1.10: Instant Anatomy Tutorial

Question 1

Where is the orbital septum?

Answer 1

Just posterior to the to orbicularis orbis muscle

Question 2

What is orbital cellulitis?

Answer 2

This is inflammation posterior to the septum and is sight threatening

Question 3

What is the opposite of orbital cellulitis?

Answer 3

Pre-septal cellulitis

Question 4

What are the two types of conjunctiva? Where are they found?

Answer 4

Palpebral conjunctiva lines the inner surface of the eyelid Bulbar conjunctiva lines the eyeball

Question 5

What are the parts of the orbicularis orbis muscles?

Answer 5

Orbital Part = Closes eye tightly Palpebral Part = Involved in normal blinking

Question 6

What is ptosis?

Answer 6

Drooping of the upper eyelid

Question 7

Fill in the blanks: The XXXX muscle assists the XXXX in elevating the top eyelid This requires XXXX innervation and may be compromised in XXXXXX This leads to ptosis

Answer 7

The Mullers muscle assists the elevator in elevating the top eyelid This requires sympathetic innervation and may be compromised in Horners Syndrome This leads to ptosis (top eyelid droop)

Question 8

Fill in the blanks: The tear film has XXXXX properties due to the action of lysozyme

Answer 8

The tear film has antibacterial properties due to the action of lysozyme

Question 9

What nerve is required for tear production?

What supplies sensory to the lacrimal gland?

Answer 9

Facial

Trigeminal (V2) does sensory

Question 10

Out of the two conjunctiva, which is more vascular?

Answer 10

The Palpebral is more vascular than the bulbar conjunctiva (Bulbar covers eye - must be able to let light through)

Question 11

Describe the features of the palpebral conjunctvia?

Answer 11

Follicles Papillae Goblet cells to secrete part of the tear film

Question 12

Name the layers of the cornea?

Answer 12

Epithelium Bowman’s Membrane Stroma Descemet’s membrane Endothelium

Question 13

What is the outermost part of the lens called? Innermost part?

Answer 13

Outermost = Cortex Innermost = Nucleus

Question 14

What is the lens attached to? What is it attached by?

Answer 14

Attached to the ciliary body Attached by connective tissue called Zonular Fibres Collectively referred to as suspensory ligaments

Question 15

What holds the lens in place?

Answer 15

Suspensory Ligaments (Composed of zonular fibres)

Question 16

What is the uvea? Vascular or Avascular?

Answer 16

Middle layer of the eye Composed of the Iris, Ciliary body and Choroid Vascular Layer

Question 17

Function of the uvea?

Answer 17

Role in absorbing reflected light of the eye Provides nutrients to many structures of the eye

Question 18

What is the aqueous humour?

Answer 18

Transparent, gel-like fluid Produced by filtration of blood at ciliary processes

Question 19

Describe the circulation of aqueous humour?

Answer 19

Flows from the posterior chamber to anterior chamber (of anterior segment) Drains into canal of schlemm

Question 20

Does the aqueous humour have a high or low protein content? Why?

Answer 20

Low protein content To allow it to be transparent

Question 21

Describe accommodation?

Answer 21

This is changing the lens to allow light to come into focus on the retina This reflex is stimulated by having a blurred image on the retina Causes pupillary constriction and contraction of the ciliary muscle

Question 22

Describe the third cranial nerve? Palsy?

Answer 22

The Oculomotor Controls all the ocular muscles except lateral rectus and superior oblique Plays a part in accommodation Palsy: Down and out with ptosis (eye lid droop)

Question 23

Describe the fourth cranial nerve? Palsy?

Answer 23

Trochlear Nerve Innervates Superior Oblique Palsy: Unable to fully depress the eye when in adduction

Question 24

Describe the sixth cranial nerve? Palsy?

Answer 24

Abducens Innervates lateral rectus Inability to adduct eye - causes it to stay medially

Question 25

Where do the ocular muscles all come from?

Answer 25

The common tendinous ring

Question 26

In the retina, where is the highest density of cones?

Answer 26

Fovea

Question 27

What cells (in the retina) give rise to the optic nerve?

Answer 27

Ganglion Cells

Question 28

Describe venous drainage of the eye?

Answer 28

Drained by superior ophthalmic vein, inferior ophthalmic vein and central retinal vein These drain into the cavernous sinus

Question 29

Describe sensory supply to the eye?

Answer 29

Long and short ciliary nerves become part of the nasociliary nerve of the trigeminal Cornea has a rich supply of free nerve endings Retina has photoreceptors which respond to light only