Function of the Eyelids

Question 1

Main goal of the eyelids

Answer 1

To protect the globe!

Question 2

Stimulation of sensory nerves leads to contraction of which muscle?

Answer 2

Orbicularis oculi. This results in the contraction of the muscle, which extends/lengthens the eyelid and closes the eye. Upon closure, the globe recess 1.5 mm into the orbit.

Question 3

3 different ways to close your eyes

Answer 3

Forced
Reflexive
-Tactile
-Optical 
-Auditory  
Spontaneous

Question 4

3 reflexive ways to close your eyes

Answer 4

Tactile- Touching the cornea, conjunctiva, eyelash, eyelid skin and eyebrow.
Optical- Viewing bright lights (dazzle) or unexpected/threatening objects (menace)
Auditory- Hearing unexpected/threatening sound (menace)

Question 5

Tactile reflex pathway

Answer 5

Stimulation to the eye– Trigeminal V (sensory) – brain — Facial VIII (motor) and orbicularis oculi

Question 6

Optical reflex pathway

Answer 6

Dazzle or menage – ON II – brain – CN VII (facial) – orbicularis occuli

Question 7

Auditory reflex pathway

Answer 7

Sound – CN VIII (vestibular cholerar nerve/ hearing and balance) – brain – CN VII – orbicularis occuli – eyes close globe recedes

Question 8

Spontaneous blinking occurs every

Answer 8

3-8 seconds
This is important to prevent dry eye. Blinking initiates a cycle of tear secretion, dispersal, and drainage. Removes debris from the ocular surface

Question 9

Which glands/cells contribute to the tear film?

Answer 9

Meibomian glands

• produce lipid portion of tear film (meibum)
• located in the tarsal plate

Goblet Cells

• Epithelial cells located in the conj
• Produce the mucin portion of the tear film

Lacrimal gland

• Located temporally in the UL
• Produces the aqueous portion of the tear film

Lacrimal accessory glands of Krause and Wolfring

• Located in the Conjunctiva
• Produce aqueous portion of the tear film

Question 10

How is the tear film secreted and dispersed?

Answer 10

Eyelid closure leads to secretion by the tear film components- Aqueous, mucin, meibum

Eyelid opening leads to dispersal across the ocular surface (conj and sclera)

Question 11

Where do tears exit from the eye?

Answer 11

The UL and LL meet at the temporal canthus and zip towards the medial canthus. This pushes tears into the punch by capillary action, which is the movement of water without external forces. Additionally, the action of Horner’s muscle (part of the orbicularis oculi muscle) helps keep the eyelids tight against the globe and drain the tears into the nasolacrimal drainage system.

Question 12

Stye

Answer 12

Infected meibomian gland