anatomy of the orbit and the eye

Question 1

what direction does the apex of the orbit point?

Answer 1

posteriorly

Question 2

where is the base of the orbit situated?

Answer 2

anteriorly

Question 3

where is the axis of the eye directed?

Answer 3

anteriorly

Question 4

where is the axis of the orbit directed?

Answer 4

anteriolaterally

Question 5

what bones is the roof (superior wall) of the orbit formed by?

Answer 5

frontal bone
sphenoid (lesser wing)

Question 6

what bones is the floor (inferior wall) of the orbit formed by?

Answer 6

maxilla
palatine
zygomatic

Question 7

what bones is the medial wall of the orbit formed by?

Answer 7

ethmoid
maxilla
lacrimal
sphenoid

Question 8

what bones is the lateral wall of the orbit formed by?

Answer 8

zygomatic
sphenoid (greater wing)

Question 9

what does the optic canal transmit?

Answer 9

optic nerve and ophthalmic artery

Question 10

what does the superior orbital fissure transmit?

Answer 10

lacrimal, frontal, trochlear, oculomotor, nasociliary and abducens nerves

Question 11

what vein does the superior orbital fissure carry?

Answer 11

superior ophthalmic

Question 12

what does the inferior orbital fissure transmit?

Answer 12

zygomatic branch of maxillary nerve
inferior ophthalmic vein
sympathetic nerves

Question 13

where do orbital rim fractures usually occur?

Answer 13

at sutures joining the 3 bones of orbital rim

Question 14

what are the 3 bones of the orbital rim?

Answer 14

maxilla
zygomatic
frontal

Question 15

what is a “blowout” fracture?

Answer 15

partial herniation of the orbital contents through one of its wall

Question 16

what usually causes “blowout” fractures?

Answer 16

blunt force trauma to the eye

Question 17

which walls of the bony orbit are the weakest?

Answer 17

medial and inferior

Question 18

where would the contents herniate into with a blowout fracture?

Answer 18

ethmoid and maxillary sinuses

Question 19

what are the 3 parts of the orbicularis oculi muscle?

Answer 19

palpebral
lacrimal
orbital

Question 20

what is the role of the palpebral part?

Answer 20

gently closes eyelid

Question 21

what is the role of lacrimal part?

Answer 21

involved in the drainage of tears

Question 22

what is the role of the orbital part?

Answer 22

tightly closes the eyelids

Question 23

what nerve innervates the orbicularis oculi muscle?

Answer 23

CN VII (facial nerve)

Question 24

where is the orbicularis oculi muscle located?

Answer 24

deep to skin and connective tissue

Question 25

where are the tarsal plates located?

Answer 25

deep to palpebral region of the orbicularis oculi muscle

Question 26

what are the two tarsal plates?

Answer 26

superior (upper eyelid) inferior (lower eyelid)

Question 27

what are the tarsal plates composed of?

Answer 27

dense connective tissue

Question 28

what does the superior tarsus act as?

Answer 28

attachment site of levator palpebrae superioris

Question 29

what lies in the tarsal plates?

Answer 29

Meibomian glands (tarsal glands)

Question 30

what does Meibomoian glands secrete?

Answer 30

oily lipid substance that slows evaporation of eye's tear film and prevents eyelids sticking together when closed

Question 31

what extends from either tarsus to the orbital margin?

Answer 31

orbital septum

Question 32

what is the role of the orbital septum?

Answer 32

helps prevent spread of infection between superficial and deep parts of the orbit

Question 33

what is the role of the levator palpebrae superioris (LPS) muscle?

Answer 33

elevates the upper eyelid

Question 34

what muscle is LPS attached to?

Answer 34

superior tarsal plate

Question 35

what does the lacrimal gland produce?

Answer 35

lacrimal fluid

Question 36

what is the production of lacrimal fluid a result of?

Answer 36

parasympathetic innervation (CN VII)

Question 37

where does the lacrimal fluid push towards after secretion?

Answer 37

medial angle

Question 38

once in the medial angle where does the lacrimal fluid drain through?

Answer 38

lacrimal puncta