ANATOMY - Eye

Question 1

Which two species have an eyeball with an anterior-posterior compression?

Answer 1

Cattle
Horses

Question 2

What are the two main segments of the eyeball?

Answer 2

Anterior segment
Posterior segment

Question 3

Which structure separates the anterior and posterior segments of the eyeball?

Answer 3

Lens

Question 4

What are the two chambers within the anterior segment of the eyeball?

Answer 4

Anterior chamber
Posterior chamber

Question 5

What are the boundaries of the anterior chamber in the anterior segment?

Answer 5

The anterior chamber is between the cornea and the iris

Question 6

What are the boundaries of the posterior chamber of the anterior segment?

Answer 6

The posterior chamber is between the iris and the lens

Question 7

What is aqueous humor?

Answer 7

Ultra-filtrate of plasma located in the anterior segment of the eyeball

Question 8

What is vitreous humor?

Answer 8

Gel-like substance located in the posterior segment of the eyeball

Question 9

What are the three concentric tunics of the eye?

Answer 9

Fibrous tunic
Vascular tunic
Neural tunic (retina)

Question 10

What are the two functions of the fibrous tunic?

Answer 10

Resists internal pressure
Maintains eyeball shape

Question 11

What are the two components of the fibrous tunic?

Answer 11

Cornea
Sclera

Question 12

What is the point of attachment between the cornea and sclera?

Answer 12

Limbus

Question 13

What allows the cornea to remain transparent?

Answer 13

Organised arrangement of connective tissue fibres and the continual removal of lacrimal fluid

Question 14

What are the three layers of the cornea?

Answer 14

Epithelium
Substantia propria (connective tissue)
Descemet’s membrane

Question 15

What is the importance of Descemet’s membrane when using fluorescein to asses corneal ulcers?

Answer 15

Descemet’s membrane does not take up fluorescein so it acts as a protective barrier between the fluorescein and the deeper structures of the eye. This allows the dye to specifically highlight any ulcers in the substantia propria without affecting underlying layers

Question 16

What are the two main components of the sclera?

Answer 16

Collagen fibres
Elastic fibres

Question 17

What is the vagina bulba?

Answer 17

Thin membranous covering which separates the sclera from the retrobulbar fat to allow for smooth movement of the eyeball within the orbit

Question 18

What are the three components of the vascular tunic?

Answer 18

Iris
Choroid
Ciliary body

Question 19

What is the iris?

Answer 19

The iris is a smooth muscle sphincter that controls the size of the pupil and thus regulates the amount of light that enters the eye

Question 20

What is the term used for constriction of the pupil?

Answer 20

Miosis

Question 21

What is the term used for dilation of the pupil?

Answer 21

Mydriasis

Question 22

What are iridic granules?

Answer 22

Pigmented, roughened prominences present on the pupillary margin of the eye in horses and ruminants

Question 23

What are the four functions of the ciliary bodies?

Answer 23

Anchors lens
Alter shape of lens through contraction
Produces aqueous humor
Drains aqueous humor

Question 24

Which disease occurs if aqueous humor fails to drain from the anterior segment of the eyeball?

Answer 24

Glaucoma

Question 25

What is the choroid?

Answer 25

Vascular tissue running from the optic nerve to the limbus

Question 26

What is the function of the choroid?

Answer 26

The choroid supplies nutrients to the neural tunic (retina)

Question 27

Which arteries are found within the choroid?

Answer 27

Ciliary arteries

Question 28

Which veins are found within the choroid?

Answer 28

Vorticose veins

Question 29

What is the tapetum lucidum?

Answer 29

Reflective membrane which reflects light back through the retina, increasing the chances of photons stimulating the photoreceptors in the retina to enhance visual sensitivity under low-light conditions

Question 30

Which species does not have a tapetum lucidum?

Answer 30

Pigs

Question 31

What are the two divisions of the neural tunic (retina)?

Answer 31

Pars optica retinae Pars ceca retinae

Question 32

What is the difference between the pars optica retinae and the pars ceca retinae?

Answer 32

Pars optica retinae is the portion of the neural tunic (retina) which has photoreceptors cells and is involved in light detection however the pars ceca retinae has no photoreceptor cells

Question 33

What is the optic disc?

Answer 33

The point of entry of cranial nerve II (optic nerve) into the neural tunic (retina)

Question 34

What are the four adnexal structures of the eye?

Answer 34

Orbit Extraocular muscles Palpabrae (eyelids) Lacrimal apparatus

Question 35

Which three bones of the skull make up the orbit?

Answer 35

Frontal bone Lacrimal bone Zygomatic bone

Question 36

What are the four rectus extraocular muscles?

Answer 36

Dorsal rectus muscle Ventral rectus muscle Medial rectus muscle Lateral rectus muscle

Question 37

What are the two oblique extraocular muscles?

Answer 37

Dorsal oblique muscle Ventral oblique muscle

Question 38

What is the function of the dorsal oblique muscle?

Answer 38

Rotation of the eye downwards and outwards

Question 39

What is the function of the ventral oblique muscle?

Answer 39

Rotation of the eye upwards and inwards

Question 40

Which extraocular muscle can retract the eyeball into the orbit?

Answer 40

Retractor bulbi muscle

Question 41

What are the two true eyelids?

Answer 41

Upper palpabrae Lower palpabrae

Question 42

Where do the upper and lower palpabrae meet?

Answer 42

Commissures

Question 43

What is the name of the space between the upper and lower palpabrae?

Answer 43

Palpabral fissure

Question 44

What are the three layers of the palpabrae (eyelids)?

Answer 44

Skin Musculofibrous layer Conjunctiva

Question 45

What are the two skeletal muscles in the musculofibrous layer of the palpabrae (eyelids)?

Answer 45

Obicularis oculi muscle Levator palpabrae superiosus muscle

Question 46

What is the fibrous plate within the musculofibrous layer of the palpabrae (eyelids)

Answer 46

Tarsal plate

Question 47

What is the function of the tarsal glands surrounding the tarsal plate?

Answer 47

Production of the lipid layer of the lacrimal fluid (tears)

Question 48

What is the name of the space between the palpabrae (eyelids) and the eyeball?

Answer 48

Conjunctival sac

Question 49

What is the name of the lacrimal gland associated with the third eyelid?

Answer 49

Gland of the third eyelid

Question 50

What is 'cherry eye'?

Answer 50

Prolapse of the gland of the third eyelid

Question 51

What is the function of the lacrimal apparatus?

Answer 51

Production of lacrimal fluid (tears)

Question 52

What are the two functions of lacrimal fluid (tears)?

Answer 52

Protection of the cornea Nutrient provision to the cornea

Question 53

What are the three main glands which make up the lacrimal apparatus?

Answer 53

Lacrimal gland Gland of the third eyelid Tarsal glands

Question 54

Describe the drainage root for lacrimal fluid (tears)?

Answer 54

Lacrimal fluid is drained into slits adjacent to the lacrimal caruncle (tear duct) known as puncta lacrimalia which drain into the lacrimal sac followed by the nasolacrimal duct and into the nasal vestibule

Question 55

What are the three layers of the lacrimal fluid (tears)?

Answer 55

Lipid layer Mucin layer Aqueous layer

Question 56

What produces the mucin layer of lacrimal fluid (tears)?

Answer 56

Conjunctival goblet cells

Question 57

What is the main artery supplying the eye?

Answer 57

External ophthalmic artery

Question 58

Which six cranial nerves innervate the eye?

Answer 58

Cranial nerves II to VII