Anatomy - Eyes & Ears Flashcards by Jerrica Park

Name CN II, III, IV, V, V1, and VII

II = Optic
III = Oculomotor
IV = Trochlear 
V = Trigeminal
V1 = Ophthalmic
VII = Facial

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Innervation, origin, and insertion of superior rectus?

Innervation = CN III

Origin = Sclera, superior aspect of globe

Insertion = Annulus tendineus

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Innervation, origin, and insertion of medial rectus?

Innervation = CN III

Origin = Sclera, medial aspect of globe

Insertion = Annulus tendineus

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Innervation, origin, and insertion of lateral rectus?

Innervation = CN VI!! Abducens n!

Origin = Sclera, lateral aspect of globe

Insertion = Annulus tendineus

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Innervation, origin, and insertion of inferior rectus?

Innervation = CN III

Origin = Sclera, inferior aspect of globe

Insertion = Annulus tendineus

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Innervation, origin, and insertion of superior oblique?

Innervation = CN IV!! Trochlear n!

Origin = Sclera, superior aspect of globe (after passing through trochlea)

Insertion = Annulus tendineus

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Innervation, origin, and insertion of inferior oblique?

Innervation = CN III

Origin = Sclera, top of globe

Insertion = Maxilla!!

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What is the only external eye muscle that does NOT originate at the annulus tendineous?

Inferior oblique

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What muscle is innervated by the trochlear nerve?

Superior oblique

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What muscle is innervated by the abducens nerve?

Lateral rectus

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What innervates the muscle of the upper eyelid?

CN III: innervates levator palpebrae superiorus

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What provides autonomic innervation to allow for pupil constriction and accommodation?

CN III: innervation to constrictor pupillae (constriction) and ciliary muscles (accommodation)

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What nerve provides somatic sensation of the cornea and sclera?

CN V1 (ophthalmic nerve)

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What innervation does V2 provide in the orbit?

None, it just passes through

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What is the action of the lateral rectus muscle?

Abduction of gaze

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What is the action of the superior oblique muscle?

Depression and medial rotation

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What is the action of the superior rectus muscle?

Elevation and medial rotation

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What is the action of the inferior rectus muscle?

Depression and lateral rotation

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What is the action of the medial rectus muscle?

Adduction of gaze

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What is the action of the inferior oblique muscle?

Elevation and lateral rotation

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What muscles are used to elevate the gaze?

Superior rectus (elevation and medial gaze) + inferior oblique (elevation and lateral gaze)

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What muscles are used to depress the gaze?

Inferior rectus (depression and lateral rotation) + superior oblique (depression and medial rotation)

What is the starting position to test the lateral rectus?

Resting position

What is the starting position to test the medial rectus?

Resting position

What is the starting position to test the superior rectus muscle?

Elevate from abduction

What is the starting position to test inferior rectus muscle?

Depress from abduction

What is the starting position to test the superior oblique muscles?

Depress from adduction

What is the starting position to test the inferior oblique muscles?

Elevate from adduction

In general, what should the starting position be to test the OBLIQUE external eye muscles?

Adduction

In general, what should the starting position be to test the RECTUS external eye muscles?

Resting for medial/lateral | Abduction for superior/inferior

Name the nerve deficit, muscle deficit, and compensatory behavior seen in a patient with a gaze that is stuck in the lateral, downward position.

This is a lateral strabismus (+ downward gaze) Caused by CN III lesion Muscle affected = Superior, inferior, and medial rectus, + inferior oblique (Downward gaze is due to lack of opposition to intact superior oblique muscle) Patient may turn head to affected side.

Name the nerve deficit, muscle deficit, and compensatory behavior seen in a patient with a gaze that is stuck in the medial position.

This is a medial strabismus Caused by CN VI lesion Muscle affected = lateral rectus Patient may turn head to the affected side

Name the nerve deficit, muscle deficit, and compensatory behavior seen in a whose vision blurs when looking downwards (ex: reading or walking down stairs).

Caused by CN IV lesion Muscle affected = superior oblique; rotational ability of the inferior rectus is unopposed Patient may tilt head to the unaffected side

Your patient has advanced syphilis. His pupils constrict when you bring an object near his face, but not when shining your pen light near his eyes. What is the name for this phenomenon?

Argyll-Robertson response - damage to the autonomic nerves to the eyes

What is the initial symptom of a cavernous sinus thrombosis, and why does it occur? What can be seen after the initial symptom?

Initial symptom: medial strabismus. Occurs because the abducens nerve travels unprotected through the cavernous sinus. Increased pressure --> deficit of lateral rectus --> medial strabismus. After the initial symptoms, as additional nerves are compressed, you can see: - Paralysis of all extrinsic eye muscles (involvement of CN III and VI, which are more protected than VI) - Fixation of the pupil (PNS and SNS involvement) - Edema of eyelid/pulsing exophthalmos (excess ECF - normally drains into sinus; pulsing from internal carotid) - Paresthesia of the forehead (compression of V1) - Horner syndrome (loss of SNS to V1 dermatome)

Describe Horner Syndrome and a possible associated condition

Horner syndrome: - Contraction of pupil (dilator pupillae is paralyzed) - Ptosis (smooth muscle of upper eyelid is paralyzed) - Loss of sweating (interrupted V1 SNS communication with sweat glands) - Flushing (No vasoconstriction via SNS in V1, so dilation occurs) *Can be associated with cavernous sinus thrombosis

What structures pass through the annulus tendineous?

CN II | Blood supply to the orbit: ophthalmic artery, housed in within meningeal coating

What bone forms the ceiling of the orbit?

Frontal

What bone forms the floor of the orbit?

Maxilla

What bone comprises most of the medial wall of the orbit?

Orbital plate of the ethmoid bone

What bone comprises the medial aspect of the posterior wall of the orbit?

Lesser wing of the sphenoid

Through what bone does CN II travel?

Lesser wing of the sphenoid

What bone comprises the lateral aspect of the posterior wall of the orbit?

Greater wing of the sphenoid

Through what bony landmark do all nerves (except CN II) run through on their way to the orbit?

Superior orbital fissure

What part of the ear is involved in conductive hearing loss?

Middle ear: TM and ossicles

What structure(s) are involved in sensorineural hearing loss?

Inner ear/CN III

Name the ossicles of the ear in order from most external to internal

Malleus, incus, stapes

With what structures does the stapes interact?

The incus on the lateral side, the oval window medially

What is a normal finding for the Weber test?

Equal volume perceived in both ears

During a Weber test, your patient tells you that they hear your tuning fork more loudly on the right side. What does this indicate?

Either: 1. ) conductive hearing loss on the right 2. ) sensorineural hearing loss on the left

What is a normal finding for the Rinne test?

Air conduction > bone Patient should hear the tuning fork more loudly when it is outside of the external auditory canal than when it is placed on the mastoid process.

During a Rinne test, your patient tells you that they hear your tuning fork more loudly when it is placed near their ear, outside of the external auditory canal. What does this indicate?

This is a normal finding for the Rinne test.

During a Rinne test, your patient tells you that they hear your tuning fork more loudly when it is placed on their mastoid process. What does this indicate?

This suggests a possible conductive hearing loss problem.