Eye Anatomy

Question 1

What is the fibrous layer that supports the eyelids?

Answer 1

Tarsal plate

Question 2

What glands lie within the tarsal plate?
What do they do?
What pathology can develop in them?

Answer 2

Meibomian glands
Secrete oil into tear film to stop evaporation
Chalazion- granulomatous painless swelling

Question 3

Which two muscles are responsible for eyelid movement? Which cranial nerves innervate them?

Answer 3

Orbicularis oculi- cranial nerve 7. Closes eye.

Lavatory palpebrae- CN3. Opens eye.

Question 4

What is the junction of cornea and conjunctiva called?

Answer 4

Limbus

Question 5

What is the thickening of the conjunctiva near the medial canthus called?

Answer 5

Semilunar fold

Question 6

Name the tear glands
Describe their locations
Describe the drainage system of the eye

Answer 6

Accessory glands- produce most of the tears, located within eyelid and conjunctiva.
Lacrimal gland- located superolateral to eye. Responsible for reflexive tearing.

Drain out through small pores called lacrimal puncta on the medial lids. Flow down lacrimal tubing into inferior turbinate (nose).

Question 7

In which situation would a lid laceration be concerning?

Answer 7

If it occurs in the nasal quadrant it can cause damage to tear drainage.

Question 8

What structure is continuous with the sclera?

Answer 8

Cornea

Question 9

What structure is formed by the sclera at the posterior of the eye?

Answer 9

Optic sheath

Question 10

Name the three chambers of the eye and what structures they lie between

Answer 10

Anterior: cornea and iris
Posterior: iris and lens
Vitreous: Lens and retina

Question 11

What is the purpose of aqueous humour?

Answer 11

Nourishes avascular cornea and lens

Question 12

Describe the layers of the cornea

Answer 12

From top to bottom: 
Epithelium- protective
Bowman’s layer
Stroma- damage here can cause scarring
Descemet’s membrane- basal lamina 
Endothelium

Question 13

What is the purpose of the corneal endothelium?

What happens if damaged?

Answer 13

Pump to keep cornea dehydrated
If damaged can cause corneal oedema.
Cells don’t regenerate- too much damage means too few cells and need for corneal transplant

Question 14

Describe the drainage of aqueous humour

Answer 14

Drains through anterior chamber angle via trabecular meshwork into Schlemms Canal.

Question 15

What components collectively make up the uvea?

Answer 15

Iris, ciliary body, choroid plexus

Question 16

What are the two functions of the ciliary body?

Answer 16

Controls shape of lens

Secretes aqueous fluid

Question 17

What structures within the ciliary body change the shape of the lens?

Answer 17

Zonular fibres

Question 18

Describe the structure and function of the choroid plexus

Answer 18

Bed of blood vessels living under the retina
Supplies nutrition to the outer 1/3 of the retina, which contains the rods and cones. Retinal detachments can seperate retina from choroid plexus and cause death of the rods and cones.

Question 19

Describe the structure of the lens

Answer 19

Peanut M&M.

Capsule, cortex, nucleus.

Question 20

What are the three types of cataracts?

Answer 20

Nuclear
Cortical
Subcapsular

Question 21

What is the name for the difficulty “rounding out” the lens that commonly occurs after age 40, causing trouble reading?

Answer 21

Presbyopia

Question 22

Describe the four layers of the retina innermost to outermost

Answer 22

Ganglion nerves- continuous with optic nerve
Photoreceptors
Choroid plexus- part of uvea
Optic sheath- continuous with sclera

Question 23

What is the macula?

Answer 23

Pigmented area of retina responsible for central vision

Question 24

Describe the location, function, and nutritional supply of the fovea

Answer 24

Central macula
Small pit involved in extreme central vision
Nutrition comes entirely from choroid- very vulnerable to retinal detachment

Question 25

Name the seven bones that form the orbit

Answer 25

``` Frontal Ethmoid Lacrimal Maxillary Palatine Zygomatic Sphenoid ```

Question 26

What is the orbital apex? What Two important structures lie within it? What surrounds these structures? What are some pathologies are associated with injury here?

Answer 26

Posterior end of pyramid shaped orbit at the craniofacial junction where four walls of orbit meet. Optic foramen, superior orbital fissure. Annulus of Zinn Orbital apex syndrome- damage to orbital apex. Involves optic nerve. Ptosis, blindness, and opthalmoplegia. (II, III, IV, V1, VI) Cavernous sinus syndrome- orbital apex syndrome + more trigeminal involvement Rochon-Duvigneaud syndrome- SOF damage. No blindness.

Question 27

Where does the retina get it’s nutritional supply?

Answer 27

Anterior 2/3 from retinal vessels, posterior third from choroid.

Question 28

Which is the only ocular muscle that doesn’t originate at the orbital apex?

Answer 28

Inferior oblique

Question 29

Describe the regions of the conjunctiva

Answer 29

Bulbar- over sclera on eyeball Forniceal- Fornix is the doubling back Palpebral (marginal/tarsal/orbital)

Question 30

What type of conjunctival injection is associated with inflammation of deep structures?

Answer 30

Ciliary flush/mixed

Question 31

What conditions commonly cause follicular inflammation?

Answer 31

Adenovirus Chlamydiae Herpes simplex Allergic

Question 32

What can cause inflammation of the papillae?

Answer 32

Often chronic- allergic/mechanical irritation conjunctivitis Anything really

Question 33

Describe the classic features of adenovirus conjunctivitis

Answer 33

Abrupt onset Unilateral=>bilateral Follicles, diffuse hyperaemia, mucoserous discharge, Preauricular adenopathy Can get severe- keratitis with photophobia and ++pain. Pseudomembrane formation Can have second phase corneal infiltrates

Question 34

Name four common causative agents of bacterial conjunctivitis

Answer 34

Staph aureus Staph epidermis Strep pneumoniae Haemophilus influenzae

Question 35

Name the 6 extraocular muscles responsible for eye movement and their innervation

Answer 35

``` superior rectus - CNIII inferior rectus - CNIII medial rectus - CNIII lateral rectus - CNVI inferior oblique - CNIII superior oblique - CNIV ```

Question 36

Name the 6 extraocular muscles responsible for eye movement and their actions

Answer 36

superior rectus - elevation and med rotation inferior rectus - depression and lat rotation medial rectus - adduction lateral rectus - abduction inferior oblique - elevation, lat rotation and abducts (up n out) superior oblique - depress, med rotation and abducts (down n out)

Question 37

Where do the 4 rectus muscles originate from and attach to?

Answer 37

Tendinous ring, sclera

Question 38

What bony structure down the s.oblique travel thru?

Answer 38

Trochlear