The orbit

Question 1

What forms the roof and floor of the orbit?

Answer 1

Roof= orbital plate of the frontal bone
Floor= maxilla

Question 2

What forms the lateral and medial walls of the orbit?

Answer 2

Lateral wall= greater wing of sphenoid and zygoma

Medial wall= ethmoid and lacrimal bones

Question 3

What does the superior orbital fissure contain?

Answer 3

Oculomotor nerve, trochlear nerve, abducent nerve, branches of opthalmic nerve

Question 4

What does the inferior orbital fissure contain?

Answer 4

Maxillary nerve and sympathetic nerves

Question 5

What does the optic canal contain?

Answer 5

Optic nerve and opthalmic artery

Question 6

What does the lacrimal groove become?

Answer 6

Nasolacrimal canal-> inferior meatus of nasal cavity

Question 7

What is the sclera?

Answer 7

The outer fibrous coat of the eye- the white of the eye
Continuous with cornea and dura
Covered by conjunctiva

Question 8

Describe the cornea

Answer 8

Avascular, richly innervated, transparent
Covered by non-keratinised stratified squamous epithelium
Continuous with conjunctiva

Question 9

What is the middle vascular coat of the eyeball?

Answer 9

Choroid

Question 10

What is the choroid?

Answer 10

Highly vascular middle coat of the eyeball

Continous with iris by the ciliary body

Question 11

What is the ciliary body?

Answer 11

Ciliary processes which project inwards towards the lens, connected by suspensory ligaments
Responsible for changes in lens convexity
Contraction relaxes suspensory ligaments-> increased lens convexity

Question 12

Parasympathetic activation causes what to happen in the eye?

Answer 12

Contraction of ciliary muscles to make lens more convex and adjust for near-sightedness
Sphincter pupillae (circular) contract and constricts pupil

Question 13

Sympathetic activation causes what to happen in the eye?

Answer 13

Dilator pupillae to contract, pupil dilates

Question 14

What is the optic disc?

Answer 14

Blind spot where fibres of optic nerve converge

Question 15

What is the macula lutea and where is it found?

Answer 15

Site of highest visual resolution on retina

Surround fovea centralis

Question 16

What is papilloedema?

Answer 16

Oedema of the vessels entering the eyeball around the optic disc
Caused by increased ICP

Question 17

What is the contents of the eyeball?

Answer 17

Vitreous body (clear gel) behind lens and aqueous humour infront of lens

Question 18

What nerves are involved when focusing on a near object?

Answer 18

Eyes converge (oculomotor), pupils constrict and lenses increase in convexity (Parasympathetic from ciliary ganglion)

Question 19

What is the small elevation on the medial margin of the lower eyelid called?

Answer 19

Lacrimal papilla

Question 20

What is the small orifice in the lacrimal papilla called? Where does it lead?

Answer 20

Lacrimal punctum, leads to lacrimal sac and nasolacrimal duct-> inferior meatus of nasal cavity

Question 21

Whats the palpebral fissure?

Answer 21

Area between eyelids

Question 22

What can lead to sunken eyes?

Answer 22

Cachexia (due to cancer) or severe anorexia

Question 23

What can lead to popping eyes?

Answer 23

Hyperthyroidism

Question 24

What inserts into the skin of the eyelids

Answer 24

Obicularis oculi (palpebral part) and levator palpebrae superioris

Question 25

What are the eyelids strengthened by?

Answer 25

Dense connective tissue= tarsus

Question 26

Where are the tarsal glands and what do they produce?

Answer 26

Found in the tarsus of the eyelids, lubricates edges of the eyelids

Question 27

What is found in the medial corner of the eye?

Answer 27

Lacrimal caruncle and just lateral to it is the plica semiluminaris (vertical fold of conjunctiva)

Question 28

Name the recti and their innervation

Answer 28

Superior, medial and inferior recti= oculomotr | Lateral rectus= abducent

Question 29

Name the other muscles of the eye (not recti)

Answer 29

Superior oblique= trochlear nerve | Inferior oblique= oculomotor nerve

Question 30

Where do the parasympathetic nerves to the eye orginate from?

Answer 30

Pre ganglionic from Edinger-Westphal nucleus in brainstem Travel with oculomotr fibres to ciliary ganglion Post ganglionic fibres travel in short ciliary nerves to eye

Question 31

What would pressure on the oculomotor nerve cause?

Answer 31

Diplopia and ptosis (drooping of eyelids) Large and unresponsive pupil (no PNS innervation) Down and out eye

Question 32

What is myopia?

Answer 32

Focused image falls short of retina, lens too round

Question 33

What is it called when focused image falls short of retina?

Answer 33

Myopia

Question 34

What is hypermetropia?

Answer 34

When image is in focus behind retina | Lens is too flat

Question 35

What does the opthalmic nerve supply?

Answer 35

Sensory to eyeball, lacrimal gland, conjunctiva, eyelids, forehead and nasal mucosa Via lacrimal, nasociliary and frontal branches

Question 36

What is the supply of the lacrimal gland?

Answer 36

Sensory from opthalmic nerve | Parasympathetic from pterygopalatine ganglion

Question 37

What nerves and muscles are involved in the blink reflex?

Answer 37

Sensory efferent from conjunctiva= lacrimal nerve of V1 Brainstem Obicularis oculi closes eyelids= facial nerve (VII)

Question 38

Describe nasociliary nerve

Answer 38

Branch of V1, divides into anterior ethmoidal nerve (ethmoidal sinus) and infratrochlear nerve (skin&mucous membrane of nose and conjunctiva). Also gives off ciliary nerves (sympathetic and sensory to eyeball)

Question 39

What is the blood supply of the retina

Answer 39

Central artery= end artery from opthalmic artery

Question 40

Describe route of blood drainage from retina

Answer 40

Superior and inferior opthalmic veins-? superior orbital fissure-> cavernous sinus inferior orbital fissure-> terygid plexus

Question 41

Name the branches of the opthalmic artery

Answer 41

Ciliary branches, anterior and posteiror ethmoidal and central artery

Question 42

Which branch of the opthalmic nerve is most medial and which is most lateral?

Answer 42

Medial= nasociliary, lateral= lacrimal