Pathway for Horizontal Gaze

Question 1

from the paramedic pontine reticular formation (PPRF)→ Synapses on motor nucleus in ipsilateral abducens nucleus → _____

leads to what movement?

Answer 1

contraction of:
IPSILATERAL
Lateral rectus

Question 2

from the paramedic pontine reticular formation (PPRF) → Synapses on internuclear neuron in ipsilateral abducens nucleus → _____

leads to what movement?

Answer 2

contraction of the:
CONTRALATERAL
Medial Rectus

from synapse of internuclear neuron in ipsilateral abducens n → medial longitudinal fasiculus → **SYNAPSE: contralateral occulomotor neuron → contraction of contralateral MR

Question 3

from the paramedic pontine reticular formation (PPRF) → Synapses on inhibitory neuron in medullary reticular formation (MRF) → ____ AND ____ (two different pathways)

Answer 3

BOTH synapse on the contralateral abducens n

1) motor neuron for contralateral abducens nerve → inhibit contraction of contralateral lateral rectus
2) internuclear neuron → passes inhibitory signal through MLF back to synapse on ipsilateral oculomotor nucleus motor neuron → inhibit contraction of ipsilateral medial rectus.

Question 4

vestibulo-ocular reflex: what is a normal sign?

Answer 4

If the eyes turn against the direction the head is turned

(i.e.: Head turned to right → activation of vestibular system → CN VIII → vestibular nucleus → paramedian pontine reticular formation (PPRF) → both eyes drift left)

Question 5

Slow voluntary movement that requires visual target?

Answer 5

Pursuit

Question 6

Fast voluntary movement that does NOT require a visual target

Answer 6

Saccades