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Neuro Exam II > Orbit and Eye - SRS > Flashcards

Orbit and Eye - SRS Flashcards

1
Q

What are the bones of the orbit?

A
  1. Frontal
  2. Maxilla
  3. Sphenoid
  4. lacrimal
  5. ethmoid
  6. palatine
  7. zygomatic
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2
Q

What makes up the apex of the orbit?

A

lesser wing of the sphenoid, surrounding the optic canal

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3
Q

What makes up the base of the orbit?

A
  1. formed by the orbital margin and orbital opening
    a. Orbital margin is formed by frontal, zygomatic, and maxilla bones.
    b. Orbital margin is thickened to provide support and protection to the eyeball.
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4
Q

What makes up the roof of the orbit?

A

a. Frontal bone and some sphenoid – separates orbit from anterior cranial fossa
b. Fossa for lacrimal gland

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5
Q

What makes up the floor of the orbit?

A

a. Maxilla bone – separates orbit from maxillary sinus
b. Zygomatic bone
c. Palatine bone

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6
Q

What makes up the medial wall of the orbit?

A

a. Ethmoid bone
b. Lacrimal bone
c. Maxilla bone
d. The lacrimal fossa; houses the medial portion of the lacrimal system.

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7
Q

What makes up the lateral wall of the orbit?

A

a. Zygomatic bone
b. Sphenoid – greater wing

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8
Q

A massive zygomaticomaxillary complex fracture, or direct blow to the orbit may cause a rapid increase in intracranial pressure which could lead to?

A

An orbital blow-out fracture:

The thin orbital floor is fractured.

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9
Q

What can happen in severe comminuted fractures of the orbital floor?

What are clinical signs that this has happened?

A

The soft tissue may herniate into the underlying maxillary paranasal sinus.

  1. diplopia
  2. infraorbital nerve parasthesia
  3. enopthalmos,
  4. edema
  5. ecchymosis
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10
Q

Since the orbital margins are strong, where do most fractures of the orbit occur?

A

At sutures between bones

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11
Q

Malignant tumors originating in the sphenoidal and ethmoidal sinuses, middle cranial, or infratemporal fossa can erode through the thin walls of the orbit or pass directly through foramina.

What can happen as a result of this?

A

Tumors can compress the orbital contents, and may cause exophthalmos.

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12
Q

When a person starves, the eyes often become sunken in, (enopthalmos). Why is this?

A

Loss of orbital fat

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13
Q

What is the periorbital fascia continuous with?

A

a. Continuous with periosteal dura at optic canal and superior orbital fissure.
b. Continuous with the orbital septum anteriorly.
c. Continuous with muscular fascias of extraocular eye muscles.

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14
Q

The medial and lateral check ligaments attach to medial and lateral orbital walls. What is the function of these ligaments?

A

a. Limit abduction and adduction of the eye.
b. Prevent posterior retraction of the eyeball by the rectus muscles.

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15
Q

What are the glands associated with the eyelids?

A
  1. Tarsal (Meibomian) glands (sebaceous glands)
  2. Glands of Zeis (smaller sebaceous glands)
  3. Glands of Moll (sweat gland)
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16
Q

Glands of the eye may become obstucted and inflamed.. What can this lead to?

A

chalazion (meibomian cyst) or a hordeoum (cyst of eyelash glands)

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17
Q

What muscles are associated with the eyelids?

A
  1. Orbicularis oculi
  2. Levator palpebrae superioris
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18
Q

What is the impact of CN VII impairment on the eyelid?

A
  • Eyelid cannot close completely due to loss of innervation to orbicularis oculi.
  • The inferior eyelid tends to fall away from the eyeball and result in dryness and irritation of the cornea and sclera.
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19
Q

What is the innervation of levator palperbrae superioris?

A

CN III

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20
Q

What happens to the eyelids with impairment of CN III?

A

Inability to open the upper eyelid (ptosis)

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21
Q

Loss of sympathetic innervation to the head is what syndrome? How does this present regarding the eyelids?

A

Horner’s syndrome

ptosis

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22
Q

What are the structures associated with the conjunctiva?

A
  • Palpebral conjunctiva – epithelium of internal eyelid
  • Bulbar conjunctiva – outer epithelium of sclera
  • Conjunctival sac – between palpebral and bulbar conjunctiva; opens at palpebral fissure.
  • Conjunctival fornices (superior and inferior) are formed where bulbar and palpebral conjunctiva are continuous.
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23
Q

What are the components of the lacrimal apparatus?

A
  1. Lacrimal gland
  2. lacrimal cannaliculi
  3. lacrimal sac
  4. nasolacrimal duct
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24
Q

The lacrimal gland secretes lacrimal fluid, a watery, serous secretion into the conjunctival sac. What is the function of this fluid?

A

Lacrimal fluid keeps sclera and cornea moist and contains an antibacterial agent for protection.

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25
Q

What is the opening to the lacrimal cannaliculi?

A

Lacrimal punctum

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26
Q

Describe the flow of tears…

We should all be familliar with this by now due to medical school…

A

lacrimal gland –> conjunctival sac –> surface of eye –> lacrimal papillae with puncta –> cannaliculae –> lacrimal sac –> nasolacrimal duct

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27
Q

What causes corneal neovascularization?

A

Blood vessels grow into the corneal stroma secondary to hypoxia

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28
Q

What are the three tunics that the eyeball posesses?

A
  1. External fibrous tunic
  2. Middle vascular tunic
  3. Inner neural tunic
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29
Q

Should the cornea have vessels in it?

A

No

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30
Q

What provides most of the eye’s refractile capabilities?

A

Cornea

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31
Q

What is the function of the sclera?

A
  1. Structural support for the eye
  2. Muscle attachment
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32
Q

What are the components of the middle vascular tunic?

A
  1. Choroid
  2. Iris
  3. Ciliary body
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33
Q

The choroid contains melanocytes which produce melanind to absorb photons of light. What is the primary function of the choroid?

A

Provides vascular supply to the fibrous layer and outermost layers of retina.

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34
Q

The central aperture of the iris forms the pupil, and the iris controls the amount of light entering the pupil. By what muscles and innervations does this control occur?

A
  1. Sphincter pupillae
    • Reduces diameter of pupil (miosis) to decrease light entering eye.
    • Parasympathetic innervation (CN III).
  2. Dilator pupillae
    • Increases diameter of pupil (mydriasis) to increase light entering eye.
    • Sympathetic innervation.
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35
Q

The ciliary body has what components?

A

Ciliary processes

Ciliary muscle

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36
Q

What do the ciliary processes do?

A

Secrete aqueous humor into posterior chamber.

Attach to lens, enabling musculature to perform accomodation

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37
Q

What is the innervation of the ciiary muscle?

A

Oculomotor (parasympathetic)

38
Q

What are the six components of the inner neural tunic? What else is this tunic known as?

A

The retina

  1. Rods/cones
  2. ganglion cells forming the optic nerve
  3. Ora Serrata
  4. Optic Disc
  5. Macula Lutea
  6. Fovea centralis
39
Q

What is the ora serrata?

A

The anterior termination of the retina

40
Q

What kind of photoreceptive cells are located on the optic disc?

A

None, this is a blind spot.

41
Q

What is the macula lutea?

A

a yellow-pigmented zone located about 2.5 mm lateral to optic disk.

42
Q

What is the fovea centralis?

A
  • oval depression located in the central of the macula.
  • Site of greatest visual acuity due to density of cone cells.
43
Q

What is the blood supply of the neural part of the retina?

A

Central retinal artery

44
Q

What is the blood supply to the pigmented epithelium and rod/cone layer of the retina?

A

Choroid vessels

45
Q

Retinal detachment occurs when the pigmented epithelium separates from the underlying rods and cones layer. What can this cause if not quickly corrected?

A

Blindness, due to loss of metabolic support and blood supply to the rods and cones.

46
Q

What is presbyopia?

A

Hardening (loss of elasticity) of the lens - leading to inability to accommodate and focus on near objects

47
Q

Cataracts develop when proteins of the lens aggregate, producing…

A

An opaque lens

48
Q

The vitreous body is between the lens and posterior surface of the eye. What is it filled with?

A

Vitreous humor - a transparent, refractile jelly-like substance.

49
Q

What are the aqueous chambers?

Where are they located?

A

Anterior - between cornea and iris

Posterior - between iris and lens

50
Q

The aqueous humor is a refractive fluid filling the anterior and posterior chambers. Produced in the posterior chamber by ciliary processes, it flows into the anterior chamber via the pupil.

How does it drain?

A

Drains to venous system via the scleral venous sinus (Canal of Schlemm) at the iridocorneal angle.

The scleral venous sinus is covered by a trabecular meshwork (endothelial lined spaces) which helps drain aqueous humor.

Scleral venous sinus drains to vorticose and anterior ciliary veins.

51
Q

What sources are the structures of the eye derived from?

A
  1. Neural ectoderm
  2. Surface ectoderm
  3. Mesenchyme
52
Q

The neural ectoderm is also known as the optic cesicles, and is derived from evaginations of the forebrain neuroectoderm. What does it form?

A

Retina, optic nerve

53
Q

What does the surface ectoderm form in the eye?

A

Forms the lens

54
Q

What does the mesenchyme form in the eye?

A

fibrous (sclera, cornea) and vascular (choroid, iris, ciliary body) layers

55
Q

What do the outer and inner layers of the optic cup form?

A
  1. Outer layer of optic cup – pigmented layer of retina
  2. Inner layer of optic cup – all neural layers of retina
56
Q

What does congenital retinal detachment arise due to?

A

Inner and outer layer of optic cup fail to fuse. Separationg of pigmented and neural layers of retina. This will result in blindness if not attached.

57
Q

What is the choroid derived from?

A

Vascular layer of mesenchyme surrounding optic cup

58
Q

What separates the anterior and posterior aqueous chambers until ~ week 15?

A

Iridopupillary membrane

59
Q

How does congenital atresia of the pupil occur?

A

Iridopupillary membrane fails to degenerate.

60
Q

What does colomba result from?

A

Failure of the choroid fissure to fuse during week 7 of development. (may also involve retina)

61
Q

What are the sclera and cornea derived from?

A

A. fibrous layer of mesenchyme surrounding optic cup.

62
Q

How do the aqueous and vitreous chambers of the eye form?

A
  1. The eye chambers form in areas of cell death within eyeball.
  2. Vitreous humor is likely derived from neural crest cells.
63
Q

From what do the extrinsic eye muscles form?

A

Mesoderm of myotomes

64
Q

The ophthalmic artery arises from the internal carotid artery and enters the orbit via the optic canal. What are the branches it gives off?

A
  1. Central retinal artery
  2. Short posterior ciliary
  3. Long posterior ciliary
  4. Anterior ciliary arteries
  5. Lacrimal
  6. Supraorbital
  7. Posterior ethmoidal
  8. Anterior Ethmoidal
  9. Medial Palpebral
  10. Supratrochlear
  11. Dorsal Nasal
65
Q

What do vorticose veins drain?

A

Choroid

Ciliary body

Iris

66
Q

Where does the central retinal vein drain?

A

Directly to cavernous sinus

67
Q

Where do the superior and inferior ophthalmic veins drain?

A

Cavernous sinus and pterygoid venous plexus

68
Q

If a patient develops thrombophlebitis of the cavernous sinus, what can happen?

A

May send a clot to the central retinal vein, leading to vision loss.

69
Q

How can increased intracranial pressure affect the eye?

A

Increased intracranial pressure can affect the eye due to the fact that the meninges and CSF continue along the optic nerve. Thus, the optic nerve, central retinal artery, and central retinal vein can be compressed and occluded.

Occlusion of the central retinal vein can cause papilledema (retinal edema).
Compression of the optic nerve can cause blindness.
Retinal artery occlusion can also cause blindness due to loss of blood supply to retina.

70
Q

What are the movements of the eye?

A

A.Adduction – movement of the pupil towards midline (toward nose)

B.Abduction – movement of pupil laterally (toward ear)

C.Elevation – movement of pupil superiorly.

D.Depression – movement of pupil inferiorly

E.Extortion – superior pole of eyeball rotated laterally.

F.Intortion – superior pole of eyeball rotated medially.

71
Q

Name the extraocular eye muscles

A
  1. Medial rectus
  2. Lateral rectus
  3. Superior rectus
  4. Inferior rectus
  5. Inferior oblique
  6. Superior Oblique
72
Q

What does the medial rectus do?

What is its innervation?

How is integrity tested?

A

Adducts eye

CN III

Eye is held in abducted position, loss of adduction

73
Q

What does the lateral rectus do?

Innervation?

How is integrity tested?

A

abducts the eye

CN VI

Eye is held in adducted position, loss of abduction

74
Q

What does the superior rectus do?

Innervation?

How do we determine integrity?

A

Elevates, adducts, intorsion

CN III

Weakness of elevation, loss of elevation when eye is fully abducted

75
Q

What is the action of the inferior rectus?

Innervation?

How do we test integrity?

A

Depresses, adducts, extorsion

CN III

Weakness of depression, loss of depression when eye is fully abducted

76
Q

What is the action of the inferior oblique?

Innervation?

How do we determine integrity?

A

Elevates, Abducts, extorsion

CN III

Weakness of elecation, loss of elevation when eye is fully adducted

77
Q

What is the action of the superior oblique?

Innervation?

How do we determine integrity?

A

Depresses, abducts, intorsion

CN IV

Weakness of depression, loss of depression when eye is fully adducted

78
Q

What are the GSE nerves of the orbit?

A

III

IV

VI

79
Q

The oculomotor nerve has an inferior and a superior division. What does the inferior division carry?

A

Preganglionic parasympathetic fibers to the ciliary ganglia

80
Q

What do we see due to oculomotor palsy?

A

a. Ptosis or complete closure of eye (loss of levator palpebrae superioris)
b. Diplopia
c. Eye will be abducted and depressed (down and out)
d. Dilation of pupil (due to loss of sphincter pupillae muscle)
e. Loss of accommodation (due to loss of ciliary muscle)

81
Q

What do we see due to Trochlear nerve palsy?

A

a. Diplopia
b. Eye will be slightly elevated and adducted.
c. Loss of depression when eye fully adducted.

82
Q

What do we see with Abducent nerve palsy?

A

a. Diplopia
b. Loss of eye abduction.

83
Q

What are the branches of the ophthalmic division of the trigeminal nerve?

A
  1. Nasociliary
  2. Frontal
  3. Lacrimal
84
Q

What branches does the nasociliary nerve give off?

A
  1. Short ciliary nerves – arise from ciliary ganglia on lateral side of optic n; carry postganglionic sympathetic, parasympathetic, and sensory fibers.
  2. Long ciliary nerves – arise from nasociliary nerve on medial side of optic n; carry postganglionic sympathetic fibers, sensory fibers.
  3. Posterior ethmoidal nn. – to ethmoidal air cells, dura.
  4. Anterior ethmoidal nn. – to ethmoidal air cells, nasal cavity, dura; terminates as external nasal nerve.
  5. Infratrochlear n. – exits orbit at medial angle; sensory to skin at root of nose, eyelids, palpebral conjunctiva, lacrimal sac.
85
Q

What nerves does the frontal nerve split into?

A
  1. Supratrochlear nerve
  2. Supraorbital nerve
86
Q

What does the lacrimal nerve do>

A
  1. Sensory to lacrimal gland; lateral portion of superior eyelid.
  2. Carries postganglionic parasympathetic and sympathetic fibers to lacrimal gland
87
Q

Where are the preganglionic cells for the parasympathetics to the sphincter pupillae and ciliary muscles located?

A

Edinger-westphal nucleus

88
Q

The ciliary ganglion is located between the lateral rectus muscle and the optic nerve. What are its three roots?

A

a. Sensory root from nasociliary nerve
b. Parasympathetic motor root from oculomotor nerve
c. Sympathetic motor root from the internal carotid plexus

89
Q

Describe the following components of the pupillary light reflex:

  1. Function –
  2. Afferent nerve –
  3. Efferent nerve –
  4. Testing method -
  5. normal result -
  6. Direct response –
  7. Consensual response –
A
  1. Function – protect eye from excessive light exposure
  2. Afferent nerve – CN II (vision)
  3. Efferent nerve – CN III (GVE-P to sphincter pupillae m)
  4. Testing methog - Shine light in eye (CN II).
  5. Normal result - Both pupils constrict (CN III).
  6. Direct response – ipsilateral eye constricts.
  7. Consensual response – contralateral eye constricts.
90
Q

Describe the following components of the corneal reflex:

  1. Function –
  2. Afferent nerve –
  3. Efferent nerve –
  4. Testing method -
  5. normal result -
  6. Direct response –
  7. Consensual response –
A
  1. Function – protect eye from foreign objects
  2. Afferent nerve – CN V1 (general sensation to eye; pain)
  3. Efferent nerve – CN VII (orbicularis oculi)
  4. Puff of air on eye (or directly touching cornea) stimulates CN V1.
  5. Both eyes blink due to contraction of orbicularis oculi (CN VII).
  6. Direct and consensual responses.
91
Q

Describe the following components of the accomodation reflex:

  1. Function –
  2. Afferent nerve –
  3. Efferent nerve –
  4. Testing method -
  5. normal result -
  6. Direct response –
  7. Consensual response –
A
  1. Function – view near objects
  2. Afferent nerve – CN II (vision)
  3. Efferent nerve – CN III (GSE and GVE-P)
  4. Looking from a distant object to a near object (CN II).
  5. Direct and consensual responses.
92
Q

What three events occur in the accomodation reflex?

A

a. Ciliary muscles contract, cause rounding of lens (accommodation) (CN III; GVE-P)
b. Pupils constrict (CN III; GVE-P)
c. Eyes adduct (CN III; GSE)

Neuro Exam II (13 decks)

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