Orbit and the Eye

Question 1

What bones make up the

• roof
• lateral wall
• medial wall
• floor of the orbit

Where is the apex and base

Answer 1

Roof
-Frontal and superior aspect of the lesser sphenoid wing

Lateral wall
-Zygomatic and lateral aspect of the lesser sphenoid wing

Medial wall
-Ethmoid, lacrimal and medial aspect of sphenoid wing

Floor
-Maxilla, zygomatic and palatine

Apex => optic canal
Base => orbital rim

Question 2

What are the 3 pathways into the orbit

Answer 2

Superior orbital fissure
Optic canal
Inferior orbital fissure

Question 3

What can be found in the superior orbital fissure

• lateral to optic canal
• middle to optic canal
• medial to optic canal

Answer 3

Lateral

• recurrent branch of opthalmic artery
• superior opthalmic vein
• lacrimal, frontal branch of V1
• IV

Middle

• VI
• superior, inferior division of III
• nasociliary branch of V1

Medial
-inferior opthalmic vein

Question 4

What can be found in the optic canal

Answer 4

• II

- opthalmic artery

Question 5

What can be found in the inferior orbital fissure

Answer 5

• infraorbital nerves and vessels

- zygomatic branch of V2

Question 6

Which 4 muscles are innervated by III

-what are their functions

Answer 6

Levator palpebrae superioris
-elevates upper eyelid

Sup rectus
-elevation, adduction, medial rotation

Medial rectus
-adduction

Inferior rectus
-depression, adduction, lateral rotation

Inferior oblique
-elevation, abduction, lateral rotation

Question 7

Which muscle is innervated by IV

• what is its function
• what is special about this muscle

Answer 7

Superior oblique
-elevation, abduction, medial rotation

Passes through the fibrocartilage trochlea

Question 8

What muscle is innervated by VI

-what is its function

Answer 8

Lateral rectus

-abduction

Question 9

Where do these muscles attach?

Answer 9

Rectus
All attach from the common tendinous ring that surrounds the optic canal
-attach to anterior sclera

Superior oblique
-sphenoid body => post aspect

Inferior oblique
-sphenoid body => medial side of orbital floor => post to lateral rectus

Superior levator palpebrae
-lesser wing above optic foramen => superior tarsal plate (SNS)

Question 10

Describe the normal pathway of vision

Answer 10

Lateral light => nasal retina
Nasal light => temporal retina

Impulses from nasal retina decussate in optic chiasm
Impulses from temporal retina do not decussate

Optic tract => LGN => optic radiations with upper and lower bank => occipital

Question 11

Describe the visual changes that occur when there is a lesion on

• optic canal
• optic chiasm
• optic tract
• single nerve in optic radiation
• macula damage
• macula sparing damage (what pathologies would cause this)

Answer 11

Optic canal => monoocular loss
Optic chiasm => bitemporal hemianopia
Optic tract => homonymous hemianopia
Single optic radiation => homonymous quadtrantopia
Macula damage => scotoma
Macula sparing => tunnel vision
-glaucoma
-retinitis pigmentosa

Question 12

Describe the route of secretions from the lacrimal gland to the nose

Describe the nervous innervation of the lacrimal nerve

Answer 12

Lacrimal gland
-exocrine gland that nourishes, cleans, lubricates eye

Lacrimal gland => excretory lacrimal ducts => superior conjunctival fornix
=> lacrimal lake => lacrimal sac => nasolacrimal duct

Lacrimal nerve (branch of V1)

• PNS => stimulates secretions
• SNS => inhibits secretions

Question 13

What is a blowout fracture

-how may it present

Answer 13

Direct trauma to orbit => maxillary fracture

-diplopia => extraocular muscle impingment => MEDICAL EMERGENCY