1 - Zill - Orbit Flashcards

1
Q

Bones of the Orbit

A
  1. Roof - Frontal
  2. Floor - Maxillary
  3. Medial Wall - Maxillary, Lacrimal, Ethmoid, Frontal, Sphenoid Bones
  4. Lateral Wall - Zygomatic, Sphenoid
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2
Q

What does the orbit serve as a highways for?

A

Nerves and Vessels to Face, Scalp, and Nasal Cavity

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3
Q

Optic Canal

A

In base of Lesser Wing of Sphenoid

Contents:

Optic Nerve (CN II)

Opthalmic Artery

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4
Q

Superior Orbital Fissure

A

Between Greater and Lesser Wings of Sphenoid

Contents:

Cranial Nerves III, IV, V1, VI (3, 4, 5.1, 6)

Ophthalmic Veins

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5
Q

Supraorbital Notch (Foramen)

A

In frontal bone

Contents:

Supraorbital Nerve (From V1)

Supraorbital Artery (From Ophthalmic A.)

Supraorbital Vein (From Opthalmic V.)

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6
Q

Infraorbital Foramen

A

In maxillary bone

Contents:

Infraorbital Nerve (From V2)

Infraorbita Artery (From Maxillary Artery)

Infraorbita Vein

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7
Q

Anterior and Posterior Ethmoidal Foramina

A

Between Ethmoid and frontal bones (back of the eye)

Connect Orbit and Nasal Cavities

Contains:

Anterior and Posterior Ethmoidal Nerves (branch of V1)

Anterior and Posterior Ethmoidal Arteries (branch of Ophthalmic)

Anterior and Posterior Ethmoidal Veins (branch of Ophthalmic)

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8
Q

Opening of Nasolacrimal Duct

A

In Maxillary, Lacrimal, and Inf. Nasal Concha

Contains:

Membraneous Nasolacrimal Duct

Tears

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9
Q

Stye (Horde’olum)

A

Obstruction or Infection of Sebaceous Gland in subcutaneous layer

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10
Q

Eyelids (Palpebrae)

Layers

A

Layers:

Skin - Contains eyelashes, openings of sebaceous, sweat glands

Subcutaneous Layer - Connective tissue, contains sebaceous glands (Stye here)

Tarsal Plate - Fibrous CT skeleton of eyelid (Chalazion here)

Orbital Septum - CT layer continuous with periosteum of orbit

Conjuctiva - Clear membrane covering inside of lide, fuses to sclera (Conjuctiva or “Pinkeye”)

Muscles:

Orbicularis Oculi (palpebral part) - Closes eye, Cranial Nerve 7

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11
Q

What can occur if Orbicularis Oculi is paralyzed?

What nerve innervates this?

A

Cornea can become damaged, as the eyelid does not function

Cranial Nerve VII

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12
Q

Chalazion

A

Obstruction of Tarsal (meibomian) Gland in eyelid

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13
Q

Levator Palpebrae Superioris

Action?

Innervation?

Clinical?

A

Action: Lift upper eyelid

Innervation:

Skeletal muscle part - CN III

Smooth Muscle Part - Sympathetics

Clinical: Eyelid Droop, damage to CN III or Sympathetics

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14
Q

Conjuctivitis (Pinkeye)

A

Inflammation of Conjunctiva

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15
Q

Lacrimal Gland

Action?

**Innervation?**

A

Action: Superolateral orbit, opens by ducts through conjunctiva to superior fornix, constantly produces tears

**Innervation: Cranial Nerve VII**

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16
Q

Facial Nerve and Lacrimal Duct:

Block VII?

Pressure/Irritate VII?

A

Block - Decrease tears

Pressure/Irritate - Excessive Tears

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17
Q

Human Development - Obstructed Nasolacrimal Duct

A

Failure of duct to canalize, tears drain over lower eyelid to face

Opened surgically for tears to drain to nasal cavity

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18
Q

Medial and Lateral Check Ligaments

A

Prevent Excessive Rotation of eye

19
Q

Three Structural Layers of Eye

A
  1. Fibrous Layer: Sclera, Cornea
  2. Vascular Layer: Iris, Ciliary Body, Choroid
  3. Retina
20
Q

Sclera

A

Tough, smooth white connective layer

Muscles attach here, fuses with dura posteriorly and cornea anteriorly

21
Q

Cornea

A

Avascular, aids in focusing light

Irregularities: Astigmatism

22
Q

Blood Supply to Orbit

A

Ophthalmic Artery

Major Branches:

Posterior Ciliary Arteries (Long and Short)

Central Artery of Retina

23
Q

Blood Supply to Eye

A
  1. Posterior Ciliary Arteries - pierce sclera, blood to choroid, photoreceptors
  2. Central Artery of Retina - pierce Optic Nerve, blood to neural retina; end artery (no anastomoses)
24
Q

Choroid

A

Highly vascular, pigmented, provides O2, nutrients to photoreceptors

25
Q

Vascular Layer of Eye (Uveal Tract [Uvea])

A

Choroid, Ciliary Body, Iris

26
Q

Retina

Blood Supply?

Clinical?

A

Contains Rods and Cones

Blood: Central Artery of Retina (br. of Ophthalmic A.); no anastomoses

Clinical: Occlusion can result in blindness

27
Q

CRAO (Central Retinal Artery Occlusion)

What can slightly prevent this?

A

Most common cause is Carotid Artery atherosclerosis; if complete blockage = blind in one eye

Ciliary Arteries can supply retina in 20% of people

28
Q

Subarachnoid Space and CSF

Papilledema

A

Dura and Subarachnoid space extends to back of eyeball around Optic Nerve; Increase in CSF Pressure can affect vision

  • Slow onset, headaches
  • Papilledema = Swelling of Optic Disc
29
Q

Ciliary Body

Muscle Attachment?

Contracted vs Relaxed?

Control?

A

Ciliary Muscles - smooth muscles that attach suspensory ligaments of lens; controls thickness of lens

- - -

Far Sight: Muscles Relaxed - Tight Ligaments - Flat Lens

Near Sight: Muscles Contracted - Loose Ligaments - Thick Lens

Lens is thickened (more power) for viewing objects close up, under Parasympathetic Control - III (Short Ciliary Nerves)

30
Q

Iris

***Pupil Dillation Control?***

A

Iris - Pigmented contractile layer with smooth muscles surrounding pupil

Constrictor Pupil - Circular smooth muscle - Parasympathetics (CN III)

Dilator Pupil - Radial smooth muscle - Sympathetics

IF ONE IS BLOCKED, OTHER WINS!

“ParaConstrictor - Cranial Nerve III”

31
Q

Extraocular Muscles:

Superior / Inferior Rectus

Lateral / Medial Rectus

Superior / Inferior Oblique

A

Superior / Inferior Rectus - Up / Down

Lateral / Medial Rectus - Lateral / Medial (will be opposite for eyes for coordinated L/R movements)

Superior / Inferior Oblique - Superior act through trochlea, Inferior to floor of orbit (rotate eyes)

32
Q

Voluntary Eye Movements

A

Adduct - Move medially

Abduct - Move laterally

Raise - Move superiorly

Lower - Move inferiorly

33
Q

Involuntary Eye Movements

A

Rotation

Involuntary when tilt head

Medial Rotate - Intorsion

Lateral Rotate - Extorsion

34
Q

Origins of Extraocular Muscles?

A

All but Inferior Oblique take origin from Tendinous Ring

Inferior Oblique takes origin from Floor of Orbit

35
Q

Medial and Lateral Rectus

Action?

Innervation?

A

Lateral Rectus

Action: Abduct Eye

Innervation: Cranial Nerve VI

- - -

Medial Rectus

Action: Adduct Eye

Innervation: Craial Nerve III

36
Q

Superior and Inferior Rectus

Action?

Innervation?

A

Superior Rectus

Action: Raise, Adduct, Medial Rotate

Innervation: Cranial Nerve III

- - -

Inferior Rectus

Action: Lower, Adduct, Lateral Rotate

Innervation: Cranial Nerve III

37
Q

Superior and Inferior Oblique

Action?

Innervation?

A

Superior Oblique

Action: Lower, Abduct, Medial Rotate

Innervation: Cranial Nerve IV

“Like muscle on nose”

Inferior Oblique

Action: Raise, Abduct, Lateral Rotate

Innervation: Cranial Nerve III

“Like muscle on ear”

38
Q

Draw the eye movements diagram.

A
39
Q

Clinical:

Damage to Abducens Nerve (CN VI)

A

At Rest: Medial Strabismus (cross-eyed) due to damage/paralyze Lateral Rectus

Nothing is “pulling” the eye lateral, so it will be pulled medial by resting eye tonus

40
Q

Clinical:

Damage to Trochlear (CN IV) Nerve

A

Symptoms:

Inability to turn eye down and out

Head Tilt (to counter eye lateral rotation at rest)

Difficulty walking down stairs

41
Q

Clinical:

Oculomotor (CN III) Nerve Damage

A

At Rest:

1 - Lateral Strabismus (wall-eyed) - due to paralyzed medial rectus

  1. Ptosis - Drooping eyelid, paralyze Lev. Palpebrae Superioris
  2. Dilated Pupil (mydriasis) - Paralyze Pupillary Constrictor`
42
Q

Ciliary Ganglion - Parasympathetics of what?

Travel with?

Innervate?

Clinical Damage?

A

Parasympathetics of Oculomotor (CN III)

Travel in Short Ciliary Nerves

Innervate Ciliary Muscles, Constrictor Pupillae

Clinical Damage to Short Ciliary Nerves: Dilated “Blown” Pupil = Mydriasis

43
Q

Trigeminal Nerve

Types?

A

V1 - Somatic Sensory

V2 - Somatic Sensory

V3 - Somatic Sensory and Branchiomotor

44
Q
A