Palpebral Aperture

Question 1

Define the term insertion

Answer 1

The point of attachment of a tendon or ligament onto the skeleton or other part of the body

Question 2

What is the palpebral aperture?

Answer 2

the opening between the upper and lower eyelids when the eye is open. ie the exposed part of the eye when the eyelids are separated

Question 3

4 functions of eyelids

Answer 3

• shield from monor injuries
• remove foreign objects (blinking)
• control light entry (can improve distance vision)
• contributes and maintains tear film

Question 4

Functions of tarsal portions and tarsal plates

Answer 4

• provide structural support and shape to eyelids
• muscle attachment ( muller’s muscles)
• attachment of eyelashes
• conjunctiva attachment
• facilitate the function and movement of eyelids

Question 5

What are tarsal plates

Answer 5

Dense, fibrous structures primarily composed of collagen fibres, found within the upper and lower eyelids of mammals. Serve as supportive frameworks for eyes.

Question 6

Upper and lower tarsal portion measurements

Answer 6

Upper 29mm x 10mm
Lower 29mm x 5mm

Question 7

Describe the postions of the lower and upper eyelids in relation to the cornea

Answer 7

Edge of lower eyelid close to edge of cornea
Edge of upper eyelid overlaps cornea

Question 8

What is the orbital septum and septum portion of eyelids

Answer 8

Septal portion refers to the area of the eyelids that extends from outside tarsal portions to rim of orbit
The orbital septum is a thin fibrous membrane that extends from the margin of eyelids to the periosteum (connective tissue) of orbit

Question 9

What are palpebral furrows

Answer 9

External skin folds formed where tarsal and septal join
Also known as lid creases

Question 10

What is the canthus and the two types

Answer 10

Canthus is the corner where the upper and lower eyelids meet
1. Medial canthus- nasal
2. Lateral canthus- temporal

Question 11

What are epicanthal folds

Answer 11

Skin fold of the upper eyelid that covers the inner corner if the eye
Commonly observed in individuals of east asian descent however is present in foetus of all races

Question 12

What are tarsal plates made of

Answer 12

Tough collagenous connective tissue

Question 13

What is the function of tarsal (Meibomian) glands

Answer 13

Produce meibum, an oily substance that lubricates eyelids, prevents tear evaporation,

Question 14

What condition is a result of dysfunction of tarsal glands

Answer 14

Meibomian gland dysfunction
Evaporative dry eye

Question 15

Describe how muscles work to widen the palpebral fissure

Answer 15

Upper eyelid is pulled up by levator and Muller’s muscles
Lower eyelid is pulled down by a single inferior tarsal muscle

Question 16

What conditions are a result of dysfunction of lid muscles esp levator

Answer 16

Ptosis (dropping of upper eyelid)
Lid droop

Question 17

Describe how the palpebral aperture closes

Answer 17

Orbicularis oculi muscles have circular and radial fibres.
When orbicularis oculi muscles contract, circular fibers tighten, pulling eyelids together from the sides, while radial fibers pull the eyelids downwards

Question 18

What is the function of canthal tendons

Answer 18

Connect eyelids to the eye orbit

Question 19

Describe the differences in lid closure for muscles in pretarsal and orbital portions

Answer 19

Pretarsal- reflex/spontaneous lid closure eg foreign object sensation
Orbital- voluntary eyelid closure eg squinting

Question 20

What is entropion?

Answer 20

Eye condition where eyelid (usually lower), turns inwards causing eyelashes and skin of eyelid to rub against surface if eye leafing to irritation and redness

Caused by chronic overreaction of pre-septal orbicularis

Question 21

What is the plica semilunaris

Answer 21

Small, crescent shaped fold of conjunctiva located at inner corner of eye, adjacent to medial canthus

Question 22

What is the lacrimal caruncle?

Answer 22

Small fleshy triangular structure located at the inner of the ye adjacent of medial canthus containing glands and fine hairs