Neurology of the visual system

Question 1

Version

Answer 1

Simultaneous eye movement of both eyes in same direction

Question 2

Duction

Answer 2

Eye movement in one eye

Question 3

Vergence

Answer 3

Simultaneous eye movement of both eyes in opposite directions

Question 4

Convergence

Answer 4

Simultaneous adduction (inward) eye movement in both eyes when viewing a near object

Question 5

6 extraocular eye muscles

Answer 5

• Superior rectus
• Inferior rectus
• Lateral rectus
• Medial rectus
• Superior oblique
• Inferior oblique

Question 6

Superior rectus

Answer 6

• 12 o’clock attachment to eye

- moves eye up

Question 7

Inferior rectus

Answer 7

• 6 o’clock attachment to eye

- moves eye down

Question 8

Lateral rectus

Answer 8

• attachment on the temporal side of the eye
• moves eye towards outside of the head (towards the temple and away from the midline)
• ‘external rectus’

Question 9

Medial rectus

Answer 9

• attachment on the nasal side of eye
• moves eye towards middle of the head (towards the nose/medially)
• ‘internal rectus’

Question 10

Superior oblique

Answer 10

• attachment high on temporal side of eye
• moves eye down and in (clinical observation)->diagonal pattern
• passes under superior rectus
• travels through trochlea

Question 11

Inferior oblique

Answer 11

• attachment low on nasal side of eye
• passes over inferior rectus
• moves eye up and out->diagonal

Question 12

Innervation of extraocular muscles (third cranial nerve)

Answer 12

Superior branch

• superior rectus (elevates eye)
• lid levator (raises eyelid)

Inferior branch

• inferior rectus (depresses eye)
• medial rectus (adducts eye)
• inferior oblique (elevates eye)
• parasympathetic nerve (constricts pupil)

Question 13

Innervation of extraocular muscles (fourth cranial nerve)

Answer 13

Superior oblique (depresses eye)

Question 14

Innervation of extraocular muscles (sixth cranial nerve)

Answer 14

Lateral rectus (abducts eye)

Question 15

Elevation

Answer 15

Up

• supraduction->one eye
• supraversion->both eyes

Question 16

Depression

Answer 16

Down

• infraduction->one eye
• infraversion->both eyes

Question 17

Dextroversion

Answer 17

Movement of both eyes right

• right abduction
• left adduction

Question 18

Levoversion

Answer 18

Movement of both eyes left

• right adduction
• left abduction

Question 19

Torsion

Answer 19

Rotation of eye around anterior-posterior axis of eye

Question 20

Sixth nerve palsy

Answer 20

• cranial nerve VI (abducens nerve) dysfunction
• affected eye unable to abduct and deviates inwards
• double vision worsens on gazing to affected eye side

Question 21

Third nerve palsy

Answer 21

• affected eye down and out
• observable droopy eyelid
• muscles not innervated by cranial nerve III are the only ones functioning
• unopposed superior oblique innervated by cranial nerve IV (down)
• unopposed lateral rectus action innervated by cranial nerve VI

Question 22

Extraocular Muscle Testing

Answer 22

• Isolate muscle to be tested by maximising action and minimising other muscle action
• abduction (lateral rectus)
• adduction (medial rectus)
• elevated and abducted (superior rectus)
• depressed and abducted (inferior rectus)
• elevated and adducted (inferior oblique)
• depressed and adducted (superior oblique)