Orbit in Human Anatomy MCQ Questions and Answers

1. The roof of the orbit is formed mainly by the:
A) Zygomatic bone
B) Frontal bone (orbital plate)
C) Maxilla (orbital surface)
D) Lacrimal bone
Answer: B) Frontal bone (orbital plate)

2. The inferior orbital fissure transmits which major structure?
A) Optic nerve (CN II)
B) Infraorbital nerve (branch of V2) and zygomatic nerve
C) Superior ophthalmic vein only
D) Trochlear nerve (CN IV)
Answer: B) Infraorbital nerve (branch of V2) and zygomatic nerve

3. The medial wall of the orbit contains which thin bone that is often the first involved in blowout fractures?
A) Frontal bone
B) Maxilla (orbital surface)
C) Lacrimal bone
D) Zygomatic bone
Answer: C) Lacrimal bone

4. The optic canal is located in which orbital boundary?
A) Inferior wall
B) Lateral wall
C) Roof (sphenoid part) near apex
D) Floor close to infraorbital foramen
Answer: C) Roof (sphenoid part) near apex

5. The structure that separates the orbital cavity from the middle cranial fossa at the apex is the:
A) Superior orbital fissure
B) Inferior orbital fissure
C) Supraorbital notch
D) Optic canal
Answer: D) Optic canal

6. The muscle that elevates and abducts the eyeball (primary elevator in primary gaze) is the:
A) Lateral rectus
B) Medial rectus
C) Superior rectus
D) Inferior oblique
Answer: C) Superior rectus

7. Which extraocular muscle is innervated by the abducent nerve (CN VI)?
A) Superior oblique
B) Lateral rectus
C) Medial rectus
D) Superior rectus
Answer: B) Lateral rectus

8. The trochlea functions as a pulley for which muscle?
A) Superior rectus
B) Superior oblique
C) Inferior oblique
D) Inferior rectus
Answer: B) Superior oblique

9. The inferior oblique muscle originates from:
A) Annulus of Zinn at apex
B) Maxillary bone at the anterior floor near lacrimal fossa (medial orbital floor)
C) Lateral orbital wall
D) Orbital surface of zygoma
Answer: B) Maxillary bone at the anterior floor near lacrimal fossa (medial orbital floor)

10. The common tendinous ring (annulus of Zinn) gives origin to all of the following EXCEPT:
A) Medial rectus
B) Lateral rectus
C) Superior rectus
D) Inferior oblique
Answer: D) Inferior oblique

11. The superior ophthalmic vein drains into the:
A) External jugular vein directly
B) Cavernous sinus
C) Pterygoid venous plexus only
D) Facial vein only
Answer: B) Cavernous sinus

12. Which nerve carries parasympathetic fibers to the lacrimal gland via a relay in the pterygopalatine ganglion?
A) Direct lacrimal branch of V1
B) Greater petrosal nerve → nerve of pterygoid canal pathway (via CN VII parasympathetics)
C) Oculomotor (CN III)
D) Optic nerve (CN II)
Answer: B) Greater petrosal nerve → nerve of pterygoid canal pathway (via CN VII parasympathetics)

13. The sensory innervation of the cornea is mainly from which nerve?
A) Lacrimal branch of facial nerve
B) Long ciliary nerves (from nasociliary branch of V1)
C) Infraorbital nerve (V2)
D) Recurrent laryngeal nerve
Answer: B) Long ciliary nerves (from nasociliary branch of V1)

14. The oculomotor nerve (CN III) provides parasympathetic fibers to the:
A) Lacrimal gland via direct branch in orbit
B) Sphincter pupillae and ciliary muscle (via short ciliary nerves after ciliary ganglion)
C) Levator palpebrae superioris only
D) Lateral rectus muscle
Answer: B) Sphincter pupillae and ciliary muscle (via short ciliary nerves after ciliary ganglion)

15. The tendon of which muscle passes over the superior margin of the globe to insert on the sclera posteriorly and produce intorsion?
A) Superior rectus
B) Superior oblique (via trochlea)
C) Inferior oblique
D) Lateral rectus
Answer: B) Superior oblique (via trochlea)

16. The lacrimal sac lies in the lacrimal groove formed by lacrimal bone and:
A) Frontal process of zygoma
B) Frontal process of maxilla
C) Nasal bone
D) Ethmoid bone
Answer: B) Frontal process of maxilla

17. The orbital septum is a continuation of which fascial layer?
A) Periorbita (periosteum of orbit)
B) Orbital extension of the superficial musculoaponeurotic system (continuation of periorbita to eyelids; often described as extension of orbital periosteum / periorbita)
C) Dura mater only
D) Conjunctiva only
Answer: B) Orbital extension of the superficial musculoaponeurotic system (continuation of periorbita to eyelids; often described as extension of orbital periosteum / periorbita)

18. The structure forming the medial canthus contains the lacrimal sac and is stabilized by which ligament?
A) Lateral palpebral ligament only
B) Medial palpebral ligament (tarsal plate attachments)
C) Zygomatic ligament
D) Suspensory ligament of Lockwood
Answer: B) Medial palpebral ligament (tarsal plate attachments)

19. The orbital apex contains all of the following structures EXCEPT:
A) Optic canal contents
B) Superior orbital fissure contents
C) Infraorbital foramen
D) Common tendinous ring attachment
Answer: C) Infraorbital foramen

20. The nerve supplying motor fibers to levator palpebrae superioris is:
A) Trochlear nerve (CN IV)
B) Abducent nerve (CN VI)
C) Oculomotor nerve (CN III) — superior division
D) Facial nerve (CN VII)
Answer: C) Oculomotor nerve (CN III) — superior division

21. The eyelid muscle responsible for fine control of eyelid closure (orbital part) is the:
A) Levator palpebrae superioris
B) Orbicularis oculi (orbital portion)
C) Superior tarsal (Müller’s) muscle
D) Frontalis muscle
Answer: B) Orbicularis oculi (orbital portion)

22. The sympathetic innervation to the superior tarsal (Müller’s) muscle originates from which ganglion?
A) Pterygopalatine ganglion
B) Superior cervical ganglion
C) Submandibular ganglion
D) Ciliary ganglion
Answer: B) Superior cervical ganglion

23. A lesion of the superior orbital fissure can produce all of the following EXCEPT:
A) Ophthalmoplegia involving CN III, IV, VI
B) Loss of corneal reflex afferent (V1)
C) Loss of infraorbital sensation (V2)
D) Ptosis due to levator palpebrae dysfunction
Answer: C) Loss of infraorbital sensation (V2)

24. The orbit communicates posteriorly with the middle cranial fossa through the:
A) Foramen rotundum only
B) Superior orbital fissure and optic canal
C) Infraorbital foramen
D) Inferior orbital fissure only
Answer: B) Superior orbital fissure and optic canal

25. The primary blood supply to the orbit is from the:
A) Facial artery
B) External carotid artery branches solely
C) Ophthalmic artery (branch of internal carotid artery)
D) Maxillary artery only
Answer: C) Ophthalmic artery (branch of internal carotid artery)

26. The central retinal artery is a branch of the:
A) Superior ophthalmic vein
B) Ophthalmic artery (branch of internal carotid)
C) External carotid artery
D) Internal maxillary artery
Answer: B) Ophthalmic artery (branch of internal carotid)

27. The long ciliary nerves carry which fibers?
A) Parasympathetic only
B) Sensory (from cornea) and sympathetic (for dilator pupillae)
C) Motor to EOMs
D) Taste fibers to palate
Answer: B) Sensory (from cornea) and sympathetic (for dilator pupillae)

28. The short ciliary nerves arise from which ganglion?
A) Pterygopalatine ganglion
B) Superior cervical ganglion
C) Ciliary ganglion (postganglionic parasympathetic to sphincter pupillae & ciliary muscle)
D) Otic ganglion
Answer: C) Ciliary ganglion (postganglionic parasympathetic to sphincter pupillae & ciliary muscle)

29. The inferior orbital fissure communicates with the:
A) Middle cranial fossa only
B) Pterygopalatine fossa and infratemporal fossa
C) Nasal cavity directly
D) Anterior cranial fossa
Answer: B) Pterygopalatine fossa and infratemporal fossa

30. The orbital septum helps to limit the spread of infection from the eyelid to the:
A) Sphenoid sinus
B) Orbit (posterior orbital cellulitis is limited)
C) Cavernous sinus directly
D) Maxillary sinus
Answer: B) Orbit (posterior orbital cellulitis is limited)

31. The tendon of insertion of the superior oblique inserts on the:
A) Lateral sclera posteriorly
B) Posterior-superior-lateral aspect of sclera after passing through trochlea
C) Inferior medial sclera
D) Medial canthus periosteum
Answer: B) Posterior-superior-lateral aspect of sclera after passing through trochlea

32. The ophthalmic division of trigeminal nerve (V1) provides sensory supply to all the following EXCEPT:
A) Cornea
B) Upper eyelid skin
C) Upper teeth and gingiva
D) Lateral nose skin near root
Answer: C) Upper teeth and gingiva

33. The orbital rim anteriorly includes the zygomatic, frontal, and:
A) Palatine bone only
B) Maxilla (frontal process)
C) Sphenoid wing
D) Ethmoid labryinth
Answer: B) Maxilla (frontal process)

34. The muscle that elevates the lower eyelid (and is sympathetically innervated) is:
A) Levator palpebrae superioris
B) Orbicularis oculi
C) Inferior tarsal muscle (part of inferior rectus complex / Müller’s homologue — contributes to lower lid position)
D) Frontalis muscle
Answer: C) Inferior tarsal muscle (part of inferior rectus complex / Müller’s homologue — contributes to lower lid position)

35. The lacrimal gland’s excretory ducts open into the:
A) Conjunctival sac in the lateral upper fornix
B) Medial canthus only
C) Conjunctival sac in the superior fornix (lateral part)
D) Inferior fornix only
Answer: C) Conjunctival sac in the superior fornix (lateral part)

36. The orbital fat is important clinically because it:
A) Prevents eye movement
B) Cushions globe and allows free movement of extraocular muscles; loss leads to enophthalmos
C) Is the site of tear production
D) Contains only white blood cells
Answer: B) Cushions globe and allows free movement of extraocular muscles; loss leads to enophthalmos

37. The eyelid’s tarsal plate contains glands that produce the lipid layer of tear film named:
A) Meibomian glands (tarsal glands)
B) Meibomian glands (tarsal glands)
C) Goblet cells of conjunctiva
D) Lacrimal gland only
Answer: B) Meibomian glands (tarsal glands)

38. The mucous membrane covering the posterior surface of the eyelids and anterior eyeball is called:
A) Sclera
B) Cornea
C) Conjunctiva
D) Tarsal plate
Answer: C) Conjunctiva

39. The optic nerve sheath is a continuation of which cranial meningeal layer?
A) Pia mater only
B) Dura, arachnoid, and pia mater (meninges continue around optic nerve; subarachnoid space contains CSF)
C) Periosteum only
D) Periorbita only
Answer: B) Dura, arachnoid, and pia mater (meninges continue around optic nerve; subarachnoid space contains CSF)

40. Compression of the optic nerve in the optic canal first leads to loss of:
A) Peripheral visual field only
B) Pupillary light reflex (afferent limb) and then visual acuity
C) Extraocular movements
D) Lacrimation
Answer: B) Pupillary light reflex (afferent limb) and then visual acuity

41. The superior tarsal (Müller’s) muscle receives sympathetic innervation and contributes to:
A) Forced eyelid closure
B) Elevation of upper eyelid (tonic support)
C) Brow elevation
D) Corneal reflex
Answer: B) Elevation of upper eyelid (tonic support)

42. The ciliary ganglion lies in the orbit between which two structures?
A) Lateral rectus and zygoma
B) Lateral rectus and optic nerve near the muscle cone (close to the posterior globe)
C) Levator and superior rectus only
D) Inferior oblique and maxilla
Answer: B) Lateral rectus and optic nerve near the muscle cone (close to the posterior globe)

43. The blink (corneal) reflex afferent limb is mediated by:
A) Facial nerve (CN VII) sensory fibers
B) Ophthalmic division of trigeminal (V1) — long ciliary/ophthalmic branches
C) Oculomotor nerve (CN III)
D) Hypoglossal nerve (CN XII)
Answer: B) Ophthalmic division of trigeminal (V1) — long ciliary/ophthalmic branches

44. The efferent limb of the corneal blink reflex is carried by:
A) Trigeminal motor branches
B) Facial nerve (temporal & zygomatic branches to orbicularis oculi)
C) Oculomotor nerve (CN III)
D) Glossopharyngeal nerve (CN IX)
Answer: B) Facial nerve (temporal & zygomatic branches to orbicularis oculi)

45. The orbital floor is mainly formed by the:
A) Zygomatic bone only
B) Maxilla (orbital plate) and zygomatic bone, with contribution from palatine bone
C) Frontal process of zygoma only
D) Sphenoid greater wing
Answer: B) Maxilla (orbital plate) and zygomatic bone, with contribution from palatine bone

46. An inferior orbital (blowout) fracture commonly traps which muscle causing diplopia on upward gaze?
A) Lateral rectus
B) Medial rectus
C) Inferior rectus or inferior oblique (inferior rectus most commonly)
D) Superior oblique
Answer: C) Inferior rectus or inferior oblique (inferior rectus most commonly)

47. The eyelid retractor in the upper lid is the:
A) Orbicularis oculi
B) Levator palpebrae superioris
C) Superior tarsal muscle only
D) Frontalis directly
Answer: B) Levator palpebrae superioris

48. The ophthalmic artery enters the orbit via the:
A) Inferior orbital fissure
B) Optic canal (inferolateral to optic nerve in most cases)
C) Supraorbital notch only
D) Superior orbital fissure exclusively
Answer: B) Optic canal (inferolateral to optic nerve in most cases)

49. The supraorbital foramen/notch transmits the supraorbital nerve which is a branch of:
A) Maxillary nerve (V2)
B) Mandibular nerve (V3)
C) Ophthalmic nerve (V1) — frontal branch (supraorbital nerve)
D) Facial nerve (CN VII)
Answer: C) Ophthalmic nerve (V1) — frontal branch (supraorbital nerve)

50. The levator palpebrae superioris is innervated by which branch of CN III?
A) Inferior division only
B) Superior division (oculomotor nerve)
C) Trochlear nerve
D) Facial nerve
Answer: B) Superior division (oculomotor nerve)

51. The lateral wall of the orbit contains which bone contribution?
A) Lacrimal bone
B) Zygomatic bone and greater wing of sphenoid
C) Maxillary orbital surface only
D) Ethmoid lamina papyracea
Answer: B) Zygomatic bone and greater wing of sphenoid

52. The orbital septum attaches to which structure in the eyelids?
A) Orbicularis oculi only
B) Tarsal plates
C) Conjunctiva only
D) Levator aponeurosis only
Answer: B) Tarsal plates

53. The primary blood supply to the eyelids (medial and lateral palpebral arteries) are branches of which artery?
A) Facial artery exclusively
B) Ophthalmic artery (via medial and lateral palpebral branches from dorsal nasal and lacrimal arteries and facial via angular)
C) Maxillary artery only
D) External carotid directly to upper eyelid
Answer: B) Ophthalmic artery (via medial and lateral palpebral branches from dorsal nasal and lacrimal arteries and facial via angular)

54. The sensory innervation to the upper eyelid skin is mainly from which branch?
A) Infraorbital nerve (V2)
B) Supraorbital nerve (branch of V1)
C) Buccal branch of facial nerve
D) Mandibular nerve (V3)
Answer: B) Supraorbital nerve (branch of V1)

55. The orbital part of the lacrimal apparatus that collects tears drains into the:
A) Sphenoid sinus directly
B) Lacrimal sac via lacrimal canaliculi at medial canthus
C) Inferior meatus of nose directly
D) Superior meatus only
Answer: B) Lacrimal sac via lacrimal canaliculi at medial canthus

56. The ciliary muscles effect accommodation by changing the shape of the:
A) Cornea only
B) Lens (via zonular fiber tension changes)
C) Sclera curvature
D) Eyeball axial length only
Answer: B) Lens (via zonular fiber tension changes)

57. The orbital roof near the frontal sinus can be thin and is formed partly by the:
A) Maxillary bone only
B) Orbital plate of frontal bone (and small contribution of lesser wing of sphenoid posteriorly)
C) Zygomatic bone only
D) Ethmoid bone only
Answer: B) Orbital plate of frontal bone (and small contribution of lesser wing of sphenoid posteriorly)

58. The fascial sheath surrounding the eyeball, continuous with the dura at the optic canal, is called:
A) Periosteum only
B) Tenon’s capsule (bulbar fascia)
C) Conjunctiva only
D) Orbital septum exclusively
Answer: B) Tenon’s capsule (bulbar fascia)

59. The inferior ophthalmic vein drains primarily into:
A) Facial vein only
B) Pterygoid venous plexus via inferior orbital fissure; can also drain to cavernous sinus
C) Jugular vein directly only
D) Superior ophthalmic vein exclusively
Answer: B) Pterygoid venous plexus via inferior orbital fissure; can also drain to cavernous sinus

60. The annulus of Zinn provides the origin for which cranial nerve branches in the orbit?
A) All branches of V1 only
B) Oculomotor nerve (CN III), nasociliary branch of V1 runs within ring, abducent nerve (CN VI) passes through ring
C) Facial nerve branches only
D) Optic nerve only
Answer: B) Oculomotor nerve (CN III), nasociliary branch of V1 runs within ring, abducent nerve (CN VI) passes through ring

61. The levator aponeurosis attaches to which eyelid structure to transmit levator action?
A) Orbicularis oculi fibers only
B) Tarsal plate and skin of upper eyelid (forming crease)
C) Conjunctiva only
D) Lateral canthal tendon only
Answer: B) Tarsal plate and skin of upper eyelid (forming crease)

62. The infraorbital nerve is a branch of which cranial nerve division?
A) Ophthalmic (V1)
B) Maxillary (V2)
C) Mandibular (V3)
D) Facial nerve (VII)
Answer: B) Maxillary (V2)

63. The sphincter pupillae is innervated by which fiber type?
A) Sympathetic motor fibers via long ciliary nerves
B) Parasympathetic fibers from CN III via ciliary ganglion and short ciliary nerves
C) Sensory pain fibers from V1
D) Motor fibers from facial nerve
Answer: B) Parasympathetic fibers from CN III via ciliary ganglion and short ciliary nerves

64. The orbitalis muscle (Müller’s muscle) when present is located where and functionally does what?
A) In levator palpebrae to close eyelid forcibly
B) In orbital floor/infraorbital region; smooth muscle contributing to eyelid retraction and orbital tone under sympathetic control
C) In lateral rectus to abduct globe
D) In medial canthus to open lacrimal sac
Answer: B) In orbital floor/infraorbital region; smooth muscle contributing to eyelid retraction and orbital tone under sympathetic control

65. The optic chiasm receives which fiber arrangement relevant to visual fields?
A) Temporal retinal fibers cross only
B) Nasal retinal fibers cross; temporal fibers remain ipsilateral
C) All fibers cross at chiasm
D) Only fibers for inferior field cross
Answer: B) Nasal retinal fibers cross; temporal fibers remain ipsilateral

66. The orbital roof defect may allow spread of infection from the frontal sinus into the orbit causing:
A) Cavernous sinus thrombosis only
B) Subperiosteal orbital abscess and orbital cellulitis
C) Otitis media only
D) Pterygopalatine fossa abscess only
Answer: B) Subperiosteal orbital abscess and orbital cellulitis

67. The tendon of the inferior oblique inserts onto the:
A) Superior lateral sclera
B) Posterolateral inferior aspect of sclera (underneath lateral rectus insertion area)
C) Medial rectus sheath only
D) Lateral canthal tendon
Answer: B) Posterolateral inferior aspect of sclera (underneath lateral rectus insertion area)

68. The superior rectus muscle receives innervation from which division of CN III?
A) Inferior division only
B) Superior division (oculomotor nerve)
C) Trochlear nerve
D) Abducent nerve
Answer: B) Superior division (oculomotor nerve)

69. The infraorbital groove continues anteriorly as the infraorbital canal and opens at the:
A) Supraorbital notch
B) Infraorbital foramen
C) Mental foramen
D) Superior orbital fissure
Answer: B) Infraorbital foramen

70. The lacrimal apparatus drains tears into the inferior meatus via which structure?
A) Nasolacrimal duct opening at superior meatus
B) Nasolacrimal duct opening at inferior meatus
C) Lacrimal punctum to middle meatus directly
D) Maxillary ostium only
Answer: B) Nasolacrimal duct opening at inferior meatus

71. The ophthalmic artery gives off which branch that supplies the lateral orbit and eyelids?
A) Infraorbital artery only
B) Lacrimal artery (branch of ophthalmic artery)
C) Superior thyroid artery
D) Middle meningeal artery
Answer: B) Lacrimal artery (branch of ophthalmic artery)

72. The orbital apex syndrome involves lesions affecting cranial nerves II, III, IV, V1, and VI and typically presents with:
A) Only facial paralysis
B) Visual loss, ophthalmoplegia, and sensory loss in V1 distribution
C) Hearing loss only
D) Loss of tongue movement
Answer: B) Visual loss, ophthalmoplegia, and sensory loss in V1 distribution

73. The conjunctival fornix is the space between:
A) Cornea and iris only
B) Palpebral and bulbar conjunctiva (fold between eyelid and eyeball)
C) Eyelid margin and tarsal plate
D) Lacrimal sac and nasolacrimal duct
Answer: B) Palpebral and bulbar conjunctiva (fold between eyelid and eyeball)

74. The outer fibrous tunic of the eyeball comprises the sclera and:
A) Retina
B) Cornea
C) Choroid
D) Ciliary body
Answer: B) Cornea

75. The zonular fibers (suspensory ligament of lens) attach to which structure?
A) Iris only
B) Ciliary body (ciliary processes)
C) Corneal endothelium
D) Optic disc
Answer: B) Ciliary body (ciliary processes)

76. The orbital floor is vulnerable to fracture because it is formed largely by:
A) Dense frontal bone only
B) Thin orbital plate of maxilla and zygomatic bone (roof of maxillary sinus)
C) Sphenoid greater wing only
D) Ethmoid lamina only
Answer: B) Thin orbital plate of maxilla and zygomatic bone (roof of maxillary sinus)

77. The occulomotor nerve parasympathetic preganglionic fibers synapse in which ganglion for intraocular muscles?
A) Otic ganglion
B) Ciliary ganglion
C) Pterygopalatine ganglion
D) Superior cervical ganglion
Answer: B) Ciliary ganglion

78. The medial rectus muscle is primarily responsible for:
A) Elevation of globe
B) Depression of globe
C) Adduction of the globe (eye toward nose)
D) Abduction of the globe
Answer: C) Adduction of the globe (eye toward nose)

79. The orbital fracture causing infraorbital nerve injury will produce anesthesia of:
A) Cornea only
B) Upper cheek, lateral nose, lower eyelid, and upper lip (areas supplied by infraorbital nerve)
C) Forehead and scalp only
D) Lower teeth exclusively
Answer: B) Upper cheek, lateral nose, lower eyelid, and upper lip (areas supplied by infraorbital nerve)

80. The sclera’s vascular supply is mainly from branches of the:
A) Ophthalmic artery via posterior ciliary arteries (choroidal vessels)
B) Ophthalmic artery (posterior ciliary arteries supply sclera/choroid)
C) Facial artery alone
D) External carotid directly to sclera
Answer: B) Ophthalmic artery (posterior ciliary arteries supply sclera/choroid)

81. The lacrimal gland receives parasympathetic secretomotor fibers that travel via:
A) Ciliary ganglion → short ciliary nerves
B) Pterygopalatine ganglion → zygomatic nerve (V2) → communicating branch to lacrimal nerve (V1)
C) Otic ganglion → auriculotemporal nerve
D) Superior cervical ganglion → long ciliary nerves
Answer: B) Pterygopalatine ganglion → zygomatic nerve (V2) → communicating branch to lacrimal nerve (V1)

82. The inferior orbital fissure lies between the greater wing of sphenoid and the:
A) Frontal bone only
B) Maxilla and greater wing of sphenoid (and orbital surface of zygomatic)
C) Lacrimal bone and ethmoid only
D) Palatine bone and frontal bone
Answer: B) Maxilla and greater wing of sphenoid (and orbital surface of zygomatic)

83. The main refracting surface of the eye is the:
A) Lens only
B) Cornea (provides most refractive power)
C) Vitreous humor only
D) Sclera only
Answer: B) Cornea (provides most refractive power)

84. The orbital roof is separated from the anterior cranial fossa by which membrane/fascia layer?
A) Periorbita only
B) Periorbita (orbital periosteum) and thin bone; dura on cranial side
C) Tenon’s capsule only
D) Conjunctiva only
Answer: B) Periorbita (orbital periosteum) and thin bone; dura on cranial side

85. The motor root of the ciliary ganglion carries preganglionic parasympathetic fibers from:
A) Facial nerve directly
B) Oculomotor nerve (CN III)
C) Trigeminal nerve (V1)
D) Glossopharyngeal nerve (CN IX)
Answer: B) Oculomotor nerve (CN III)

86. The orbital roof sinus that can erode into the orbit if infected is the:
A) Maxillary sinus
B) Frontal (ethmoid can also contribute medially) sinus
C) Sphenoid sinus only
D) Inferior meatus
Answer: B) Frontal (ethmoid can also contribute medially) sinus

87. The superior oblique muscle causes which primary movement of the eye when the eye is adducted?
A) Elevation
B) Intorsion and depression (especially when eye is adducted)
C) Abduction only
D) Extorsion only
Answer: B) Intorsion and depression (especially when eye is adducted)

88. The ophthalmic division (V1) exits the cranial cavity through the:
A) Foramen ovale
B) Foramen rotundum
C) Superior orbital fissure (and partly via cavernous sinus region)
D) Infraorbital foramen
Answer: C) Superior orbital fissure (and partly via cavernous sinus region)

89. The pupillary light reflex efferent limb uses which nerve to constrict the pupil?
A) Trigeminal motor fibers
B) Oculomotor nerve parasympathetic via ciliary ganglion and short ciliary nerves
C) Facial nerve branch to orbicularis oculi
D) Sympathetic fibers via superior cervical ganglion
Answer: B) Oculomotor nerve parasympathetic via ciliary ganglion and short ciliary nerves

90. A lesion of the abducent nerve in the cavernous sinus will produce:
A) Ptosis only
B) Inability to abduct eye (lateral rectus palsy) and medial deviation (esotropia)
C) Loss of pupillary light reflex only
D) Loss of corneal sensation only
Answer: B) Inability to abduct eye (lateral rectus palsy) and medial deviation (esotropia)

91. The orbital fascia (periorbita) is continuous with which periosteal layer?
A) Periosteum of the face only
B) Periosteum lining the bones of the orbit (continuous with cranial periosteum at margins)
C) Dura only
D) Tenon’s capsule only
Answer: B) Periosteum lining the bones of the orbit (continuous with cranial periosteum at margins)

92. The choroid layer of the eyeball is vascular and lies between the retina and the:
A) Sclera (external) and retina (internal) — so between retina and sclera
B) Sclera (external) and retina (internal)
C) Cornea only
D) Lens only
Answer: B) Sclera (external) and retina (internal)

93. The extraocular muscle most commonly affected first in thyroid ophthalmopathy (Graves’ orbitopathy) is:
A) Lateral rectus
B) Inferior rectus
C) Superior rectus only
D) Superior oblique
Answer: B) Inferior rectus

94. The orbital floor provides the roof of which paranasal sinus?
A) Frontal sinus
B) Maxillary sinus
C) Sphenoid sinus
D) Ethmoid sinus only
Answer: B) Maxillary sinus

95. The nerve that supplies sensation to the tip of the nose is primarily a branch of:
A) Infraorbital nerve (V2)
B) External nasal branch of anterior ethmoidal nerve (branch of nasociliary, V1)
C) Facial nerve only
D) Mandibular nerve (V3)
Answer: B) External nasal branch of anterior ethmoidal nerve (branch of nasociliary, V1)

96. The pupillary dilator muscle is innervated by which fibers traveling in which nerves?
A) Parasympathetic via short ciliary nerves
B) Sympathetic fibers via long ciliary nerves (from superior cervical ganglion)
C) Sensory fibers via long ciliary only
D) Facial nerve secretomotor fibers
Answer: B) Sympathetic fibers via long ciliary nerves (from superior cervical ganglion)

97. The primary drainage route for the conjunctiva and eyelids is via which vein to reach the cavernous sinus?
A) Facial vein only via angular vein → ophthalmic veins → cavernous sinus
B) Angular vein → superior ophthalmic vein → cavernous sinus (also communication via inferior ophthalmic vein to pterygoid plexus)
C) External jugular directly to cavernous sinus
D) Internal maxillary vein directly to cavernous sinus
Answer: B) Angular vein → superior ophthalmic vein → cavernous sinus (also communication via inferior ophthalmic vein to pterygoid plexus)

98. The orbital branch supplying the frontal sinus and anterior cranial fossa enters orbit via which opening?
A) Infraorbital foramen
B) Supraorbital notch/foramen (supraorbital nerve branch of V1)
C) Optic canal
D) Inferior orbital fissure
Answer: B) Supraorbital notch/foramen (supraorbital nerve branch of V1)

99. The posterior ciliary arteries, branches of the ophthalmic artery, supply which ocular structure primarily?
A) Cornea
B) Choroid and outer retina (via short posterior ciliary arteries)
C) Lens capsule only
D) Conjunctiva only
Answer: B) Choroid and outer retina (via short posterior ciliary arteries)

100. The orbital diaphragm (orbital septum) separates preseptal from postseptal spaces and is clinically important because preseptal cellulitis spares:
A) Globe and orbital contents (postseptal infection involves globe) — which is true
B) Orbital contents; preseptal cellulitis does not involve the orbit itself
C) Cavernous sinus always
D) Lacrimal gland always
Answer: B) Orbital contents; preseptal cellulitis does not involve the orbit itself