Orbit

Question 1

What are the 3 components of the RIM of the orbit?

Answer 1

1. Frontal (roof)
2. Zygomatic (lateral)
3. Maxilla (floor)

Question 2

What are the 4 BONES inside the orbit?

Answer 2

1. Lacrimal - medial –> fossa for LACRIMAL SAC
2. Ethmoid Bone - medial –> extremely thin = lamina papyracea
3. Sphenoid (posterior and lateral)
4. Palatine bone (small medial portion posteriorly)

Question 3

The boundaries of the orbit form a pyramid shape. Describe the:

1. Base
2. Apex
3. Superior Wall
4. Medial Wall
5. Inferior Wall
6. Lateral Wall

Answer 3

1. Base = RIM of the orbit
2. Apex - OPTIC CANAL
3. Superior Wall - FRONTAL BONE
4. Medial Wall - ( ethmoid, lacrimal, frontal, maxilla, sphenoid)
5. Inferior Wall - maxilla, portions of zygomatic, palatine
6. Lateral - Zygomatic and sphenoid

Question 4

What protects and aids in lubrication of the eye and has 7 layers?

Answer 4

The palpebrae

Question 5

List and Describe the 7 layers of the Palpebrae. FROM EXTERNAL TO INTERNAL

Answer 5

1. Skin (sweat glands + sebaceous glands, sebaceous glands of eyelashes = Ciliary Glands)
2. Subcutaneous Loose Connective Tissue
3. Muscular layer (palpebral portion of Orbicularis Oculi)
4. Submuscular Loose Connective Tissue (where CN & for Orbicularis Oculi is)
5. Tarsal Plate
   - Levator Palpebrae Superioris Muscle
   - Tarsal Muscle (sympathetically controlled)
6. Tarsal Gands - help form tight seal when eyelids are closed
7. Palpebral Conjuctive - mucous membrane inside of eyelid

Question 6

What is the space called between the upper and lower palpebrae?

Answer 6

Palpebral Fissure

-bounded by the upper and lower palpebral margins. Palpebral margins meet at the canthi (angles).

Question 7

How does one acquire Horner’s Syndrome? What are the symptoms?

Answer 7

Lesion to the superior cervical sympathetic ganglion, with resulting paralysis in the Tarsal muscle on the affected side.

Patient presents with:
Ptosis – eyelid cannot fully open
Meiosis – pupil shrinks
Anhydrosis – lack of sweat, flushing of the face

Question 8

What are the medial and lateral angles of the eye?

Answer 8

Medial and Lateral Canthus

Question 9

What is the LARGE medial angle of the eye when open?

Answer 9

Lacrimal Lake

Question 10

What is the fleshy elevation within the Lacrimal Lake called? What does it contain that usually appears during sleep?

Answer 10

LACRIMAL CARUNCLE

• contains sweat glands and sebaceous glands and cilia
• is responsible for yellowish-white secretions during sleep

Question 11

What is the Plica Semilunaris? What two structures does it separate?

Answer 11

the connective tissue band found just lateral to the lacrimal caruncle.

• homologous to the nictitating membrane (“third eyelid”) seen in many other animals.
• The plica separates the sclera from the lacrimal lake.

Question 12

What provides lubrication for the anterior surface of the eye?

Answer 12

Lacrimal Apparatus

Question 13

Where is the Lacrimal Gland located?

Answer 13

In the SUPEROLATERAL aspect of the orbit, in the lacrimal fossa of the FRONTAL bone

Question 14

Where do the ducts from the lacrimal gland drain into?

Answer 14

Superior palpebral fornix (located at the junction of the palpebral and orbital conjunctiva).

• Tears secreted collect in the superior fornix of the upper lid, and pass over the eye surface (aided by blinking)
• only the upper eyelid has ability to raise and close

Question 15

What are some of the components of the watery solution produced by the Lacrimal Gland?

Answer 15

1. Lysozyme - bacteriocidal enzyme
2. Nutrients
3. Dissolved Oxygen

Question 16

Describe the parasympathetic innervation to the lacrimal gland.

Answer 16

1. Pre-ganglionic secretomotor fibers travel in GREATER PETROSAL N.
2. to the NERVE OF THE PTERYGOID CANAL
3. synapse in the PTERYGOPALATINE GANGLION
4. post-ganglionic fibers course with the MAXILLARY NERVE (V2)
5. to the Zygomatic Branch
6. Connects the LACRIMAL N. (V1) to the
7. LACRIMAL GLAND

Question 17

Describe the SYMPATHETIC innervation to the lacrimal gland.

Answer 17

1. pre-ganglionic fibers originate in upper thoracic cord
2. travel in the SYMPATHETIC CHAIN
3. synapse in SUPERIOR CERVICAL GANGLION
4. Post-ganglionic fibers follow the Carotid Plexus
5. to the DEEP PETROSAL N.
6. forming the NERVE of the PTERYGOID CANAL
7. pass through the pterygopalatine ganglion to LACRIMAL GLAND
   * ** don’t synapse in the ganglion

Question 18

How to tears flow? What are the 4 areas that they pass/drain in?

Answer 18

Tears flow from the SUPEROLATERALLY placed lacrimal gland–> inferomedially to the medial canthus of the eye, where they drain:

Puncta lacrimali – drain opening
Lacrimal canaliculus - duct
Lacrimal sac – collection of fluid
Nasolacrimal duct – drainage to nasal sinus –> under the inferior Concha (inferior meatus)

Question 19

Describe the GENERAL SENSORY innervation to the Lacrimal Gland

Answer 19

Opthalmic division of Trigeminal (V1) via the Lacrimal N. to the gland and its tissues

Question 20

What 4 muscles of the eye originate in the ANNULUS TENDINEUS? What is the annulus tendineus?

Answer 20

• it is the common tendinous ring
  1. Superior Rectus
  2. Medial Rectus
  3. Inferior Rectus
  4. Lateral Rectus

Question 21

Which muscle functions to raise the eyelid? What is its

Origin, Insertion and Innervation?

Answer 21

Levator Palpebrae Superioris
O: lesser wing of sphenoid, anterior to Optic Canal
I: TARSAL PLATE
N: Oculomotor N. (3) - SUPERIOR DIVISION

Question 22

What muscle elevates and adducts the eye? (medially rotates) What is its
Origin, Insertion and Innervation?

Answer 22

Superior Rectus
O: annulus tendineus
I: Superior aspect of eye (behind corneosceral junction)
N: Oculomotor N (3) - SUPERIOR DIVISION

Question 23

What muscle depresses and adducts the eye? (laterally rotates) What is its
Origin, Insertion and Innervation?

Answer 23

Inferior Rectus
O: annulus tendineus
I: inferior aspect of eye (behind the corneosceral junction)
N: Oculomotor N (3) - INFERIOR DIVISION

Question 24

What muscle ONLY ADducts the eye? What is its

Origin, Insertion and Innervation?

Answer 24

MEDIAL Rectus
O: annulus tendineus
I: medial aspect of eye behind corneoscleral junction
N: Oculomotor N (3) - INFERIOR DIVISION

Question 25

What muscle ONLY ABducts the eye? What is its | Origin, Insertion and Innervation?*

Answer 25

LATERAL Rectus O: annulus tendineus I: lateral aspect of eye behind corneoscleral junction N: Abducent N. (6)

Question 26

What muscle ELEVATES and ABDUCTS the eye? (laterally rotates) What is its Origin, Insertion and Innervation? Up and Out*

Answer 26

Inferior Oblique O: anterior floor of orbit, lateral to nasolacrimal duct I: lateral aspect of eye, deep to LATERAL RECTUS muscle N: Oculomotor N. (3) - INFERIOR DIVISION

Question 27

What muscle DEPRESSES and ABDUCTS the eye? (medially rotates) What is its Origin, Insertion and Innervation? Down and out *

Answer 27

IO UO, SO DO Superior Oblique O: Body of sphenoid, above optic canal, medial to superior rectus I: PASSES THROUGH THE TROCHLEA, deep and lateral to superior rectus N: TROCHLEAR N. (4)

Question 28

Which muscles have a medial pull on the eye?

Answer 28

Inferior and Superior Rectus + Medial Rectus --> opposite function of IO UO SO DO (inferior and superior oblique = ABduct)

Question 29

What muscles do not originate from the Annulus Tendineus?

Answer 29

Muscles that do NOT originate from the anulus tendineus: Superior oblique: Sphenoid Inferior oblique: Maxilla Levator palpebrae superioris: Sphenoid

Question 30

Which muscles are the adductors of the eye?

Answer 30

1. Superior Rectus (elevate) 2. Inferior Rectus (depress) 3. Medial Rectus

Question 31

Which muscles are the ABductors of the eye?

Answer 31

1. Superior Oblique (medially rotates) 2. Inferior Oblique (laterally rotates) 3. LATERAL RECTUS

Question 32

What is the function of the Optic Nerve?

Answer 32

Optic nerve (CN II) enters the orbit via the optic canal (with ophthalmic artery). --It conveys sensory INFORMATION (vision) from the retina to the CNS. It is covered by meninges, and is the largest nerve in the orbit

Question 33

Which nerve of the orbit supplies the SENSORY INNERVATION to the orbit and eye? What are its three primary branches?

Answer 33

Opthalmic Division of Trigeminal nerve (CN V1) - enters through the superior orbital fissure and then divides into three primary branches: NFL 1. Lacrimal nerve 3. Frontal nerve a - Supraorbital b - Supratrochlear 3. Nasocilliary

Question 34

What are some important features of NFL (Nasocilliary, Frontal, and Lacrimal Nerves)

Answer 34

1. Nasocilliary has several branches (next notecard) - short & long Ciliary Nerves - Posterior and Anterior Ethmoidal - Infratrochlear Nerves 2. Frontal - splits into - supraorbital - upper eyelid and skin over eye (scalp) - supratrochlear - medial canthus and bridge of nose 3. Lacrimal - post-ganglionic parasympathetics and sympathetic fibers to lacrimal gland (after receiving fibers from Zygomaticotemporal branch of V2)

Question 35

Sensory fibers that enter the eye via the SHORT CILIARY NERVEs synapse in the ganglia. TRUE OR FALSE

Answer 35

FALSE - they exit without synapsing from the communicating branch to the ciliary ganglion (part of Nasocilliary nerve)

Question 36

What is the terminal branch of the Nasociliary Nerve?

Answer 36

INFRATROCHLEAR | - supplies bridge and superior aspect of nose

Question 37

What innervates the eye (cornea, sclera) by running directly to the back of the eyeball? What nerve branch of V1 does it originate from?

Answer 37

1. Long Ciliary nerves | - from the Nasocilliary N. of V1

Question 38

What are the cutaneous branches of the eye?

Answer 38

LaSSIE = (CUTANEOUS BRANCHES OF THE EYE) 1. Lacrimal branch laterally, 2. Supraorbital 3. Supratrochlear 4. Infratrochlear 5. External Nasal

Question 39

Which nerve of the the Nasocilliary Branch of V1 conveys both sympathetic, parasympathetic and sensory innervation to the eye? Which conveys only sympathetic and sensory?

Answer 39

The short ciliary nerve - supply all three modalities to the eye (parasympathetic, sympathetic, and sensory). The LONG ciliary nerve

Question 40

What innervates the floor of the orbit and the upper lip? Where does it enter? What branches does it give off before terminating in the Infraorbital Foramen?

Answer 40

Maxillary branch of Trigeminal (v2) - enters via Inferior Orbital Fissure - gives off Zygomatic Branch before enters infraorbital canal - terminates through Infraorbital Foramen as the INFRAORBITAL NERVE?

Question 41

What do parasympathetic fibers from Oculomotor Nerve do?

Answer 41

Parasympathetic fibers - from the Edinger-Westphal nucleus of the oculomotor nerve (CN III). 1 - cause constriction of the pupil (sphincter pupillae m.) 2 - allow the eye to focus on near objects (contraction of the ciliary muscle) --> accommodation of lens

Question 42

How do sympathetic fibers reach the eye? What ganglia do they pass through and which ganglia do they synapse at? What to they innervate? What are the two ways that sympathetics can reach the eye?

Answer 42

** from the superior cervical ganglion (SYNAPSE HERE)** via the internal carotid plexus and then the ophthalmic division of trigeminal (V1). - pass through the ciliary ganglion (DONT SYNAPSE) and enter the eye via the short ciliary nerves. - They innervate the dilator pupillae muscle (dilate pupil). - Sympathetic fibers also reach the eye via long ciliary nerves.

Question 43

Where does the Opthalmic Artery enter the eye? What is it a direct branch off of and what does it supply?

Answer 43

- enters the orbit via the optic canal. | - supplies blood to the orbit including the eye itself (lacrimal gland, eyeball, all muscles)

Question 44

What are the branches of the Othalmic Artery?

Answer 44

1. Short and Long Posterior Ciliary A. 2. Lacrimal A. - recurrent branch to eyeball = anterior ciliary a. 3. Posterior Ethmoidal 4. Supraorbital (foreheard and scalp; exits the orbit to the forehead and scalp) 5. Anterior Ethmoidal 6. Supratrochlear 7. Dorsal Nasal A.

Question 45

What is the venous drainage of the eye?

Answer 45

- Superior and Inferior Ophthalmic Veins | - which pass through the superior orbital fissure and enter the cavernous sinus.

Question 46

What is the venous drainage from the retina?What are veins in the eye called?

Answer 46

Central Vein of the Retina - veins in the eye = Vorticose Veins