Orbits I

Question 1

What bones make up the outer rim of the orbit?

Answer 1

The frontal, zygomatic and maxillary bones.

Question 2

What bones help to form the inside of orbit?

Answer 2

Lacrimal, Ethmoid, Sphenoid and Palatine (in addition to the Frontal, Zygomatic and Maxillary bones which also form the outer rim.)

Question 3

Palpebral fissure

Answer 3

The space between the upper and lower eye lids. The palpebral margins meet at the canthi (the corner/angle of the eye)

Question 4

Horner’s syndrome

Answer 4

Lesion to the superior cervical sympathetic ganglion which results in paralysis in the Tarsal muscle on the affected side.

Patient presents with: Ptosis (eye droop), Meiosis (constricted pupil) and Anhydrosis (lack of sweating)

Question 5

Where is the lacrimal gland located? Where do its ducts drain?

Answer 5

The lacrimal gland is located in the superolateral aspect of the orbit. It’s ducts drain into the superior palpebral fornix.

Question 6

Where does the lacrimal sac sit?

Answer 6

Anterior lacrimal crest fossa of the maxilla

Question 7

Where bone is the optic canal associated with?

Answer 7

Its foramen is located in the body of the sphenoid bone.

Question 8

Where does the levator palpebrae superioris muscle attach?

Answer 8

To the superior tarsus muscle (upper eyelids main component composed of smooth muscle and attaches to the superior tarsal plate). There is also an inferior tarsus muscle.

Question 9

What muscles help close the upper eyelid?

Answer 9

Transverse running fibers of the Orbicularis oculi, specifically the palpebral portion

Question 10

What kind of innervation does the tarsus muscle have?

Answer 10

Sympathetic- opens eye very wide.

Question 11

Lacrimal apparatus

Answer 11

Tears flow inferomedially from the lacrimal gland (superolateral), to the medial canthus, where they drain. Drainage consists of:

Puncta lacrimali (drain opening)
Lacrimal canaliculus (duct)
Lacrimal sac (collection of fluid)
Nasolacrimal duct (drainage to nasal sinus)

Question 12

How does the lower eyelid move?

Answer 12

It doesn’t. It has no muscles of its own.

Question 13

Why do we sniffle when we cry?

Answer 13

The more we cry, the more tears are pumped into the nasolacrimal duct into the nasal sinus

Question 14

Muscles of the orbit (7)

Answer 14

Levator palpebrae superioris (Opens eyelid), SO, SR,MR,LR,IR, IO

Question 15

Anulus Tendineus

Answer 15

A fibrous ring which encircles the junction of the superior and inferior orbital fissures and the optic canal (optic nerve). This is set up so that the muscles are around the nerve but don’t cross it, thereby preventing pinching of the nerve during contraction.

Question 16

Innervation of muscles of eye

Answer 16

All are done by CN III (oculomotor) with the exceptions of LR (CN VI) and SO (CN IV)

Question 17

Function of SR and IR muscles

Answer 17

To pull the eye medially. The orbits are at a 45 degree angle from each other but you want the eyes to look straight. These muscles ensure that.

Question 18

Which muscles DON’T originate from the annulus tendineus?

Answer 18

Superior oblique, Inferior Oblique, Levator Palpebrae Superioris`

Question 19

Inferior division of CN III innervates what?

Answer 19

Inferior oblique, inferior rectus, medial rectus and contain parasympathetic fibers which run to the ciliary ganglion from which the short ciliary nerves branch.

Question 20

What part of CN III innervates the levator palpebrae superioris

Answer 20

Superior branch

Question 21

Actions of all muscles of the orbit

Answer 21

SR (Elevate and Adducts) IR (Depresses and Adducts) SO (down and out) IO (up and out) MR (adducts) LR (abducts)

Question 22

Superior division of CN III innervates what?

Answer 22

levator palpebrae superioris and the superior rectus

Question 23

What hole do the CN III, IV and VI use to enter orbit?

Answer 23

Superior Orbital fissure

Question 24

What comes through the optic canal?

Answer 24

Optic nerve and Ophthalmic artery

Question 25

Nerves on the lateral side of the orbit are…

Answer 25

Lacrimal

Question 26

What nerve starts lateral to optic nerve then crosses over to be medial to it?

Answer 26

Nasociliary nerve

Question 27

Main nasociliary nerve branches

Answer 27

• Communicating branch (they run through short ciliary nerves but DONT synapse there).
• Long Ciliary

Question 28

What functions can short ciliary nerves contain? long ciliary nerves?

Answer 28

Short= sympathetic, parasympathetic, general sensory

Long= sympathetic and general only. NO PARASYMPATHETIC

Question 29

LASSIE

Answer 29

Way to remember the cutaneous branches that come across the eye.

-Lacrimal (LA), Supraorbital (S), Supratrochlear (S), Infratrochlear (I), External Nasal (E)

Question 30

Main 3 branches of ophthalmic nerve

Answer 30

NFL (nasociliary, frontal, lacrimal)

Question 31

Where is the frontal nerve located?

Answer 31

Right on top of everything, when you first enter orbit from above

Question 32

How can you tell short ciliary nerve from long ciliary nerves?

Answer 32

Anything running from the ciliary ganglion to the back of the eye= SHORT CILIARY NERVE

Anything from the nasociliary directly to back of eye= LONG CILIARY NERVE

Question 33

How do sympathetic fibers enter the orbit for their functions?

Answer 33

They travel from the superior cervical ganglion via the internal carotid plexus and then the ophthalmic division of trigeminal (V1). These fibers pass through the ciliary ganglion and enter the eye via the short ciliary nerves. They also reach the eye via the long ciliary nerves.

Here they innervate the dilator pupillae muscle.

Question 34

Central retinal

Answer 34

Important artery which runs through the optic nerve.

Question 35

Venous drainage of the orbit is through the…

Answer 35

Superior and inferior ophthalmic veins, which pass through the superior orbital fissure and enter the cavernous sinus.

Question 36

True or False?

Both sympathetic and parasympathetic fibers synapse in the ciliary ganglion.

Answer 36

FALSE

Only parasympathetic fibers run through the ciliary ganglion. There are no sympathetic ganglion in the head. The highest is the superior cervical sympathetic ganglion in the neck.

Question 37

Cell bodies of the post-ganglionic, parasympathetic fibers to the lacrimal gland are found in what ganglion?

Answer 37

The Pterygopalatine Ganglion

Question 38

The only extraocular muscle which originates from the anterior aspect of the orbit is the…

Answer 38

Inferior Oblique

Question 39

Is the superior oblique located laterally or medially?

Answer 39

Medially

Question 40

Inner layer of the eyelid

Answer 40

Palpebral conjunctiva