Orbit and Eye Screencast

Question 1

What are the six bones that make up the orbit?

Answer 1

Frontal, zygomatic, sphenoid, ethmoid, lacrimal, maxilla

Question 2

What bones have orbital plates?

Answer 2

Frontal, ethmoid and maxillary = smoother and flatter areas of bone

Question 3

Why are the maxillary and ethmoid orbital plates likely to fracture?

Answer 3

The bone is thin

Question 4

What structures pass through the optic canal?

Answer 4

The optic nerve and ophthalmic artery

Question 5

What passes through the supraorbital notch?

Answer 5

The supraorbital neurovascular bundle

Question 6

What division does the supraorbital nerve belong to?

Answer 6

CN V1

Question 7

What passes through infraorbital foramen?

Answer 7

Infraorbital neurovascular bundle

Question 8

What division does the infraorbital nerve belong to?

Answer 8

CN V2

Question 9

What shape is the orbit?

Answer 9

Pyramidal = faces anteriorly (has different axis from eyeball)

Question 10

What is the base of the orbit called?

Answer 10

The orbital rim

Question 11

What makes up the apex of the orbit?

Answer 11

The sphenoid bone

Question 12

What is the benefit of the supraorbital margin overhanging the infraorbital margin?

Answer 12

It protects the eye (bones of this area is also thick)

Question 13

What occurs in a blowout fracture?

Answer 13

The thicker bones stay intact but the thinner bones fracture = medial wall and orbital floor are common sites

Question 14

What occurs in a trapdoor fracture?

Answer 14

Soft tissue structures pass through the fractures

Question 15

Where do the bones on the outside of the orbit tend to fracture?

Answer 15

At sutures

Question 16

What makes up the most superficial layer of the eyelid?

Answer 16

The orbicularis oculi = has orbital and palpebral parts

Question 17

What is the orbital part of the orbicularis oculi?

Answer 17

Area around the entire outside of the orbit = carries out tight closure of eye

Question 18

What is the palpebral part of the orbicularis oculi?

Answer 18

Covers the actual eyelid = carries out gentle closure of eye

Question 19

What nerve innervates the orbicularis oculi?

Answer 19

CN VII

Question 20

What makes up the deep layer of the eyelid?

Answer 20

Superior and inferior tarsus, tendon of LPS, lateral and medial palpebral ligaments, orbital septum

Question 21

What are the inferior and superior tarsus?

Answer 21

Fibrous skeleton = thickened bands of connective tissue

Question 22

Where are the lateral and medial palpebral ligaments located?

Answer 22

On either side of the tarsus

Question 23

What is the function of the orbital septum?

Answer 23

Prevents spread of infection from superficial to deep and holds orbital contents in place

Question 24

What is the orbital septum made of?

Answer 24

Tough connective tissue

Question 25

What is the action of the levator palpebrae superioris?

Answer 25

Lifts upper part of the eye

Question 26

What is the superior tarsus muscle?

Answer 26

Slip of smooth muscle that comes off of the levator palpebrae superioris = also called Mueller's muscle

Question 27

What does the superior tarsus muscle do?

Answer 27

Helps widen the eye = under sympathetic control

Question 28

Where are the tarsus glands located?

Answer 28

Within the tarsus = Meibomian glands

Question 29

What do the tarsus glands secrete?

Answer 29

Secrete lipids = cover bottom of eyelids to prevent lacrimal overflow

Question 30

What do the lacrimal glands produce?

Answer 30

Lacrimal fluid (tears)

Question 31

What is the flow of lacrimal fluid?

Answer 31

Wash over eye, pushed towards medial angle by blinking, drains through lacrimal puncta, eventually reaches inferior meatus

Question 32

Where is the lacrimal gland located?

Answer 32

In the lacrimal fossa

Question 33

What innervates the lacrimal glands?

Answer 33

Parasympathetic innervation from CN VII

Question 34

Where do tears collect?

Answer 34

Collect in lacrimal lake = then pass through puncta into canaliculi

Question 35

What is the first part of the nasolacrimal duct?

Answer 35

Lacrimal sac

Question 36

How many extra-ocular muscles are there?

Answer 36

7 = 4 rectus muscles, 2 oblique muscles and the levator palpebrae superioris

Question 37

Where do the rectus muscles pass?

Answer 37

Run from orbit straight onto the eyeball

Question 38

What are the rectus muscles?

Answer 38

Superior and inferior, medial and lateral

Question 39

What are the oblique muscles?

Answer 39

Superior and inferior = insert onto eyeball at oblique angle and attach more posterior than rectus muscles

Question 40

What does the superior oblique muscle pass through?

Answer 40

The trochlea = loop of connective tissue which acts as a pulley to turn the muscle

Question 41

Where do the rectus muscles originate from?

Answer 41

Common tendinous ring (annulus) = anterior to optic canal

Question 42

Where do the rectus muscles insert on to?

Answer 42

The sclera

Question 43

Where does the superior oblique muscle originate from?

Answer 43

The sphenoid bone

Question 44

Where does the inferior oblique originate from?

Answer 44

Orbital plate of maxilla

Question 45

Where does the levator palpebrae superioris originate from and insert onto?

Answer 45

``` Origin = lesser wing of sphenoid Insertion = skin and superior tarsus ```

Question 46

What nerve innervates the lateral rectus muscle?

Answer 46

CN VI

Question 47

What muscle does CN IV innervate?

Answer 47

Superior oblique muscle

Question 48

What muscles does CN III innervate?

Answer 48

Inferior oblique, superior and inferior rectus, medial rectus, levator palpebrae superioris