Orbit and Globe - Learning Objectives and Review Questions

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True/False

True/False - October 10, 2011 - Dr. Wilkinson

1. Dura provides protection for the subarachnoid space from orbital fractures.
2. Both the inferior and superior divisions of the oculomotor nerve pass through the annulus tendineus.
3. The trochlear nerve passes through the inferior orbital fissure and outside of the annulus tendineus.
4. Of the seven skeletal orbital muscles, only one takes origin from the anterior aspect of the orbit.
5. The facial arterial tree participates in an arterial anastomosis between the external and internal carotid arterial trees.
6. Posterior venous drainage of the orbit is into the cavernous sinus.
7. Infections of the eyelids run the risk of intracranial infections.
8. Pulsatile exophthalmos may reflect an arteriovenous shunt within the cavernous sinus.
9. The cavernous sinus is complex.
10. Oculomotor nerve palsy causes the resting position of the globe to be abducted.
11. Abducens nerve palsy caused the resting position of the eye to be adducted.
12. Oculomotor nerve palsy causes frank ptosis but some elevation of the superior lid is possible.
13. Emotional crying and irritant crying both involve the primary lacrimal gland but emotional crying, unlike irritant crying, does not involve the trigeminal nerve.
14. The nasolacrimal duct empties into the inferior nasal meatus.
15. The superior margin of the lacrimal sac is superior and posterior to the medial palpebral ligament.
16. A fracture of the orbital floor may cause dryness of the maxillary sinus but spare lacrimation.

True/False - October 10, 2011 - Dr. Quillen

1. The lens provides 66% of the refractive index of the globe and the cornea provides 33%.
2. The orbital septum separates the region of the face from the orbit.
3. The upper medial superior conjunctival fornix receives tears from the ducts of the lacrimal gland.
4. The eyelids play a critical role in protecting the eye.
5. The meibomian glands secrete tears in response to irritation and the lacrimal gland secretes tears to assure lubrication.
6. The meibomian glands are also known as the tarsal glands.
7. The lacrimal gland is mostly involved with reflexive tearing and the accessory lacrimal glands are primarily responsible for tear film.
8. The vascular tone of the conjunctiva, if low, leads to conjunctival injection (red eye).
9. Loss of sympathetic tone to the orbit is a cause of conjunctival injection.
10. Conjunctival injection is a symptom of Horner's syndrome.
11. Total refraction of the eye is 1/3 by cornea and 2/3 by lens.
12. Flattening the cornea changes the refractive properties of the eye.
13. The corneal arterial plexus is derived from the lacrimal artery.
14. End arteries feed the cornea and blockage of these arteries leads to corneal necrosis.
15. The pain of corneal abrasions is minor because the neural supply to the cornea is slight.
16. The primary sensory cell bodies that mediate corneal pain are located in the geniculate ganglion.
17. The primary sensory cell bodies that mediate the afferent limb of the blink reflex are located in the nodose ganglion.
18. The ciliary muscle pulls on the zonule fibers and, thus, allows the lens to thicken and provides accommodation.
19. The central retinal artery provides the arterial supply to the lens.
20. A lesion of the superior division of the oculomotor causes a failure to accommodate.
21. The vitreous makes up about 80% (4/5) of the volume of the eye.
22. The optic disc is the region of the retina having the highest visual acuity.
23. The macula of the retina is devoid of receptors and is responsible of the blind spot of the visual field.
24. The foveal avascular zone enhances the acuity of foveal vision because larger vessels are not present.
25. Approximately 1.2 million nerve fibers make up the SSA component of the optic nerve.

True/False - October 08, 2011 - Campbell/Evey

1. The ciliary body receives postganglionic fibers from the ciliary ganglion and adjusts the lens for focusing on near objects.
2. The lacrimal canaliculi drain into a common canaliculus, the lacrimal sac, then the nasolacrimal duct, to drain into the middle nasal meatus.
3. Eye drop medications may activate SVA receptors on the posterior 1/3 area of the tongue.
4. The superior tarsal plate is elevated by striate muscle with assistance from smooth muscle.
5. Frank ptosis, not mild ptosis, may reflect a lesion of the superior division of the oculomotor nerve.
6. The facial nerve mediates closing of the eyelids and the trochlear nerve mediates opening the eyelids.
7. The superior tarsal muscle is innervated by fibers having their cell bodies in the superior cervical sympathetic ganglion.
8. The greater wing of the sphenoid bone contributes borders to the superior and inferior orbital fissures.
9. The lesser wind of the sphenoid bone contributes a border to the superior orbital fissure.
10. The palatine, ethmoid, and lacrimal bones contribute to the lateral border of the orbit.
11. A blow to the face that fractures the maxilla may damage the infraorbital nerve within the orbit.
12. Passing through the annulus tendineus, but not the superior orbital fissure, is the ophthalmic artery.
13. The ophthalmic division of the trigeminal nerve elaborates nerves that pass through the annulus tendineus and nerves that pass through the superior and inferior orbital fissures but not through the annulus tendineus.
14. The four rectus muscles, but not the levator palpebrae superioris, originate from the annulus tendineus.
15. Of the six muscles that move the globe, one does not originate from the region of the apex of the orbit.
16. Rotation of the globe around the vertical axis is primarily mediated by the medial and lateral rectus muscles.
17. Intorsion of the eye is primarily mediated by the inferior oblique.
18. The axis of the orbit is 23 degrees lateral to the primary visual axis.
19. A secondary action of the superior and inferior rectus muscles is adduction.
20. The superior rectus has a tertiary action of intorsion and the inferior rectus has a tertiary action of extorsion.
21. Tilt your head while looking at your iris and in the mirror and you will notice that your globe remains "stationary."
22. The trochlear, lacrimal, and frontal nerves pass through the superior orbital fissure but not through the annulus tendineus.
23. The lateral rectus muscle has two heads of origin that create an osseofibrous foramen in conjunction with superior orbital fissure.
24. The lacrimal is conveying GVE parasympathetic and GVE sympathetic fibers to the lacrimal gland.
25. The fibers that contribute to the anterior ethmoid nerve traveled, in order, through the posterior cranial fossa, middle cranial fossa, orbit, ethmoidal air cells, anterior cranial fossa, nasal cavity, and face.
26. The fibers that contribute to the anterior ethmoid nerve traveled, in order, through the superior orbital fissure, anterior ethmoidal foramen, region of the cribriform plate, and an unnamed foramen on the bridge of the nose.
27. The arterial supply to the globe enters through the optic canal.
28. Intractable nose bleeds can be treated with orbital surgery.
29. The ophthalmic arterial distribution forms anastomoses with the facial arterial distribution within the nasal cavity and at the orbital margin.

True/False - 2010

1. Ptosis is a symptom of oculomotor nerve perturbation.
2. Mild ptosis of 2-3 mm is a symptom of oculomotor nerve perturbation.
3. The meibomian glands, more so than the lacrimal glands, are responsible for normal tearing.
4. Tearing in response to trigeminal nerve mediated irritation (reflexes) is largely by the lacrimal gland.
5. The composition of tears derived from the meibomian glands differs from that of lacrimal tears.
6. The superior conjunctival fornix uniquely receives the meibomian glands.
7. Conjunctival injection is a vasodilation of conjunctival blood vessels.
8. Cell bodies that mediate conjunctival pain are located in the geniculate ganglion.
9. Cell bodies that mediate corneal pain are located in the ciliary ganglion.
10. The corneal blink reflex involves trigeminal GSA fibers and facial GSE fibers.
11. The pupillary light reflex is mediated by SSA fibers of the optic nerve and GVE fibers of the oculomotor nerve.
12. The cornea provides two-thirds of the reflective power of the eye and the lens provide one-third.
13. The cornea is vascularized by an extension of the blood supply to the sclera.
14. An opaque cornea is disruptive to visual acuity.
15. The ciliary bodies have muscular fibers that tighten the zonule fibers and relax (thicken) the lens.
16. The ciliary bodies receive GSE fibers from the oculomotor nerve.
17. The ciliary body receive SVE fibers from the trigeminal nerve.
18. The ciliary body receives preganglionic GVE fibers from the facial nerve.
19. The motor cell bodies to the ciliary bodies are located in the ciliary ganglion.
20. Trigeminal irritation of the cornea exposed to bright light may cause you to sneeze.
21. Pituitary tumors may compress the optic tracts and cause peripheral visions defects.

True/False - 2009

1. Mueller's muscle (superior tarsal muscle) assists the tendon of levator palpebrae superioris to raise the superior tarsal plate.
2. The conjunctiva provide a fascial boundary between the face and the orbit.
3. The lacrimal gland secretes tears into the superior medial conjunctival fornix.
4. The extraocular muscles are seven in number.
5. The trochlear nerve is so named for the trochlea of the inferior oblique muscle.
6. The superior oblique muscle moves the globe in abduction, depression, and medial rotation.
7. The lateral rectus muscle adducts the globe and is the sole innervation of the abducens nerve.
8. The inferior oblique muscle elevates, abducts, and laterally rotates the globe.
9. The lateral wall of the orbit
10. Between the lateral wall and the inferior wall of the orbit is the superior orbital fissure.
11. The frontal bone and the greater wing of the sphenoid contribute to the superior wall of the orbit.
12. The maxilla and the temporal process of the temporal bone contribute to the inferior wall of the orbit.
13. The zygomatic bone and the lesser wing of the sphenoid contribute to the lateral wall of the orbit.
14. The optic canal is through the lesser wing of the sphenoid bone.
15. The foramen ovale, foramen rotundum, and foramen spinosum are foramina of the greater wing of the sphenoid bone.
16. The perpendicular plate of the palatine bone contributes to the medial wall of the orbit.
17. The annulus tendineus provides a site of origin for the rectus muscle of the orbit but not the for the superior oblique.
18. The nasociliary nerve, but not the frontal or trochlear nerves, pass through the annulus tendineus.
19. The ophthalmic artery enters the orbit from the middle cranial fossa by way of the optic canal.
20. The superior division of the oculomotor nerve conveys GVE and GSE fibers into the orbit.
21. The superior oblique and the superior tarsal muscle are both innervated by the superior division of the oculomotor nerve.
22. The abducens nerve travels distally from the cavernous sinus, through the superior orbital fissure, passing within the annulus tendineus, and then enters the medial surface of the lateral rectus within the orbit.
23. The posterior ethmoidal nerve, a branch of the trochlear nerve, enters the regions of the posterior ethmoidal air cells and the sphenoid sinus.
24. The long ciliary nerves pass through the ciliary ganglion and the short ciliary.
25. Most distally, the anterior ethmoidal nerve supples sensation to the bridge of the nose as the external nasal nerve.
26. Fibers within the external nasal nerve traveled, in order, through the posterior cranial fossa, middle cranial fossa (cavernous sinus), orbit, anterior ethmoidal sinus, anterior cranial fossa, nasal cavity, and face.
27. The ciliary ganglion is the site of postganglionic sympathetic cell bodies that mediate pupil constriction.
28. The superior and inferior oblique muscles are known as torsional muscles.
29. Pituitary tumors compress the medial fibers of the optic nerves resulting in temporal field deficits.
30. The posterior chamber occupies about 4/5ths the volume of the globe whereas the anterior chamber occupies about 1/5th.
31. The iris separates the anterior chamber from the posterior chamber.
32. Corneal nutrient supply is by way of the microvasculature.
33. The cornea provides 1/3 of the total refractive index for the globe and the lens provides 2/3 of the refractive index.
34. The lacrimal gland releases tears into the inferior conjunctival fornix.
35. The lacrimal gland is reflexive to trigeminal nerve mediated irritation whereas the accessory lacrimal glands provide continuous lubrication to the globe.
36. The cell bodies that mediate corneal pain are located in the trigeminal ganglion.
37. The cell bodies that mediate the afferent limb of the corneal blink reflex are located in the trigeminal motor nucleus.
38. A lesion of the cervical sympathetic trunk is expected to cause conjunctival injection (dilation of the vessels within the conjunctiva).
39. A lesion of the inferior division of the oculomotor nerve is apt to interfere with accommodation (focusing on near objects).
40. A lesion of the superior division of the oculomotor nerve is expected to leave the globe in a depressed position.
41. An adducted eye paired with an impressive infection of the upper lip is a grave symptom.
42. Pulsatile exophthalmus is associated with a denervation of the lacrimal gland.
43. The site of the preganglionic cell bodies that mediate accommodation is the Edinger-Westphal nucleus.
44. The site of the postganglionic cell bodies that mediate accommodation is the otic ganglion.
45. A lesion of the facial nerve at the internal acoustic meatus (e.g. acoustic neuroma) may cause tearing deficiencies.
46. A lesion of the facial nerve at the stylomastoid foramen may cause corneal erosion.
47. The ciliary ganglion is a sympathetic ganglion. Nevertheless, parasympathetic fibers pass through the ganglion without synapsing.
48. The short ciliary nerves are, strangely enough, longer than the long ciliary nerves.
49. The frontal nerve, lacrimal nerve, and trochlear nerve all enter the orbit without passing through the annulus tendineus.
50. The superior and inferior ophthalmic arteries combine near the apex of the orbit to form the anterior extension of the cavernous sinus.
51. The superior orbital fissure has the greater wing of the sphenoid bone as a superior boundary and the lesser wing of the sphenoid as an inferior boundary.
52. A lesion of the internal carotid nerve is expected to cause unilateral chronic constriction of the pupil.
53. A tumor at the apex of the lung is expected to cause unilateral pupil constriction.
54. A cavernous sinus infection is expected to cause unilateral pupil constriction given that the inferior division of the oculomotor nerve remains healthy.
55. A mild ptosis in a young person is apt to be caused by an autonomic disturbance whereas a frank ptosis is caused by a somatic disturbance.
56. Sneezing while looking at bright light is thought to be, in part, mediated by the trigeminal nerve and not the optic nerve.
57. The anterior ethmoidal nerve leaves the orbit to enter the anterior cranial fossa after having passed through the sphenoid sinus.
58. The anterior ethmoidal artery can be ligated in the orbit to stop epistaxis (severe nose bleed).
59. The anterior ethmoidal nerve provides sensation along the bridge of the nose.
60. The short ciliary nerves host postganglionic parasympathetic fibers and preganglionic sympathetic fibers.
61. The motor root (parasympathetic root) of the ciliary ganglion is derived from the superior division of the oculomotor nerve.
62. The infraorbital nerve, while in the infraorbital canal, carries postganglionic parasympathetic fibers destined for the lacrimal gland.
63. The zygomaticotemporal nerve leaves the orbit superior the the exit of the zygomaticofacial nerve.
64. A lesion of the greater superficial petrosal nerve is expected to cause unilateral disruption of tearing.
65. A lesion of the lesser superficial petrosal nerve is expected to cause a mild ptosis.

Essay

1. Discuss the anatomy of the orbit. Include relationships, fascial specializations, vascularization, innervation, lymphatics, muscles and movements, and nerve injury.
2. Discuss the anatomy of the annulus tendineus. Include relationships.
3. Discuss the autonomic innervation to the orbit and globe. Include preganglionic and postganglionic pathways leading to the orbit.

Short Answer

1. Discuss the venous communications between the face and the cavernous sinus.
2. Discuss the fascial barriers that separate the face from the orbit.
3. Discuss elevation of the superior tarsal plate. Include somatic and autonomic innervations.
4. Discuss the oblique muscles and their contribution to stabilizing the visual field.
5. Describe the path of a tear beginning with the lacrimal gland and ending at the inferior nasal meatus.
6. Discuss the elevation of the superior tarsal plate
7. Discuss the elaboration and circulation of fluid within the globe.
8. Discuss the glandular secretions that wet the cornea.
9. Discuss Horner's syndrome and its effect on the functions of the orbit.

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