Eye Movements

Question 1

What are the 3 planes and corresponding axes of rotation of extraocular muscles?

Answer 1

-horizontal = vertical
-vertical = horizontal
-torsional = visual

Question 2

what does Sherrington’s law of reciprocal innervation state?

Answer 2

For each eye, ‘antagonist’ muscles receive equal but opposite innervation

Question 3

what does herring’s law of motor correspondence state?

Answer 3

For conjugate movements, ‘synergist’ muscles receive equal innervation (from CNS), i.e. certain muscles must co-contract (or co-relax) = “yoked” pairs Oculomotor Coordination

Question 4

name the ipsilateral antagonists

Answer 4

-medial rectus
-lateral rectus
-superior rectus
-inferior rectus
-superior oblique
-inferior oblique

Question 5

for each of the RE extraocular muscles name the contralateral synergists so state the yoked muscle pairs of the two eyes

Answer 5

-medial rectus = lateral rectus
-lateral rectus = medial rectus
-superior rectus = inferior oblique
-inferior rectus = superior oblique
-superior oblique = inferior rectus
-inferior oblique = superior rectus

Question 6

why are there two sub divisions of the medial rectus?

Answer 6

because it is involved in both horizontal alignment and vergence