Eye & Orbit

Question 1

What are the major features of the eyelid?

Answer 1

Tarsal plates: give the eyelids their curved shape and serve as attachment sites for the eye-closing muscle orbicularis oculi

Levator palpebrae superioris (“lifter of the upper eyelid”) is the skeletal muscle that voluntarily opens the eye. Runs from the orbit to the tarsal plate

Question 2

What is this feature?

Answer 2

Conjunctiva: is a transparent mucous membrane that covers the inner surfaces of the eyelids as the palpebral conjunctiva and folds back over the anterior surface of the eye as the bulbar conjunctiva

Question 3

What are the features and function of the lacrimal apparatus?

Answer 3

Function: moistens eye

The lacrimal gland produces lacrimal fluid which enters the conkunctival sac through excretory ducts.

Blinking spreads the fluid across the eyeball through the lacrimal punctum which empties into a small tube the lacrimal canaliculus.

It then flows through the lacrimal sac and flows into the nasolcrimal duct which empites into the nasal cavity.

Question 4

What are the extrinsic eye muscles?

Answer 4

Question 5

How do the muscles control eye movement?

Answer 5

Lateral rectus: Moves eye laterally

Medial rectus: Moves eye medially

Superior rectus: Elevates eye and turns it medially

Inferior rectus: Depresses eye and turns it medially

Inferior oblique: Elevates eye and turns it laterally

Superior oblique:Depresses eye and turns it laterally

Question 6

Answer 6

Question 7

Answer 7

• A: Optic nerve
• B: Retina
• C: Choroid
• D: Sclera

Question 8

Answer 8

• The fibrous layer is the most external layer.
• It consists of dense connective tissue arranged into two different regions:
  
  • Sclera
  • Cornea

Question 9

Answer 9

• A: Vascular Layer
• B: Iris
  
  • Sphincter pupilae (bright light, near vision)
  • Dilator pupilae (dim light, far vision)
• C: Ciliary body
  
  • Muscular (focuses lens)
  • Connects choroid with iris
  • Ciliary process secretes aqueous humour
• D: Choroid
  
  • Vascular, darkly pigmented membrane
  • Brown colour - from melanocytes
  • Prevents scattering of light rays

Question 10

Answer 10

Question 11

Answer 11

• A: lens
• B: iris
• C: cornea
• D: pupil
• E: aqueous
• F: conjunctiva
• G: sclera

Question 12

Answer 12

• A: vitreous
• B: Retina
• C: Macula
• D: Optic nerve

Question 13

Answer 13

Question 14

Answer 14

• A: Pigmented epithelial cells
• B: Cone cells
• C: Rod cells
• D: Bipolar cells
• E: Gengillion cells

Question 15

What are the function of rods and cones of the retina?

Answer 15

• Rods
  
  • More light sensitive
  • Vision in dim light (grey and fuzzy)
• Cones
  
  • High acuity, colour vision
  • 3 types: blue, green, red

Question 16

Answer 16

• A: Macula
  
  • Macula lutea
    
    • Contains mostly cones
    • absorbs excess blue and UV
• Optic disc
  
  • nasal side of fovea
  • no retina
  • blind spot
  • ganglion cells exit retina to form optic nerve

Question 17

What is this feature and what is its function?

Answer 17

Fovea centralis

• centre of macula
• contains only cones
• max visual acuity
• in anterior-posterior axis

Question 18

Answer 18

• A: Macula lutea with fovea centralis at the very centre
• B: Central retinal a. (branch)
• C: Central retinal v. (branch)
• D: Optic disc

Question 19

What are the fluid holding chambers of the eye?

Answer 19

• Anterior chamber
  
  • between cornea and iris
• Posterior chamber
  
  • between iris and lens
  • aqeous humor
    
    • renewed continuously
    • supplies nutrients to lens and cornea
• Posterior segment
  
  • vitreous humour
    
    • transmits light
    • supports lens
    • maintains intraocular pressure
• Lens
  
  • Thick, transparent, biconvex disc
  • Held in place by its ciliary zonule

Question 20

Answer 20

• A: Retina
• B: Optic nerve
• C: Optic chiasm (crossed and uncrossed)
• D: Lateral geniculate nucleus (thalamus)
• E: Primary visual cortex

Question 21

Answer 21

• A: Ciliary muscle
• B: Suspensory ligaments
• C: Sclera
• D: Choroid
• E: Retina