Lecture 52 - Ocular Structure 1

Question 1

in dogs, what bones comprise the orbit?

Answer 1

Frontal
Lacrimal
Maxillary
Sphenoid
Zygomatic
Palatine

Question 2

what bone is present in the equine orbit but not the dogs’

Answer 2

temporal instead of maxillary

Question 3

what is retrobulbar disease

Answer 3

tumor/abscess development behind the globe which pushes the globe forward

Question 4

what is the job of the retractor bulbi mm.

Answer 4

pulls the eye back (caudally)

Question 5

what is the job of the dorsal rectus mm.

Answer 5

rotates globe upward

Question 6

what is the job of the ventral rectus mm.

Answer 6

rotates globe downward

Question 7

what is the job of the medial rectus mm.

Answer 7

rotates globe medially

Question 8

what is the job of the lateral rectus mm.? what innervates it?

Answer 8

rotates globe laterally
abducens

Question 9

what is the job of the dorsal oblique mm.? What innervates it?

Answer 9

rotates dorsal globe medially and ventrally
trochlear

Question 10

what is the job of the ventral oblique mm.

Answer 10

rotates ventral globe medially and dorsally

Question 11

what innervates the retractor bulbi mm.

Answer 11

abducens

Question 12

what is strabismus

Answer 12

deviation of the eye due to damage to oculomotor mm.

Question 13

explain the bulbar conjunctiva

Answer 13

sits over the globe itself

Question 14

explain the palpebral conjunctiva

Answer 14

sits on the eyelid

Question 15

explain the conjunctival fornix

Answer 15

creates a pocket to keep things out of the body cavity between the bulbar and palpebral

Question 16

what are the 3 layers of the tear film

Answer 16

1. lipid layer
2. aqueous layer
3. mucoid layer

Question 17

describe the drainage system of the lacrimal system

Answer 17

1. lacrimal puncta
2. canaliculi
3. nasolacrimal duct
4. nasal punctum

Question 18

what is a Jones Test?

Answer 18

used to test the lacrimal drainage system

Question 19

what are the 3 layers of the globe

Answer 19

1. fibrous tunic
2. vascular tunic
3. neural layer

Question 20

what is within the fibrous tunic

Answer 20

cornea and sclera

Question 21

what is the main difference between conjunctiva and sclera

Answer 21

the conjunctiva is a thin translucent membrane whereas the sclera is the thick, white CT

Question 22

what is within the vascular tunic

Answer 22

iris, ciliary body, and choroid

Question 23

the components of the vascular tunic are often referred to as

Answer 23

uvea

Question 24

what is within the neural layer

Answer 24

retina and optic nerve

Question 25

what is the anterior chamber

Answer 25

contains aqueous humor, between the cornea and lens

Question 26

what is the posterior chamber

Answer 26

contains aqueous humor, sits between the ciliary and lens

Question 27

what is the vitreous chamber

Answer 27

contains vitreous humor (gel) sits behind the lens

Question 28

what is contained in the anterior segment of the globe

Answer 28

• cornea
• iris
• ciliary body
• lens
• anterior & posterior chamber

Question 29

what is contained in the posterior segment of the globe

Answer 29

• choroid
• retina
• optic nerve
• vitreous chamber

Question 30

what does this structure look like on histology:

orbicularis oculi m.

Answer 30

elongated/tubular cells
peripherally located nuclei

Question 31

what facial nerves are in charge of the palpebral reflex

Answer 31

CN V (sensation) and CN VII (motor)

Question 32

what is the tarsal plate

Answer 32

sheet of dense connective tissue that maintains structural integrity and shape of eyelids

Question 33

Describe meibomian glands

Answer 33

sebaceous glands within the tarsal plate
produces meibum (lipid) component of tear film

Question 34

what does this structure look like on histology:

conjunctiva

Answer 34

stratified columnar epithelium with goblet cells

Question 35

describe the third eyelid

Answer 35

• protects and lubricates the eye
• produces aqueous component of tears
• secondary lymphoid organ

Question 36

what are the 4 layers to the cornea

Answer 36

1. epithelium
2. stroma
3. descemet’s membrane
4. endothelium

Question 37

what is the importance of the corneal endothelium

Answer 37

pumps aqueous humor out of the corneal stroma

Question 38

what cranial nerves are involved in the corneal reflex

Answer 38

CN V (sensation)
CN VI (motor to retractor bulbi)
CN VII (motor to eyelids)

Question 39

describe the dilator muscles of the iris

Answer 39

smooth mm.
sympathetic innervation

Question 40

describe the constrictor muscles of the iris

Answer 40

smooth mm.
parasympathetic innervation

Question 41

what are zonular fibers

Answer 41

connective tissue protein that secures the lens in the optical axis

Question 42

where is the origin of zonular fibers and aqueous humor

Answer 42

ciliary body

Question 43

what are the non-pigmented ciliary body epithelium responsible for

Answer 43

production of aqueous humor

Question 44

what is the iridocorneal angle and what is the clinical significance

Answer 44

space between the iris and ciliary body anteriorly

responsible for the outflow of aqueous humor (glaucoma)

Question 45

describe the anterior lens epithelial cells

Answer 45

progenitors for new lens fibers and regulates lens homeostasis

Question 46

T/F: no lens epithelial poles are found in the posterior pole

Answer 46

TRUE

Question 47

Describe the fundus

Answer 47

inside, black surface if the eye containing the retina, choroid, tapetum lucidum, and blood vessels

Question 48

____ receives and organizes visual stimuli and ____ transmits sensory to neural info

Answer 48

retina; optic nerve