ANATOMY OF CONJUNCTIVA.pptx anatomymymymymymymymym

anatomy of conjunctiva

1. ANATOMY OF CONJUNCTIVA -ABHILASH S NANDA PHASE 3 PART 1 NMCRI, CHIKKABALLAPURA

2. CONJUNCTIVA It is a translucent mucous membrane which lines the posterior surface of the eyelids and anterior surface of the eyeball. It stretches from the lid margin to the limbus and encloses a complex space called CONJUNCTIVAL SAC which is open at the palpebral fissure.

3. PARTS OF CONJUNCTIVA PALPEBRAL CONJUNCTIVA Marginal Conjunctiva Tarsal Conjunctiva Orbital Part BULBAR CONJUNCTIVA CONJUNCTIVAL FORNIX

4. PALPEBRAL CONJUNCTIVA It lines the lid and can be subdivided into 3 parts: Marginal Conjunctiva : From Lid Margin to 2 mm back. It is a transition zone between the skin and Conjunctiva Proper. Tarsal Conjunctiva : Thin, Transparent and highly Vascular. Firmly Adherent to the tarsal plate. Tarsal glands are seen through as yellow streaks. Orbital Part : Lies loosely between the tarsal plate and fornix.

5. BULBAR CONJUNCTIVA & CONJUNCTIVAL FORNIX It is thin, transparent and lies loose over the underlying structures and thus can be moved easily. The Episcleral tissue and the Tenon’s capsule separates it from the underlying Sclera. Limbal Conjunctiva is the 3mm ridge of Bulbar Conjunctiva around the Cornea. At the limbus, the conjunctival Epithelium becomes continuous with that of cornea. 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 Sclerocorneal junction. CONJUNCTIVAL FORNIX joins the bulbar conjunctiva with the palpebral conjunctiva. It is a continuous sac which is broken on the medial side by caruncle and plica semilunaris which is subdivided into superior, inferior, medial and lateral fornices .

6. STRUCTURE OF CONJUNCTIVA Histologically, the conjunctiva consists of 3 layers namely, Epithelium: 2-5 layered, non-keratinized epithelium which also contains GOBLET CELLS. The layer of epithelial cells in conjunctiva varies from region to region and in its different parts as follows: Marginal Conjunctiva : 5 layered stratified squamous epithelium. Tarsal Conjunctiva : 2 layered epithelium with superficial cylindrical cells and deep layer of flat cells. Fornix and Bulbar Conjunctiva : 3 layered epithelium: a superficial layer of cylindrical cells, middle layer of polyhedral cells and a deep layer of cuboidal cells. Limbal Conjunctiva : Stratified Squamous epithelium

7. Adenoid Layer [LYMPHOID LAYER]: It consists of fine connective tissue reticulum in the meshes of which lie Lymphocytes. It is not present since birth but develops after 3-4 months of life. For this reason, conjunctival inflammation in an infant does not produce follicular reaction. Fibrous layer: It consists of a meshwork of collagenous and elastic fibres and is thicker than the adenoid layer. This layer contains vessels and nerves of the conjunctiva. It blends with the underlying Tenon’s capsule in the region of the Bulbar Conjunctiva.

8. GLANDS OF CONJUNCTIVA MUCIN SECRETING CELLS: Goblet cells: Unicellular glands Crypts of Henle: present in tarsal conjunctiva Glands of Manz : present in limbal conjunctiva. They secrete mucus which is essential for wetting the cornea and conjunctiva. ACCESSORY LACRIMAL GLANDS : Glands of Krause: present in the subconjunctival connective tissue of fornices . Glands of Wolfring : present in the upper border of Upper Tarsus and lower border of Lower Tarsus.

9. Plica Semilunaris : It is a pinkish crescentic fold of conjunctiva, present in the medial canthus. It is a vestigial structure in human beings and represents the Nictating Membrane (or third eyelid) in lower animals. Caruncle: It is a small, ovoid, pinkish mass, situated in the inner canthus, just medial to the plica semilunaris. It is a piece of Modified Skin and so is covered with stratified squamous epithelium and contains sweat glands, sebaceous glands and hair follicles

10. BLOOD SUPPLY OF CONJUNCTIVA ARTERIES : Palpebral Conjunctiva and fornices by Peripheral and Marginal arterial arcades of eyelids. Bulbar Conjunctiva by Posterior & Anterior(branch of Anterior Ciliary Arteries) Conjunctival Arteries. The end arteries anastomose with each other to form the Pericorneal plexus. VEINS: Veins from the conjunctiva drain into the venous plexus of eyelids and some around the cornea into the Anterior ciliary veins . LYMPHATICS : Lymphatics from the lateral side drain into the Preauricular lymph nodes and those from the medial side drain into the Submandibular lymph nodes.

11. NERVE SUPPLY OF CONJUNCTIVA A Circumcorneal zone of conjunctiva is supplied by the branches from long ciliary nerves which supply the cornea. Rest of the Conjunctiva is supplied by the branches from Lacrimal, Infratrochlear , Supratrochlear, Supraorbital and Frontal nerves .