Lecture 14: Movement of the eyes

Question 1

What nerves are required to close your eye

Answer 1

CN 7 (striated muscle)

Question 2

What nerves are needed to open your eye?

Answer 2

CN 3 and sympathetics (striated and smooth muscle)

Question 3

What nerves are needed to move your eye?

Answer 3

CN 3,4,6 (striated muscle)

Question 4

What nerves are required to lubricate your eye?

Answer 4

parasympathetic via CN 7 (lacrimal gland)

Question 5

What nerves are needed to focus and control light into the eye?

Answer 5

parasympathetics via CN 3 and sympathetics (smooth muscle)

Question 6

What muscle to you use to close your eye?

Answer 6

obicularis oculi (via CN7)

Question 7

What muscles do you use to open your eye?

Answer 7

one muscle attaches to the upper eyelid (CN 3) and smooth muscle that attaches to the eyelid, superior tarsal muscle, via sympathetic innervation (cervical ganglion of the sympathetic chain)

Question 8

Describe the muscles that attach to a common tendon that help to move the eye.

Answer 8

rectus muscles (superior, medial, lateral and inferior)

Question 9

Describe the two muscles that help to move the eye outside of the common tendon?

Answer 9

superior oblique and inferior oblique (lavator palpebrae moves the eyelid)

Question 10

How do the superior and inferior muscles cause adduction and abduction help to move the eyeball left or right?

Answer 10

the majority of the attachment of muscles at top and bottom of the eye are medial to the vertical axis which can help to pull the eye around the vertical axis

Question 11

How do the eyes rotate medially or laterally?

Answer 11

the bottom 2 muscles (inferior rectus and inferior oblique) laterally rotate the bottom of the eye and the top 2 muscles (superior rectus and superior oblique) medially rotate the top of the eye

Question 12

What is important in trying to test individual eye muscles, ie. specifically superior rectus and inferior oblique.

Answer 12

both the superior and the inferior oblique can elevate the eye so you must have the patient put one of the muscles parallel to the movement that you are testing (to test the IO, you must adduct the eye then look down; testing the SO adduct the eye then look up)

Question 13

If a patient came to you with their head tilted to the right and their head flexed, what muscle would you suspect is affected?

Answer 13

lesion on the left superior oblique, (head is tilted away from the paralyzed left superior oblique); tilted head head helps to reduce the diplopia because it aligns with the eye under volitional control = trochlear (CN IV)

Question 14

If a patient came to you with the head rotated to either side, what nerve would you be concerned is affected?

Answer 14

head will rotate toward the paralyzed side, the lesion affects the lateral rectus which is controlled by the abducens nerve (CN VI)

Question 15

What would you expect of a patient that has a lesion on the CN III (oculomotor)?

Answer 15

patient will be “down and out” and their eyelid will droop

Question 16

What is the nemonic for eye position after nerve damage?

Answer 16

LR6 (in) SO4 (up and lat rotation) Other 3 (down and out)

Question 17

Describe the how the abducens coordinates the movement of both eyes.

Answer 17

input form the frontal eye field synapses on the contralateral paramedical pontine reticular formation (PPRF) which sends input to the abducens nucleus which in turn controls the ipsilateral lateral rectus and the contra lateral medial rectus via the MLF and oculomotor nucleus/nerve

Question 18

Describe the nerves that assist in lubricating your eye.

Answer 18

superior salivatory/lacriminal nucleus sense fibers out with CN VII that innervate the lacrimal gland after synapsing not he ptyerogoid/palatine nucleus

Question 19

Describe how parasympathetics control the focusing of the lens.

Answer 19

ciliary muscles that are attached to the lens can change its shape via suspensory ligaments; ciliary muscles are innervated by fibers from the edinger westphal N. which sends parasympathetics out via the oculomotor nerve.

Question 20

What controls the light coming into the eye?

Answer 20

dilator and constrictor smooth m. in the iris change the iris diameter; constrictor muscles are innervated by parasympathetics from edinger westphal nucleus and dilator s are innervated by superior sympathetic ganglion cells

Question 21

What is meant by the “consensual response” of the pupillary constriction?

Answer 21

pupils will respond to direct stimulation from light but that stimulus also synapse on the pretuctum nucleus which go to the synapse of westphal and elicit a response from the opposite side

Question 22

What is special about the innervation to the cornea?

Answer 22

it is a structure that is very heavily innervated, sensory to the eye (touch, pain and temp) is carried by the ophthalmic branch of the trigeminal n. and since this functions as the DRG of the head, it can also be affected by a shingles like out break (herpes zoster ophthalmicus)