EYELIDS

Question 1

EYELIDS DERIVED FROM?

Answer 1

SURFACE ECTODERM

Question 2

WHAT INITIATES SEPARATION OF LIDS?

Answer 2

keratinisation of surface epithelial cells

Question 3

EYELID FUNCTIONS

Answer 3

• protection
• contributes to tear production
• spreads tears across cornea
• aids in tear drainage

Question 4

OPENING BETWEEN LIDS FORMS WHAT?

Answer 4

PALPEBRAL FISSURE

Question 5

STRUCTURE OF EYELID

Answer 5

• skin
• musculature
• fibrous layer (incl. tarsal glands)
• palpebral conjunctiva

Question 6

MUSCULATURE OF EYELIDS

Answer 6

• orbicularis oculi
• levator palpebrae superioris
• tarsal muscles

Question 7

ORBICULARIS OCULI

Answer 7

• striated voluntary
• holds lid against eye
• assists spreading tears
• contraction causes lids to close
• CN VII
• orbital part (forced lid closure)
• palpebral part (reflex blinking)

Question 8

LEVATOR PALPEBRAE SUPERIORIS

Answer 8

• striated voluntary
• found in upper lid
• becomes a tendon as it enters the lid
• involved in raising upper lid
• CN III

Question 9

TARSAL MUSCLE

Answer 9

• smooth
• sympathetic innervation
• lines levator + aids it’s action
• wide-eyed expression of fear

Question 10

FIBROUS LAYER OF LIDS

Answer 10

• gives lids shape + firmness

- contains tarsal glands (modified sebaceous glands)

Question 11

PALPEBRAL CONJUNCTIVA OF LIDS

Answer 11

• lines inner surface of lids
• mucous membrane
• non-keratinised epithelium
• forms conjunctival sac
• goblet cells produce mucin
• vascular TC provides oxygen to cornea when eye is closed