood supply from the eyelid arteries and drains into the ophthalmic veins.