Orbit & Eye

Question 1

What is in the bony orbit?

Answer 1

Zygomatic, ethmoid, maxillary, frontal, lacrimal, palatine

Question 2

What is a “blowout” fracture?

Answer 2

result in bleeding into maxillary sinus; may entrap inferior rectus (restricted upward gaze) or inferior oblique muscle and/or lacerate the infraorbital n. (sensory loss on lower eyelid & maxilla)

Question 3

What is a medial orbital fracture? What does in impact?

Answer 3

impact the ethmoid&raquo_space; sphenoid sinus; can entrap
medial rectus (restricted lateral gaze)

Question 4

What are the structures of the eyelids?

Answer 4

Skin, loose CT, muscular layer, tarofascial layer, conjunctiva

Question 5

What lubricates the eye?

Answer 5

Lacrimal gland along with accessory lacrimal glands

Question 6

The lacrimal gland’s innervation is…

Answer 6

GSA, GVE parasympathetics via CN VII, and GVE sympathetics via T1-T4

Question 7

Where is the collecting apparatus situated?

Answer 7

Medial canthus

Question 8

What does sympathetics control in the eye?

Answer 8

Blood

Question 9

What does parasympathetics control in the eye?

Answer 9

Secretion
Injury to parasympathetics -> dry eye

Question 10

The suspensory ligament of Lockwood…

Answer 10

Holds eyeball inside eye

Question 11

What are the internal structure of the eye?

Answer 11

1. Fibrous layer
2. Vascular layer
3. Nervous layer

Question 12

What is the fibrous layer continuous with?

Answer 12

Dura

Question 13

What does the fibrous layer make up?

Answer 13

Sclera

Question 14

What is the sclera?

Answer 14

Covers 5/6 of the eye, opaque, lamina cribrosa, major attachment of eye muscles

Question 15

What is continuous with the sclera?

Answer 15

Cornea, transparent

Question 16

What does the vascular layer make up?

Answer 16

Choroid

Question 17

What is the choroid continuous with?

Answer 17

Arachnoid + pia

Question 18

What is the choroid?

Answer 18

Covers about 5/6 of the eye, has the optic nerve within

Question 19

If we block scleral venous sinus, what can occur?

Answer 19

Glaucoma

Question 20

Where is the ciliary body?

Answer 20

Vascular layer

Question 21

What is the ciliary body?

Answer 21

• from ora serrata to scleral spur
• ciliary process and zonular fibers
• secretes aqueous humor
• ciliary muscle
• scleral venous sinus
• anterior and posterior chambers

Question 22

How is the lens anchored?

Answer 22

Zonular fibers

Question 23

What is lens?

Answer 23

• found at the junction of the anterior and posterior compartments
• anterior surface contacts the iris
• posterior surface contacts the vitreous body
• ciliary processes and zonular fibers
• cataract

Question 24

The action of ciliary muscle when relaxed is…

Answer 24

Big opening, tight zonula fibers, lens is flat & skinny

Question 25

The action of ciliary muscle when contracted is...

Answer 25

Small opening, slack zonula fibers, lens is rounded & fat

Question 26

What is within the iris?

Answer 26

Sphincter pupillae (CN III) Dilator pupillae (sympathetics, T1-T4)

Question 27

What is the function of the iris?

Answer 27

Split into anterior & posterior compartments

Question 28

Pupil is...

Answer 28

Empty!

Question 29

When are dilator pupillae most active?

Answer 29

Scared, sympathetics, dark room

Question 30

When are constrictor pupillae most active?

Answer 30

Surrounded by light

Question 31

What is in the nervous layer?

Answer 31

Retina, macula layer, optic disc

Question 32

What does the retina contain?

Answer 32

* contains pigmented epithelium and photoreceptive cells * neural and non neural parts * from ora serrata to optic disc

Question 33

What is macula layer?

Answer 33

* an area of the retina with a high concentration of photoreceptors * fovea centralis - area of highest visual acuity, a tea cup-like depression

Question 34

What is optic disc?

Answer 34

* where optic nerve fibers leave the eye * no photoreceptors here = blind spot * entry/exit of the central retinal vessels

Question 35

If the macula is flattened, what occurs?

Answer 35

Papilledema

Question 36

What is the vitreous body?

Answer 36

 gel-like mass that fills the posterior chamber  functions in refraction of light and maintains the shape of the globe  hyaloid canal

Question 37

What is the vascular supply of the eye?

Answer 37

Ophthalmic artery

Question 38

What are the branches of the ophthalmic artery?

Answer 38

* central artery of the retina * muscular * ciliary * lacrimal * supraorbital * anterior and posterior ethmoidal * meningeal * supratrochlear and dorsal nasal

Question 39

What is amaurosis fugax?

Answer 39

Vision loss in one eye, fleeting blindness Sign of impending stroke

Question 40

What is the venous drainage of the eye?

Answer 40

* Superior ophthalmic vein * Inferior ophthalmic vein * Infraorbital vein * Central vein of the retina All drain into cavernous sinus -> pterygoid plexus

Question 41

What is the sensory innervation of the eye?

Answer 41

CN V1 (ophthalmic nerve) - Nasociliary - Frontal nerve - Lacrimal nerve CN V2 (maxillary nerve) - infraorbital & zygomatic

Question 42

What is present within corneal reflex?

Answer 42

CN V -> trigeminal ganglion -> close eye -> orbicularis oculi -> CN VII

Question 43

The ciliary ganglion is a ...

Answer 43

Parasympathetic ganglion

Question 44

What does the ciliary ganglion contain?

Answer 44

Cell bodies that innervates the intrinsic eye muscles

Question 45

What are the three roots of the ciliary ganglion?

Answer 45

1. Sensory - returning sensory information from the eye; CN V1 2. Sympathetic - from internal carotid plexus via ophthalmic artery or CN III; supplies the dilator pupillae 3. Motor - contains preganglionic axons from CN III to sphincter pupillae and ciliary muscles

Question 46

Postganglionic sympathetic axons....

Answer 46

1. arise from the superior cervical ganglion and travel along the cavernous plexus 2. reach the orbit on ophthalmic artery, CN III or CN V 3. traverse the ciliary ganglion without synapse 4. Innervate the dilator pupillae muscle and superior tarsal muscle

Question 47

What occurs when paralysis of dilator pupillae occurs?

Answer 47

Miosis

Question 48

What occurs when paralysis of superior tarsal muscle?

Answer 48

Mild ptosis

Question 49

What are the muscles of the eye innervated by?

Answer 49

Oculomotor nerve (CN III), trochlear nerve (IV), abducens nerve (VI)

Question 50

Key points of the oculomotor nerve in the eye

Answer 50

* arises from: cavernous sinus: * through the supraorbital fissure * divides into: parasympathetic root to ciliary ganglion

Question 51

If anisocoria occurs in the dark...

Answer 51

Sympathetics injury

Question 52

If anisocoria occurs in the light...

Answer 52

CN III injury

Question 53

What are the extraocular muscles?

Answer 53

* a common tendinous ring is derived from the orbital fascia * neurovascular structures and the common tendinous ring

Question 54

What is levator palpebrae?

Answer 54

* arises from the roof of the orbit and attaches to the upper eyelid, associated with superior tarsal muscle * Innervation: CN III

Question 55

Compressive injury of CN III?

Answer 55

PCOM aneurysm, abscess * a painful and complete oculomotor palsy that involves the pupil is most often an aneurysm * compressive injuries can affect the pupil but spare eye movements (because of the superficial location of the GVE axons in CN III)

Question 56

Ischemic injury of CN III?

Answer 56

- can spare GVE axons * a painless oculomotor palsy that spares the pupil is most often microvascular