Anatomy

Front 1

1. What are the four bony walls of the orbit?

Back 1

1. Medial

2. Lateral

3. Superior

4. Inferior

Front 2

2. What is the orbital axis?

Why is it important?

Back 2

Line drawns from the center of the optic canal to the center of the orbital margin

Optic nerve course approximates this axis

Also, two extra ocular muscles (superior and inferior rectus) follow this axis

Front 3

3. What forms the superior wall or roof of the orbit?

Back 3

1. Orbital part of frontal bone

2. Lesser wing of sphenoid bone
*forms the posterior part of the orbital roof

Front 4

4. What lies in the supraorbital notch or foramen?

Back 4

Transmits supraorbital nerve and vessels into forehead

**can be used as a point to locally anesthetize the forehead and anterior scalp

Front 5

5. What is the trochlea?

Back 5

Ring-line fibrocartilaginous pulley through which the tendon of the superior oblique muscle passes

Front 6

6. What are the important superior extraorbital relationships of the orbital roof?

Back 6

1. To the anterior cranial fossa and its contained frontal lobes of the brain

2. Portion of the frontal paranasal air sinus

Front 7

7. What are the bones that make up the medial orbital wall?

Back 7

1. Orbital part of frontal bone (uppermost part)

2. Orbital face of maxilla (lowermost part)

3. Frontal process of maxilla (medial orbital margin)

4. Lacrimal bone (separate orbit from nasal cavity)

5. Ethmoid bone (forms largest part of medial wall)

6. Body of sphenoid (most posterior part of medial wall)

Front 8

8. What disease can invade the orbit through the medial wall?

Back 8

Disease of the....

1. Sphenoid sinus

2. Ethmoid air cells

3. Nasal cavity

Front 9

9. What forms the inferior wall of the orbit?

What is the major inferior relation of the orbit?

Back 9

1. Maxilla (medially)

2. Zygomatic bone (laterally)

Maxillary paranasal air sinus

Front 10

10. What forms the lateral wall of the orbit?

What is the anterior part of the lateral wall related to?

What is the posterior part of the lateral wall related to?

Back 10

1. Zygomatic bone (anteriorly)

2. Greater wing of the sphenoid (posteriorly)

Temporal fossa and face

Lateral part of middle cranial fossa

Front 11

11. What does the inferior orbital fissure transmit?

Back 11

1. Zygomatic nerves

2. Infraorbital nerve and vessels

3. Some venous communications bwt opthalmic veins and pterygoid venus plexus

Front 12

12. What does the superior orbital fissure transmit?

Back 12

1. Oculomotor nerve

2. Trochlear nerve

3. Abducens

4. Opthalmic division of trigeminal

Front 13

13. Where do the six voluntary orbital muscles originate?

Back 13

From or near the common ring tendon

**encircles both the optic canal and the medial part of the superior orbital fissure

Front 14

14. What forms each eyelid?

Back 14

(anterior to posterior)

1. Skin

2. Palpebral portion of orbicularis oculi muscle

3. Tarsus

4. Conjunctiva

Front 15

15. What does the lacrimal duct open into?

Where do the constant tears produced stream across?

Back 15

Open into the lateral part of the superior conjunctival fornix

1. Across the bulbar surface (movement facilitated by blinking)

2. Along lid margins to inner canthus (where upper/lower eyelids meet)

3. Superior and inferior lacrimal canaliculi drain medially into the larcrimal sac

4. Descend into inferior meatus of nose via nasolacrimal duct

Front 16

16. Where is the levator palpebrae superioris muscle?

Origin?

Insertion?

IN?

Function?

Back 16

Most superiorly situated muscles in orbit

O: common ring tendon region

I: tarsus and dermis of upper eyelid

IN: superior division of oculomotor nerve

F: voluntary elevator of upper eyelid

Front 17

17. What is the origin of the superior tarsal muscles?

Insertion?

Innervation?

Function?

Back 17

O: inferior aspect of fascial covering about levator palpebrae superioris

I: Upper border of superior tarsus

IN: sympathetic nerve fibers

F: involuntary elevator of the eyelid

Front 18

18. What are the four muscles of attached to the anterior portion of the eyeball?

From where do they all arise?

Back 18

Rectus muscles
-lateral, medial, superior and inferior

Common ring tendon

Front 19

19. Where does the lateral rectus insert?

Innervation?

Function?

Back 19

I: Lateral aspect of anterior part of eyeball

IN: abducens nerve
**only muscle innervated by CN IV

F: primary adbuctor of eyeballs

Front 20

20. What is the insertion, innervation and function of the medial rectus muscle?

Back 20

I: Medial aspect of anterior portion of eyeball

IN: inferior division of oculomotor nerve

F: primary adductor of the eyeball

Front 21

21. What is the insertion, innervation and function of the superior rectus muscles?

Back 21

I: superior aspect of anterior part of eyeball

IN: superior division of oculomotor nerve

Function:
1. Elevator
2. Adductor about vertical axis
3. Intorter about anteroposterior axis

Front 22

22. What is the insertion, innervation and function of the inferior rectus muscle?

Back 22

I: inferior aspect of anterior part of eyeball

IN: inferior division of oculomotor nerve

Function:
1. Depresses eyeball
2. Adduction
3. Extortion

Front 23

23. What is the origin, insertion, innervation and function of the superior oblique muscle?

Back 23

O: region of common ring tendon

I: superior aspect of posterior part of eyeball

IN: trochlear nerve

Function:
1. Depression of corneal pole of eye
2. Abduct corneal pole
3. Intortion

Front 24

24. What is the origin, insertion, innervation and function of the inferior oblique muscle?

Back 24

O: Medial part of inferior orbital wall

I: Inferolateral aspect of posterior part of bulb

IN: inferior division of oculomotor nerve

Function:
1. Elevates the cornea
2. Abduction of corneal pole of eye
2. Extorsion

Front 25

25. What happens when the ciliary muscles contract?

Back 25

1. Choroid is pulled forward into ciliary body

2. Narrow inner diameter of ciliary body

3. Lens rounds up

**accommodation

Front 26

26. What is the sphincter pupillae muscle?

Back 26

Smooth muscle arranged circulary about the inner margin of the pupil

Contraction causes narrowing of the pupil

Under control of parasympathetic fibers from the oculomotor nerve

Front 27

27. What is the dilator pupillae muscle under the control of?

Back 27

Sympathetic control

Front 28

28. What does testing the extraocular muscles provide a means of evaluating?

Back 28

Three cranial nerves

Midbrain and pons level of brain

Front 29

29. How do you test the lateral and medial rectus muscles?

How can you test both the superior rectus and inferior oblique?

How can you test both the inferior rectus and superior oblique?

Back 29

Ask patient to follow finger laterally and medially

Ask patient to follow finger superiorly into elevation

Ask patient to follow finger inferiorly into depression

Front 30

30. How can the inferior oblique be isolated and tested?

How can the superior oblique be isolated and tested?

Back 30

First adduct the eye and then elevate it

**adduction pust superior rectus at mechanical disadvantage

First adduct the eye then depress it

**adduction puts inferior rectus at disadvantage

**primary test for trochlear nerve integrity

Front 31

31. How can the superior rectus be isolated and tested?

How can the inferior rectus be isolated and tested?

Back 31

Eye is first abducted and then elevated

**adbuction puts inferior oblique at mechanical disadvantage

First adbuct the eye and then depress it

**put superior oblique at mechanical disadvantage

Front 32

32. Where does the oculomotor nerve divide?

Where does the opthalmic division of the trigeminal nerve divide?

Back 32

In the cavernous sinus (lateral wall) into a superior and inferior division

Lateral wall of cavernous sinus into frontal, lacrimal, and nasociliary nerve

**opthalmic division of V is entirely sensory

Front 33

33. What nerves in the most superior plane of the orbit (bwt periorbita and most superior orbital muscles?

Back 33

1. Trochlear nerve
-superior oblique muscle

2. Frontal branch of opthalmic V
-superior aspect of levator palpebrae superioris
-gives off supraorbital branch
**sensory innervation of forehead and anterior scalp

3. Lacrimal branch of opthalmic V
**sensory innervation to lacrimal gland and lateral eyelid

Front 34

34. What structures are in the second plane of the orbit bwt the superior rectus and optic nerve?

Back 34

1. Superior division of the oculomotor nerve
**innervate levator palpebrae superioris

2. Nasociliary branch of opthalmic V
-across superior aspect of optic nerve
**accompanied by opthalmic artery
**both give off an ethmoidal branch

3. Superior opthalmic vein

Front 35

35. What is the third plane of the orbit bwt the optic nerve and lateral rectus muscle?

Back 35

1. Abducens nerves
-medial aspect of lateral rectus

2. Ciliary parasympathetic ganglion

**along w/ its sensory and motor roots and short ciliary nerves

Front 36

36. What is in the fourth plane of the orbit bwt the optic nerve and the inferior rectus muscle?

Back 36

1. Inferior division of oculomotor nerve
-border of inferior rectus

2. Inferior opthalmic vein

Front 37

37. What does the optic nerve contain?

Where does the optic nerve end?

Back 37

SSA nerve fibers for vision

At the optic chiasm BUT the nerve fibers in optic nerve continue through chiasm and form optic tract

Front 38

38. What accompanies the optic nerve at it enters the cranial cavity through the optic canal?

What arises from the opthalmic artery in the posterior orbit?

Back 38

Ophthalmic artery (inferior to nerve)

Central artery of the retina

Front 39

39. What does the oculomotor nerve contain?

As it emerges from the midbrain what accompanies it?

Back 39

(G)SE fibers to the levator palpebrae superioris, superior rectus, medial rectus, inferior rectus and inferior oblique muscle

GVE parasympathetic preganglionic fibers to the ciliary ganglion

**post ganglionic fibers will distribute to the sphinctor pupillae and ciliary muscles of bulb

Upper basilar artery (medial)
Superior cerebellary artery (inferior)
Posterio cerebral artery (superior)

Front 40

40. What does the ciliary ganglion receive?

What are the short ciliary nerves?

Back 40

1. Parasympathetic pre-ganglionic nerve fibers from motor root

2. Sensory root which comes of nasociliary nerve

Mixed nerves conveying sensory, sympathetic postganglionic and parasympathetic postganglionic fibers

Front 41

41. If the oculomotor nerve is injured, what will happen?

Back 41

1. Ptosis (loss of levatory palpebrae)

2. External strabismus (eye in fixed abducted position)

3. Double vision (horizontal diplopia)

4. Near vision impaired

5. Dilated pupil

Front 42

42. What provides a good test for the integrity of the optic and oculomotor nerves?

Back 42

Pupillary light reflex b/c they are its respective sensory and motor limbs

No pupillary response in either but normal bilateral response --> sensory limb defect

No pupillary response in one eye but other does --> motor limb defect

Front 43

43. What does the trochlear nerve contain?

What's special about its origin?

Back 43

(G)SE fibers to superior oblique muscles

Only CN to emerge from dorsal aspect of brainstem

Only CN whose root fibers cross completely before exiting brain

Front 44

44. What happens if the trochlear nerve is injured?

How is the nerve tested?

Back 44

Vertical diplopia (double vision)

First adducting and then attempting to depress the eye

Front 45

45. What does the abduncens nerve contain?

How is its course?

Back 45

(G)SE fibers to the lateral rectus muslce

Has longest intracranial and intradural course of any CN

**high hazard course w/ close arterial, hypophysial, sphenoid sinuse and cavernous sinuse relationship

Front 46

46. What happens if CN VI is injured?

Back 46

Internal strabismus (adducted eye that can still be moved vertically)

Complain of horizontal diplopia

Front 47

47. What does the ophthalmic division V contain?

Back 47

GSA fibers whose nerve cell bodies are in the trigeminal ganglion

**ganglion has intimate inferior relation w/ internal carotid artery

Front 48

48. What does the nasociliary nerve give off?

Back 48

Long ciliary branches to the eyebal and indirect branches that enter short ciliary nerves

**important sensory innervation to cornea and scelra and afferent limb of corneal reflex

Front 49

49. What is a good test for the integrity of the trigeminal and facial nerves?

Back 49

Corneal blink reflex since they provide sensory and motor limbs respectively

No blink response in either eye but normal bilateral blink response --> sensory defect

No blink response in one eye but in the other --> motor defect

Front 50

50. What are some other important branches of the nasociliary nerve?

What does this innervate?

Back 50

Ethmoidal branches

1. Ethmoid air cells

2.Dura of anterior cranial fossa
3. Upper nasal cavity

4. Dorsum of external nose

Front 51

51. Where does the sympathetic preganglionic innervation to the orbit originate?

What do they enter when they exit the spinal cord?

What do they do here?

Back 51

T1 or T2 spinal cord levels

Enter stellate ganglion levels of sympathetic trunk

Synapse on postganglionic sympathetic neurons

Front 52

52. What do they supply in the orbit?

What happens if this pathway is interrupted anywhere on its course?

Back 52

Superior tarsal muscle and dilator pupillae muscle

Fixed constricted pupil (miosis) and ptosis (caused by loss of superior tarsal)

Also have sweating over forehead and flushing/blushing of forehead

Front 53

53. Where does the ophthalmic artery arise from?

How does it enter the orbit?

What are its major branches?

Back 53

Internal carotid artery as soon as it emerges from the cavernous sinus

Through the optic canal inferior to the optic nerve

1. Central artery of retina

2. Posterior ciliary branches

Front 54

54. What do these branches supply?

Back 54

1. Vascular tunic of the eye

2. Lacrimal branch to the gland

3. Supraorbital branch to the forehead and anterior scalp

4. Ethmoidal branches

Front 55

55. How does the ophthalmic vein receive venous drainage from the eye?

Back 55

Through both the central retinal veins (drain much of the retina)

AND

Four vorticose veins (drain vascular tunic)

Front 56

56. What does the ophthalmic vein communicate with?

Which ophthalmic vein is larger?

Back 56

1. Branches of facial vein (anteriorly)

2. Pterygoid venous plexus

3. Cavernous sinus

Superior

**both are situated above and below the optic nerve