Eye Nerves DLA

Question 1

What are the functions of the oculomotor nerve?

Answer 1

-Motor component to majority of extraocular muscles
– muscles that move the eye

• Parasympathetic component to ciliary and pupillary
constrictor muscles of the eye
– controls the shape of the lens and narrows the diameter of the pupil

• Passes through superior orbital fissure

• Passes into the interpeduncular fossa where it attaches to
the brainstem
– between the posterior cerebral and superior cerebellar artery

• Nucleiarelocatedinthemidbrain – motor: oculomotor
– parasympathetic: Edinger-Westpha

Question 2

What is the function of the trochlear nerve?

Answer 2

Motor to one extraocular muscle (superior oblique)
• Passes through the superior orbital fissure

• Attaches to the brainstem dorsally just inferior to the inferior colliculus
• Nucleus is located in the midbrain

• It is a thin nerve that travels a relatively
long distance

• In its course it briefly travels along the superior cerebellar artery

Question 3

What is the function and path of Abducens nerve?

Answer 3

• Motor to one extraocular muscle (lateral rectus)
• Nucleus located in the pons
• Attaches to the brainstem ventrally at the pontomedullary junction
• Passes through the superior orbital fissure

Question 4

Explain the. testing for CN III, IV, VI

Answer 4

• The muscles of the eyes work together to move our eyes together as a unit

• The most common complaint from paralysis to any one of these muscles is diplopia
– commonly when trying to look in the direction of the muscle action

• Many of the muscles perform similar actions

• When we test the integrity of the nerves and muscles we test them
together – H-test

• The H-test is performed to isolate the different muscles and test them individually. This is not necessarily the same as the actions they perform
• Eye movements can be affected by either nerve damage (common) or impingement of the muscle after skeletal trauma

Question 5

What are the components if the pupillary light reflex?

Answer 5

Two component pathway

– CN II (afferent limb): sensory
– CN III (efferent limb): parasympathetic component

Question 6

explain the components of the accomodation reflex

Answer 6

• Fornearvision
– attempt to focus on near object

• CNII(afferentlimb)
• CNIII(efferentlimb)
– parasympathetic component
– pupil constricts via pupillary constrictor muscle (sphincter pupillae)
– lens “fattens up” via constriction of ciliary muscles for increased refraction