Anatomy of the eye and orbit (orbit)

Question 1

Name the 6/7 bones which make up the orbit

Answer 1

frontal, maxillary, zygomatic, lacrimal, ethmoid, sphenoid and (palatine)

Question 2

3 foramen in the orbit

Answer 2

optic foramen
superior orbital fissure
inferior orbital fissure

Question 3

What fissure separates the greater and lesser wings of the sphenoid?

Answer 3

superior orbital fissure

Question 4

What is so important about these 3 foramina in the apex of the orbit?

Answer 4

all neurovascular structures to the orbit must make their way via one of these

Question 5

What makes the medial and inferior orbital walls particularly weak?

Answer 5

closely related to air sinuses

Question 6

3 air sinuses closely related to the orbit

Answer 6

frontal, maxillary and ethmoidal air cells

Question 7

Compare the length of they eyeball and the orbit and what is found in the space?

Answer 7

eyeball is much shorter than the orbit

orbital fat

Question 8

function of orbital fat

Answer 8

cushions globe and support

Question 9

Difference between lids and conjunctiva

Answer 9

lids - skin on outside

conjunctiva - mucous membrane on inside

Question 10

What glands are found in eyelashes which can cause sty’s?

Answer 10

sebaceous glands

Question 11

What muscle a) elevates the eyelid and b) closes the eyelid?

Answer 11

a - levator palpebrae superioris

b - orbicularis occui

Question 12

What is the tarsal plate and its function?

Answer 12

hard plate deep to the orbicularis occuli to keep shape

Question 13

Glands found inside the tarsal plate

Answer 13

meibomian glands

Question 14

What are meibomian glands function?

Answer 14

oily secretory glands for the tear film

Question 15

Conjuctiva

Answer 15

mucous membrane - thin and vascular

covers the inner surface of the eyelids and the sclera

Question 16

Why does the conjunctiva not cover the cornea?

Answer 16

blood vessels often leak and do not want these sitting on top of a transparent cornea

Question 17

Where is the lacrimal gland situated?

Answer 17

superior laterally of the orbit

Question 18

Parasympathetic innervation of the lacrimal gland

Answer 18

facial nerve

Question 19

What does the lacrimal duct open onto?

Answer 19

conjunctival sac

Question 20

How are the tears spread over the cornea?

Answer 20

each blink evenly coats the cornea after the conjunctiva has been coated

Question 21

punctae

Answer 21

tiny hole in the medial part of the eyelid

Question 22

tear drainage pathway

Answer 22

tear –> punctae –> lacrimal sac –> nasolacrimal duct–> inferior meatus

Question 23

What bone does the lacrimal sac lie over?

Answer 23

lacrimal

Question 24

When the orbicularis occuli contracts what happens to the tears?

Answer 24

the lacrimal sac is opened and the tears are sucked in

Question 25

Intrinsic ocular muscles found where?

Answer 25

iris and ciliary body

Question 26

Intrinsic ocular muscles - the 2 functions

Answer 26

control the size of the pupil

alter the curvature of the lens to see objects close up

Question 27

Extrinsic ocular muscles - main function

Answer 27

move the eye

Question 28

Difference in intrinsic and extrinsic muscles origin and attachment

Answer 28

extrinsic - start in orbit and end on sclera

intrinsic - start and end in the eyeball

Question 29

3 intrinsic eye muscles

Answer 29

ciliaris muscle
constrictor pupillae
dilatory pupillae

Question 30

Of the 2 pupillae muscles which is circular and which is radially arranged?

Answer 30

constrictor = circular 
dilator = radial

Question 31

innervation of the 3 intrinsic muscles

Answer 31

ciliaris and constrictor = parasympathetic by oculomotor nerve - CN 3
dilator - sympathetic by nerve plexus around blood vessels

Question 32

Name the 6 extrinsic ocular muscles

Answer 32

rectus - medial, lateral, superior, inferior

oblique - inferior and superior

Question 33

Which muscle has a trochlear?

Answer 33

superior oblique

Question 34

Which muscle arises from the anterior aspect of the orbit?

Answer 34

inferior oblique

Question 35

What do the 4 recti muscles arise from?

Answer 35

posterior apex from an annular fibrous ring

Question 36

What muscles attach to the sclera anteriorly and which posteriorly?

Answer 36

recti = anterior 
oblique = posterior

Question 37

What muscle lies just above the superior rectus?

Answer 37

LPS

Question 38

Where does the LPS attach?

Answer 38

upper eyelid

Question 39

What muscle does the trochlear nerve innervate?

Answer 39

superior oblique - Think Trochlear

Question 40

What muscle does the abducent nerve innervate?

Answer 40

muscle which abducts the eye eg moves it away from the nose which is the LATERAL RECTUS

Question 41

What is the main nerve supply for the enxtrinsic ocular muscles?

Answer 41

oculomotor nerve

Question 42

What 4 cranial nerves are in the orbit?

Answer 42

2,3,4,6

Question 43

What foramen does the optic nerve travel?

Answer 43

optic foramen

Question 44

What does the optic nerve carry?

Answer 44

special sensory fibres

Question 45

What muscle innervates the LPS?

Answer 45

oculomotor nerve

Question 46

Where do the parasympathetic fibres of the oculomotor nerve synapse?

Answer 46

ciliary ganglion in the orbit

Question 47

Where does the trochlear nerve arise?

Answer 47

dorsal part of the midbrain