Orbit and the Eye

Question 1

Identify the bones in the bony orbit

Answer 1

Question 2

Identify features of the bony orbit

Answer 2

Question 3

What is the apex of the bony orbit?

Answer 3

Optic canal

Question 4

What are the sides of the orbital rim?

Answer 4

Superior, inferior, medial and lateral orbital margins

Question 5

What kind of fracture can affect the medial wall and orbital floor?

Answer 5

Orbital blowout fracture

Question 6

Which muscle forms the external layer of the eyelid?

Answer 6

Orbicularis oculi

Question 7

What are the parts of the orbicularis oculi?

Answer 7

Orbital and palpebral

Question 8

What are tarsal glands embedded in tarsi responsible for?

Answer 8

Lipid secretion

Question 9

The iris is covered by conjunctiva/cornea and the sclera and lower eyelid is covered by conjunctiva/cornea

Answer 9

Cornea

Conjunctiva

Question 10

What is the junction between cornea and sclera better known as?

Answer 10

The limbus

Question 11

Outline the path of lacrimal fluid in the eye

Answer 11

Produced by lacrimal gland before washing over eye and being pushed toward the medial angle. Drain through lacrimal punctae before reaching inferior meatus

Question 12

Which nerve provides parasympathetic innervation to the lacrimal gland?

Answer 12

CN VII (facial)

Question 13

What are the three layers of the eye?

Answer 13

Fibrous

Uvea (vascular layer)

Retina (photosensitive)

Question 14

What are the two parts of the fibrous layer?

Answer 14

Sclera and cornea

Question 15

What are the three parts of the uvea?

Answer 15

Iris

Ciliary body

Choroid

Question 16

What divides the eye into anterior and posterior segments?

Answer 16

Lens

Question 17

The anterior segment contains vitreous/aqueous humour while the posterior segment contains vitreous/aqueous humour

Answer 17

Anterior contains aqueous while posterior contains vitreous

Question 18

Outline the circulation of aqueous humour

Answer 18

Ciliary body secretes aqueous which nourishes lens within posterior chamber then cornea in anterior chamber. Passes into scleral venous sinus (canal of Schlemm) and is reabsorbed

Question 19

What is the main arterial supply to the eye and what is it a branch of?

Answer 19

Ophthalmic artery - branch of internal carotid

Question 20

The central artery of the retina is wholly encapsulated by what?

Answer 20

Optic nerve

Question 21

The majority of venous drainage of the eye comes from which vein?

Answer 21

Superior ophthalmic vein

Question 22

What is the importance of the danger triangle of the face?

Answer 22

Bacteria in this area can enter the venous system which can enter the cavernous sinus and meninges

Question 23

What is found within the fundus?

Answer 23

Optic disc

Macula

Fovea (centre of macula)

Question 24

The optic disc is the point of CN III formation. True/false?

Answer 24

False - site of CN II formation (optic nerve)

Question 25

Where is the blind spot of the eye? Why?

Answer 25

Optic disc - there are no photoreceptors

Question 26

The fovea within the macula has the greatest density of cones/rods

Answer 26

Cones

Question 27

From anterior to posterior, what are the layers of the retina?

Answer 27

Axons of ganglion cells Ganglion cells Photoreceptors

Question 28

Complete ischaemia of the central artery of the retina can lead to what?

Answer 28

Monocular blindness

Question 29

What are the 7 extraocular muscles of the eye?

Answer 29

Superior rectus Inferior rectus Medial rectus Lateral rectus Superior oblique Inferior oblique Levator palpebrae superioris

Question 30

Where do all rectus muscles originate and insert?

Answer 30

Originate from common tendinous ring and insert onto sclera

Question 31

What is the somatic motor innervation of the extraocular muscles?

Answer 31

LR6 - Lateral rectus CN VI SO4 - Superior oblique CN IV AO3 - All others CN III

Question 32

What are the only two eyeball muscles not to have a secondary movement?

Answer 32

Medial and lateral rectus

Question 33

The lateral rectus muscle can only abduct/adduct the eyeball and bring line of gaze into the same plane as superior and inferior rectus/oblique

Answer 33

Abduct Rectus

Question 34

When in abduction, the superior rectus can only elevate/depress while the inferior rectus can only elevate/depress

Answer 34

Elevate Depress

Question 35

The medial rectus can only abduct/adduct the eyeball and bring line of gaze to the same plane as superior and inferior rectus/oblique

Answer 35

Adduct Oblique

Question 36

When in adduction, the superior oblique can only elevate/depress while the inferior oblique can only elevate/depress

Answer 36

Depress Elevate

Question 37

Pure elevation of the eyes is carried out by which muscles acting synergistically?

Answer 37

Superior rectus and inferior oblique

Question 38

Pure depression of the eyes is carried out by which muscles acting synergistically?

Answer 38

Superior oblique and inferior rectus