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Neuroscience I (Exam 2) > The Orbit > Flashcards

The Orbit Flashcards

1
Q

List the 6 bones that make up the orbit.

A
  1. Frontal
  2. Ethmoid
  3. Greater Wing of Sphnoid Bone
  4. Lacrimal
  5. Zygomatic
  6. Maxillary
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2
Q

Which strucrures are going to be running in the:

  • Optic Canal
  • Superior Orbital Fissure
  • Inferior Orbital Fissure
A
  • Optic Canal: CN II and Opthalmic Artery
  • Superior Orbital Fissure: CN III, IV, V1, XI and Superior Opthalmic Vein
  • Inferior Orbital Fissure: CN V2 (Infraorbital Nerve and Zygomatic Nerve) and Inferior Opthalmic Vein
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3
Q
A
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4
Q
A

C. Maxillary Sinus

In “Blow-Out Fractures” you will rupture the floor of the eye socket and the eye will herniate down into the Maxillary Sinus

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5
Q
A

B. Le Forte II

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6
Q

Differentiate between the various types of Le Forte Fractures.

A
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7
Q

Describe the different layers in the eye.

A
  • *1. Protective**
    a. Sclera
    b. Cornea

2. Vascular (aka Uvea)
a. Choroid
b. Ciliary body (thick portion on end of choroid)
c. Iris (Gives you color in your eyes)
**** Anterior Uveitis: Probably in the Ciliary Body or Iris
**** Posterior Uveitis: Probably in the Choroid

  • *3. Nerual (aka Sensory)**
    a. Neural Retina
    b. Pigmented Retina (contains melanin)
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8
Q
A

D. Iris

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9
Q
A

B. Meningeal Dura (Aka Dura Mater)

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10
Q

What is the cause of Papilledema?

A
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11
Q

What is the area with the most concentrated cones in the Macula?

A

Fovea!

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12
Q

Describe how tears are drained from the eye.

A

Lacrimal Gland –> Lacrimal Ducts –> Puncta –> Lacrimal Canals –> Lacrimal Sac –> Nasolacrimal Duct –> Posterior Nasal Meatus

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13
Q
A

A. Vidian Nerve (Goes to the Pterygopalatine Ganglion)

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14
Q

List the various layers of the eye.

A
  1. Skin
  2. Orbicularis Oculi
  3. Fat
  4. Orbital Septum –> Fascia that supports all of the muscles in the eye; when you have a black eye, you will not have cross-over of the blood due to the connections!
  5. Levator Papebrae Superioris (LPS) –> Elevates the Eyelid
  6. Conjunctiva –> Extension of the Sclera
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15
Q

What is the function of the Orbicularis Occuli Muscle (specifically the Palpebral Portion)?

Why is it clinically important?

A

Function: CLOSE the eyelids and DRAIN the tears

Bell’s Palsey and the Corneal Reflex

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16
Q

Differentiate between the Levator Palepbrae Superioris Muscle and Muller’s Smooth Muscle in regrards to innervation and function.

A

LPS –> OPEN eyelid, CN III

Muller’s Smooth Muscle –> DILATE the pupil, Sympathetic Fibers

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17
Q
A

D. Muller’s Muscle

*** Patient is experiencing Horner’s Syndrome

PAM (Ptosis, Anhydrosis, Miosis) is HORNY!!!

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18
Q

Differentiate between complete and partial Ptosis.

A
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19
Q

List the 6 Extraocular Muscles with their function and innervation.

A
  1. Superior Oblique –> Goes through the trochlea and attaches to the top of the eye; Medially and DOWN
  2. Superior Rectus –> Laterally and UP
  3. Medial Rectus
  4. Lateral Rectus –> Lateral
  5. Inferior Rectus –> Laterally and DOWN
  6. Inferior Oblique –> Medially and UP

*** SO4 - LR6 - Rest CN 3

20
Q

Describe the presentation of the Oculomotor Palsey.

A

Parasympathetics are going to come from the Oculomotor Nerve (CN III)!

If you have complete PTOSIS, you can suspect that CN III is INVOLVED!

21
Q

Differentiate between the various Palseys:

III

IV

VI

A
22
Q

Which nerves are in the Ponto-Medullary Junction?

A

CN VI, VII, and VII

23
Q

Describe the pneumonic “SLIM”

A

Superior Colliculus - Lateral Geniculate Body
Optic Nerve - Chiasm - Tract –> Lateral Geniculate Body –> Brachium of Superior Colliculus –> Superior Colliculus

Inferior Colliculus - Medial Geniculate Body

24
Q

Describe the various relationships with the Optic Nerve.

Which artery is going to travel with the Optic Nerve through the Optic Canal?

Which embryological structure of the Brain is CN II coming from?

A

Optic Chiasm - Infundibular Stalk of Pituitary - Mammilary Bodies

*** Opthalmic Artery

*** Diencephalon

25
Q

Discuss the path of the Oculomotor Nerve.

What is its function?

A

Comes off of MIDBRAIN and goes through the SUPERIOR ORBITAL FISSURE

Function:

  1. Extraoccular Muscles –> SR, IR, MR, IO
  2. Levator Palpebrae Superioris
  3. Parasympathetics via the Short Ciliary Nerves (Ciliary Ganglion)
26
Q

Anatomically, why is the Oculomotor Nerve considered a big Landmark?

A

Splits CEREBELLAR and CEREBRAL vasculature supply (between the Supeior CEREBELLAR Artery and Posterior CEREBRAL Artery)

27
Q

Describe the path of the Trochlear Nerve (CN IV).

What is its function?

A

*** TRICKY TROCHLEAR comes off of the POSTERIOR side of the MIDBRAIN and passes through the SUPERIOR ORBITAL FISSURE

Function: DEPRESS the eye from an ADducted position (Superior Oblique Muscle)

28
Q

Describe the path of the Trigeminal Nerve.

A

“Standing Room Only”

V1 (Opthalmic) - exits through SUPERIOR ORBITAL FISSUE (All Sensory)

V2 (Maxillary) - Exits through FORAMEN ROTUNDUM (All Sensory)

V3 (Mandibular) - Exits through FORAMEN OVALE (BOTH Motor and Sensory)

29
Q

What are the various Branches off of V1?

What are the various functions?

What are the Clinical Manifestations of V1?

A

“NFL”

  1. Nasociliary Nerve
  2. Frontal Nerve
  3. Lacrimal Nerve

Functions:

  • Lacrimal Gland (Parasympathetic Postganglionic Fibers from Sphenopalatine Ganglion through Lacrimal Nerve)
  • Sensory of Forehead to the TIP of the NOSE (including Cornea)

**** CORNEAL REFLEX –> Touch the eye and V1 will sense it!
**** HERPES ZOSTER of the Eye –> Irritation of the eye and forehead due to the path of V1!

30
Q

Describe the Pathway of the Abducens Nerve.

A

Comes off at the METENCEPHALON (medial Ponto-Medullary Junction) and goes through te SUPERIOR ORBITAL FISSURE

Function: ABducts the eye (Lateral Rectus Muscle)

31
Q

Describe the Corneal (Blink) Reflex.

A

IN by V1, OUT by 7

Afferent –> Nasociliary Nerve (V1)

Efferent –> Zygomatic Branch of VII

Effector –> Orbicularis Oculi Muscle (BOTH Eyes will Blink!)

32
Q

Describe the Direct Light Reflex.

A

IN by II, OUT by III

Posterior Commisure is SUPER IMPORTANT because it allows us to cross over and both eyes will then constrict!

33
Q

Differentiate between Miosis and Mydriasis.

A
  • *Miosis**: CONSTRICTION aka Parasympathetics
  • Spincter Pupillae and Ciliary Muscle
  • *Mydriasis**: DILATION aka Sympathetics
  • Dilator Papillae and Superior Tarsal Muscle (Mueller’s Muscle)
34
Q

What is the TRIAD for NEAR vision?

A
  1. Miosis (CONSTRICTION aka Parasympathetics)
  2. Thickening of Lens –> Contracting Ciliary Body will relax Zonular Fibers and the Lens will become THICK!
  3. Convergence of Gaze –> Both eyes are looking @ a single object
35
Q
A

A. Pretectum

  • Accomodation is going to be controlled by the Cortical Brain
  • Constriction from the light reflex (In by II, out by III) is going to have to Cross over at the Pretectum/Posterior Commisure. If you cannot cross over there, then you are not going to be able to constrict both eyes when light is shined in there.

**** Known as “Prostitute Sign” because of Neuro-Syphilis

36
Q

Describe Holmes-Aide Pupil (Tonic Pupil)

A

Normal Accomodation BUT a SLOW reaction to light (Instead of NO reaction to light like ARGYLL ROBERTSON PUPIL)

Cause: Inflammation residual from INFECTIOUS process

37
Q

What are the two main arterial supplies for the eye?

A
  1. Internal Carotid Artery
  2. External Carotid Artery
  • *Ophthalmic Artery** (Off ICA)(***Rarely comes off of MIDDLE MENINGEAL artery)
  • Central Retinal Artery (inside the Optic Nerve)
  • Lacrimal Artery
  • Ethmoidal Artery (Anterior and Posterior)
  • Supraorbital Artery

Infraorbital Artery (Off Maxillary Artery)

Angular Artery (Off Facial Artery)

38
Q
A

B. Arterial Circle of the Iris

This is know as a Hyphema

39
Q

What causes Subconjunctival Hemorrhage?

A

Rupture of the Pericorneal Veins

40
Q
A

C. Central Retinal Vein Occlusion “Ketchup”

Central Artery Occlusion –> Red Cherry Spot

41
Q

Desribe the Venous Drainage of the Orbit.

A

Superior Opthalmic, Inferior Ophthalmic and Central Retinal Vein –> CAVERNOUS Sinus –> Internal Jugular Vein

42
Q

Describe the Dural Venous Drainage of the Skull.

A

If you get an infection in the Cavernous Sinus, it could lead all the way back to the brain!

Cavernous Sinus will drain the:

  • ORBIT
  • Upper Face
  • Dural Venous Sinuses

**** ONLY Anatomical space where an ARTERY (Cavernous Portion of ICA) travels through a venous structure!

43
Q

What are the structures that run within the Cavernous Sinus?

A
  • *Lateral Structures:**
    1. CN III
    2. CN IV
    3. CN V1
    4. CN V2 (ONLY Branch coming into the Cavernous Sinus that is NOT going through the Superior Orbital Fissure!)
  • *Medial Structures:**
    1. ICA (Cavernous Portion)
    2. CN VI
  • *Central Structures:**
    1. Pituitary Gland
  • *Superior Structures:**
    1. Optic Chiasm
44
Q

What are the clinical risks associated with the Cavernous Sinus?

A
  • Risk of Infectious Spread
  • Cavernous Sinus Thrombosis
  • Cavernous Sinus Syndrome –> Compression of Structures within the sinus (Opthalmoplesia)
45
Q
A

C. CN III, IV, VI and ICA

Neuroscience I (Exam 2) (11 decks)

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