Conjunctiva Flashcards
What is the Conjunctiva
Thin, translucent mucous membrane that runs from the limbus, over the anterior sclera, forms a cul-de-sac at the superior
and inferior fornices, and turns anteriorly to line the eyelids
What are the 3 functions of the Conjunctiva?
- Ensures smooth movement of eyelids
- Helps lubricate eye by producing mucus and tears
- Contributes to immune system by preventing microbes from entering eye
What type of tissue makes up the conjunctiva?
Non-keratinized, both stratified squamous and stratified columnar
epithelium
What types of cells are within the epithelial layer of the conjunctiva?
What other structures are contained in the conjunctiva?
Goblet cells, melanocytes, T cells, B cells
Blood vessels, fibrous tissue, lymphatic channels, accessory lacrimal glands
Define the 3 conjunctiva segments
- Palpebral Conjunctiva: tissue lining eyelids
- Bulbar Conjunctiva: Covers sclera
- Conjunctival Fornix: Cul-de-sac connecting palpebral and bulbar sections
Where are conjunctival stem cells found?
Most numerous in fornix region, but also found in basal layer
How many conjunctival fornices are there?
Describe their dimensions
Four... Superiorly: 8-10 mm Inferiorly: 8-10 mm Laterally: 14 mm (extends posterior to globe) Medially: 7 mm
What is the function of the fornices?
Ease movement of globe without creating undue stretching of the conjunctiva.
Fornices = folds
What part of the conjunctiva explains why a contact lens cannot get lost behind the eye?
The dimensions of the conjunctival fornices
Describe the Mucocutaneous Junction
“Where rough becomes smooth”
The nonkeratinized squamous palpebral conjunctival epithelium is continuous with keratinized squamous epithelium of epidermis of eyelid
What are the fornices loosely attached to?
The facial extensions of the levator, tarsal, and extraocular muscles
Is the bulbar conjunctiva opaque or translucent?
Transluscent - it allows the sclera to show through
Describe loose/tight the bulbar conjunctiva is adhered to its underlying tissue
Loosley adherent until about 3 mm of the cornea where it becomes tightly adherent and merges with the underlying Tenon’s capsule and sclera.
What is a sub-conunctival hemorrhage?
Mild amount of blood trapped between the bulbar conjuntiva and the underlying episclera (mild, moderate, severe).
It is just like a bruise under your skin, except you can see the blood because of the transparency of the conj
What and where is the Plicae Semilunaris?
Crescent-shaped fold of conjunctiva at the medial canthus
What is the Plicae Semilunaris composed of?
The epithelium is 8-10 cells thick and contains numerous goblet cells. The stroma is highly vascularized, containing smooth muscle fibers and adipose tissue.
What is the function of the Plicae Semilunaris?
Allow full lateral movement of the eye without tissue stretching
Give an example of a something that can irritate the Plicae Semilunaris. What would this cause?
Allergies - cause inflammation
What is the caruncle?
A mound of tissue that overlies the medial edge of the plica semilunaris
What is the caruncle composed of?
- Nonkeratinized epithelium
- Accessory lacrimal glands
- Skin elements: hair follicles, sebaceous glands, sweat glands
What is likely the source for the occasional accumulation of matter in the medial canthus of a healthy eye?
Sebaceious glands of caruncle
What is the blood supply of the palpebral conjuntiva?
Palpebral arcades of the lids; they anastomose with each other on both sides of the tarsal plate
What is the blood supply of the fornices?
Branches from the palpebral arcades extend into the fornices of the lid
What is the blood supply of the bulbar conjunctiva?
The palpebral arcades branch to create tertiary branches that extend into the bulbar conjunctiva and anastomose with the anterior conjunctival arteries of the anterior ciliary arteries
Describe the venous drainage of the conj.
Veins parallel the arteries but are more numerous. They drain into the palpebral and ophthalmic veins
Are there more veins or arteries draining/supplying the conj?
Veins
Where do conjunctival lymphatics from the lateral aspect of the eyelid drain to?
Parotid lymph node
Where do conjunctival lymphatics from the medial aspect of the eyelid drain to?
Submandibular lymph node
What innervates the bulbar conjunctiva?
Sensory innervation carried through the long ciliary nerves
What innervates the superior palpebral conjunctiva?
Sensory innervation is provided by the frontal and lacrimal branches of the ophthalmic nerve (V1)
What innervates the inferior palpebral conjunctiva?
Provided by lacrimal nerve and the infraorbital branch of the maxillary nerve
What is conjunctivitis?
Any inflammation of the conjunctiva
What causes conjunctivitis?
A variety of factors, but the most common are bacterial or viral invasion and allergic reaction
What is Epidemic Kerato-Conjunctivitis (EKC)?
Very severe bacterial pink eye
What is Tenon’s Capsule?
- Thin fibrous sheet below the conjunctival stroma
- Fascial cavity within which the globe can move
- Protects and supports the globe
- Attaches globe to the orbital connective tissue
