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Y1 - Neuroanatomy - Exam 2 > 5. Eye Movement > Flashcards

5. Eye Movement Flashcards

(44 cards)

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1
Q

three categories of eye movements:

A
  1. conjugate: eyes move in SAME direction
  2. vergence: focus shifts between near and far objects
  3. vestibulo-ocular: keeps target fixed on retina during head movements
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2
Q

two types of conjugate eye movement

(eyes move in same direction)

A
  1. saccadic: rapid movement; vision moves from target to target
  2. smooth pursuit: maintains image of moving target fixed on the retina
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3
Q

two types of vergence eye movements:

eyes moving in opposite directions

A
  • convergence: visual axis of eyes CONVERGE (near focus)
  • divergence: visual axis of eyes DIVERGE (far focus)
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4
Q

describe the eye movements when looking at a painting

(free examination)

A

saccadic eye movements;

  • tracing the attention given to the piece of art;
  • extra attention given to identifying the faces
  • more time spent on primary subjects
  • also may depend on what you ask the patient to look at
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5
Q

describe the eye movements when looking at a painting

(give the ages of people)

A
  • saccadic eye movements
  • Spending more time looking for visual cues of ages; looking at peoples’ faces
    • Still includes fast, saccadic movements
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6
Q

list the type/# of extraocular muscles

A
  • 4 recti muscles
  • 2 oblique muscles
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7
Q

which cranial nerves innervate the extraocular muscles?

A
  • CN III: oculomotor
  • CN IV: trochlear
  • CN VI: abducens
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8
Q

oculomotor nerve (CN III)

innervates which extraocular muscles?

A
  • superior RECTUS
  • inferior RECTUS
  • medial RECTUS
  • inferior OBLIQUE
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9
Q

trochlear nerve (CN IV)

innervates which extraocular muscle(s)?

A

superior oblique muscle

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10
Q

abducens nerve (CN VI)

innervates which extraocular muscle(s)?

A

LATERAL rectus muscle

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11
Q

muscle for:

elevation and upgaze

A

superior rectus

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12
Q

muscle for:

ADDUCTION of th eye; pulls nasal/medial direction

A

medial rectus

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13
Q

muscle for:

depression, downgaze

A

inferior rectus muscle

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14
Q

muscle for:

ABduction of the eye; lateral gaze/or temporal gaze

A

abducens nerve

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15
Q

brainstem gaze centers:

to gaze towards RIGHT

A
  1. Left frontal eye cortex –>
  2. left medial longitudinal faciculus –>
  3. right abducens nucleus:
    • innervates right abducens nerve –> R lateral rectus mm.
    • innervates left oculomotor nerve–> L medial rectus mm.
  4. Overall fxn: shifts gaze to right
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16
Q

what are the brainstem gaze centers,

and where are they located?

A
  1. horizontal gaze center – PONS (think: bridge)
  2. vertical gaze center – MIDBRAIN (think: “V”)
  3. vergence gaze center – MIDBRAIN (think: “micky mouse sign”)
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17
Q

brainstem gaze centers:

define

A

collections of neurons serving extraocular muscles

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18
Q

what is/where is the horizontal gaze center?

Study These Flashcards
A
  • paramedian pontine reticular formation, also known as PPRF or paraabducens nucleus
  • found in the pons
19
Q

fxn and how does the PPRF

(paramedian pontine reticular formation) work?

Study These Flashcards
A
  • involved in the coordination of eye movements, particularly horizontal gaze and saccades
  • flow of information:
    1. frontal eye fields: plays an important role in the control of visual attention and eye movements
    2. PPRF
      • medial longitudinal fasciculus (MLF) –> oculomotor nerve –> Left medial rectus
      • abducens nerve –> Right lateral rectus
20
Q

CC: MLF (medial longitudinal fascicululs)

syndrome

Study These Flashcards
A

aka: internuclear ophthalmoplegia

impacting internuclear pathway, and innervation from cortex –> abducens is still in tact, but communication between 2 cranial nerve nuclei is what is interrupted;

common in demyelinated diseases, such as multiple sclerosis

21
Q

where is the vertical gaze center located?

where do fibers cross?

Study These Flashcards
A
  • located in rostral midbrain
  • fibers cross at posterior commissure, w/ pineal gland in close proximity
22
Q

where does vertical gaze center project to?

what is its function?

Study These Flashcards
A
  • projects to oculomotor subnuclei
  • projects to muscles that do vertical motion: superior and inferior recti muscles
23
Q

where is the vergence gaze center located?

where does it project to?

Study These Flashcards
A
  • located in rostral midbrain (reticular formation)
  • projects to:
    • CN III (convergence)
    • CN VI (divergence)
24
Q

which cranial nerve is associated w/ CONVERGENCE?

Study These Flashcards
A

CN III

(oculomotor)

25
which cranial nerve is associated w/ DIVERGENCE?
CN IV trochlear
26
what are the **cortical gaze centers**?
* FEF: frontal eye field * PEF: parietal * OEF: occipital * TEF: temporal
27
**frontal eye field:** fxn and projection
* fxn: origin of **saccadic eye** movements * project to **vertical and horizontal gaze centers & to superior colliculus**
28
what does **parietal eye field** influence?
influence saccadic movements
29
what does **temporal eye field influence?**
influences smooth pursuit
30
**occipital eye fields:** fxn, and action
* the origin of **vergence movements** * focus shifts: faraway object \<--\> near target * signal to oculomotor or abducens nuclei
31
CC: strabismus
(eyes are not aligned) / aka Cranial Nerve VI palsy Lateral rectus is NOT working, so the medial rectus is pulling inwards
32
CC: Patient is cross-eyed and has trouble navigating stairs
vestibular testing indicates the patient has strabismus; this is CN VI palsy (one eye looks directly at the object you are viewing, while the other eye is misaligned inward (esotropia, "crossed eyes" or "cross-eyed"), outward (exotropia or "wall-eyed"), upward (hypertropia) or downward (hypotropia).
33
how would you describe the location of the misaligned globe? which muscle/cranial nerve is affected?
The LEFT eye is **elevated and ADDUCTED** the **superior oblique** muscle is affected; CN IV (**trochlear** nerve)
34
what is the normal movement for the **superior oblique** muscle?
"down and out" by the tochlear nerve
35
cranial nerve IV supplies which superior oblique? which tendon is associated?
it is the TROCHLEAR nerve; CN IV tendon of **superior oblique**
36
actions of **superior oblique?**
primary action is **intorsion (medial rotation);** secondary is **ABduction and DEPRESSION** (inward and downward)
37
innervation and action of the **inferior oblique muscle**?
cranial nerve (III): oculomotor nerve ## Footnote **extorsion, elevation, ABduction**
38
trochlea: define
fascial sling in upper corner of the eye; supports the superior trochlear muscle
39
name the axes of the **globes** (eyeball) in the **orbits** (eyesockets)?
Red axis paralell to nose bridge - Axis of eyeball Blue axis obliquely - Axis of orbit
40
**extraocular eye** muscles and **innervation**
LR6 - SO4 - AO3 * **Lateral rectus: CN 6 (abducens)** * **Superior oblique: CN 4 (trochlear)** * **ALL OTHERS: CN 3 (oculomotor)** * superior rectus * inferior rectus * medial rectus * inferior oblique
41
primary actions of the extraocular muscles
* Lateral rectus: **ABDUCTION** * Medial rectus: **ADduction** * Superior rectus: **Elevation** * Interior rectus: **Depression** * Superior oblique: **Intorsion** * Inferior oblique: **Extorsion**
42
How to test the CN IV:
use the superior oblique to depress an ADDUCTED globe; if patient is looking down to test superior oblique is working --\> put the eye in an ADDucted position (and then see if it depresses the eye)
43
what is the purpose of the extra-ocular muscles?
to allow the eyes to remain fixed on an object even when turning the head side to side (i.e. ear to shoulder)
44
which cranial nerve palsy would result in a compensatory head tilt?
cranial nerve IV palsy --\> if the right eye is extorted and sl elevated causing double vision --\> to compensate the pt tilts head to the opposite side

Y1 - Neuroanatomy - Exam 2 (12 decks)

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