5.1 Anatomy of the Orbit, Orbital Region and Eyeball

Question 1

Which 6 bones make up the orbit?

Answer 1

Frontal
Sphenoid
Ethmoid
Lacrimal
Maxilla
Zygomatic

Question 2

Name the 4 openings in the orbital cavity

Answer 2

Optic canal
Superior orbital fissure
Inferior orbital fissure
Nasolacrimal canal

Question 3

What structures lie in the optic canal?

Answer 3

Optic nerve and optic artery

Question 4

What structures lie in the superior orbital fissure?

Answer 4

Lacrimal nerve
Frontal nerve
Trochlear nerve
Oculomotor nerve
Nasociliary nerve
Abducens nerve

Superior ophthalmic vein

Question 5

What structures lie in the inferior orbital fissure?

Answer 5

Maxillary nerve
Inferior ophthalmic vein
Sympathetic nerves

Question 6

What is the purpose of the nasolacrimal canal?

Answer 6

Drains tears to nasal cavity

Question 7

Which bone are the optic canal, superior and inferior orbital fissure located in?

Answer 7

Sphenoid bone

Question 8

What is an orbital rim fracture?

Answer 8

Fracture of the bones forming the outer rim of the bony orbit ie. Maxilla, zygomatic and frontal bones

Question 9

What is a blowout fracture?

Answer 9

Contents of the orbit partially herniate into the maxillary sinus. Patient cannot look up as inferior rectus muscle is trapped

Question 10

What is exophthalmos?

Answer 10

Protrusion of the eye due to increased intraocular pressure

Question 11

What makes up the outer fibrous layer of the eyeball?

Answer 11

Sclera and cornea

Question 12

What makes up the middle vascular layer of the eyeball?

Answer 12

Choroid, iris and ciliary body

Question 13

What makes up the inner layer of the eyeball?

Answer 13

Retina

Question 14

What is retinal detachment?

Answer 14

The retina becomes free of the choroid so loses its blood supply and undergoes necrosis

Question 15

Where is fluid produced in the eye?

Answer 15

Ciliary bodies

Question 16

Where does fluid in the eye drain to?

Answer 16

Trabecular meshwork

Question 17

What is open angle glaucoma?

Answer 17

Trabecular meshwork of eye becomes blocked so there is an accumulation of fluid in the aqueous humour. Increased pressure in the eye results in damage to the optic nerve and a loss of vision

Question 18

What are cataracts?

Answer 18

Lens of the eye becomes harder and flattened

Question 19

Name the 6 muscles around the eyeball and in what direction they move it

Answer 19

Superior rectus- look superiorly
Medial rectus- look medially
Inferior rectus- look inferiorly
Lateral rectus- look laterally
Superior oblique- rotate down
Inferior oblique- rotate up

Question 20

What nerve supplies the lateral rectus muscle?

Answer 20

Abducens nerve

Question 21

What nerve supplies the superior, medial and inferior rectus muscles?

Answer 21

Oculomotor nerve

Question 22

What nerve supplies the inferior oblique muscle?

Answer 22

Oculomotor nerve

Question 23

What nerve supplies the superior oblique muscle?

Answer 23

Trochlear nerve

Question 24

How can the superior oblique muscle be tested?

Answer 24

Look medially and down.

Problem: patient won’t be able to look down

Question 25

How can the inferior oblique muscle be tested?

Answer 25

Patient will not be able to look medially and upwards

Question 26

What are the origins of the ophthalmic artery?

Answer 26

Branch of the internal carotid artery

Question 27

What happens if there is an occlusion of the ophthalmic artery?

Answer 27

Retina turns pale as the branches of the ophthalmic artery are end arteries

Question 28

Where does the blood supply of the eye drain to?

Answer 28

Central retinal vein --> Superior ophthalmic vein --> Cavernous sinus

Question 29

What does central retinal vein occlusion cause?

Answer 29

Blurry vision when dehydrated and pressure on the optic disk.

Question 30

What is the function of the lacrimal gland?

Answer 30

Produces fluid which is swept over the eye

Question 31

What is the function of the eyelid?

Answer 31

Protects against injury, dryness and excessive light

Question 32

What area of the eye does the bulbar conjunctiva cover?

Answer 32

Sclera of the eye

Question 33

What area of the eye does the palpebral conjunctiva cover?

Answer 33

Inner lining of eye socket

Question 34

What is conjunctivitis?

Answer 34

Inflammation of the bulbar conjunctiva

Question 35

What is the difference between tarsal gland inflammation and ciliary gland inflammation?

Answer 35

Tarsal gland inflammation is painless swelling of the eyelid. Ciliary gland inflammation is more serious and needs antibiotics to treat

Question 36

What muscle opens the eye?

Answer 36

Levator palpebrae superioris

Question 37

What nerve innervates the levator palpebrae superioris?

Answer 37

CN III (Oculomotor)

Question 38

What muscle closes the eye?

Answer 38

Orbicularis oculi

Question 39

What nerve innervates the orbicularis oculi?

Answer 39

CN VII (Facial)