Topic 12 Ocular Appendages Flashcards
what is the conjunctiva?
thin and almost transparent mucous membrane that lines the inside of the eyelids and on the anterior surface of the eyeball.
what are the 3 regions of the conjunctiva?
- Palpebral/Tarsal conjunctiva (lining the lids-upper palpebral & lower palpebral)
- Bulbar conjunctiva (lining the exposed part of the globe/sclera)
- Forniceal conjunctiva (junction of the palpebral & bulbar conjunctiva- upper & lower fornix)
what are the 2 layers of the conjuctiva?
Epithelium
•Consists of non-keratinised epithelium & goblet cells.
•Goblet cells provide mucin (inner layer of the tear film which lines the corneal epithelium).
Stroma
•Contains the accessory glands of Krause and Wolfring. (contribute the middle layer of the tear film-the aqueous layer)
what is the 2 blood supply of the conjunctiva?
Anterior ciliary arteries and lacrimal artery
what is the nerve supply of the conjunctiva?
Trigeminal nerve (CN5)
what are eyelashes/cilia and what is their function
- located in both eyelids, usually grow outward
- part of the defence mechanism of the eye, initiate reflex blink on the slightest contact with foreign particles
what are the 5 layers of the eyelid?
- skin
- sub-cutaneous tissue
- muscles
- sub-muscular areilar tissue
- tarsal plate
what does the skin of the eyelid contain? (Glands included)
-outermost layer of the eyelids
contains the
- cilia (eyelashes), defence mechanism-reflex blink
- sweat glands, Glands of Moll
- sebaceous glands (Glands of Zeis) contributes to the lipid layer of the tear film
what does the sub-cutaneous tissue of the eyelid contain?
Connective tissue below the skin
what does the muscle layer of the eyelid contain? (4 muscles) what are their functions?
- Levator Palpebrae Superioris (LPS) muscle aids in elevation of the upper eyelid (lid opening)
- Tarsal/Muller’s muscle keeps the upper eyelid open (sustains eyelid opening)
- Orbicularis Oculi muscle helps with eyelid closure
- Riolan’s muscle insures good closure of the lid
what does the sub-muscular areolar tissue layer of the eyelid contain?
connective tissue below the muscle layer
what does the tarsal plate layer of the eyelid contain?
- posterior most layer of the eyelids
- fibrous tissue plate that gives shape & firmness to the lids
- contains the meibomian/tarsal glands which contribute to the lipid layer of the tear film
what are the 3 main functions of the eyelid?
- reflex blink initiated by the eyelashes
- lid movements (opening & closure)
- blinking aids in spreading of tears and keeps the ocular surface moist. Also removes dust
what is the 2 blood supply and 4 nerve supply to the eyelid?
Facial artery
Lacrimal artery
Trigeminal nerve (CN5) upper eyelid, lower eyelid
Facial nerve (CN7) Orbicularis oculi muscle, Riolan muscle, lower eyelid
Oculomotor nerve (CN3) LPS muscle
Sympathetic branch Muller’s muscle
what is the function of the eyebrows? What are the muscles associated with eyebrow movement?
Functions: prevents sweat from dripping into the eyelids
plays a role in facial expression
Orbicularis oculi (depression) occipito frontalis (elevation)