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SF2 - Test 3 > 1 - Cranial Nerves > Flashcards

1 - Cranial Nerves Flashcards

1
Q

What Cranial Nerves exit the midbrain?

What Cranial Nerves exit the pons?

What Cranial Nerves exit the medulla?

What cranial Nerves exit the spinal cord?

A

Midbrain: III, IV

Pons: V, VI, VII, VIII

Medulla: IX, X, XII

Spinal Cord: XI

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2
Q

CN II exit from CNS? (important regions from table)

A

Thalamus, Hypothalamus

Pretectal Area, Superior Colliculus

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3
Q

What are the two exceptions to the rule that CN nuclei are the same level as the nerve entry/exit?

A

2/4 Trigeminal Nuclei

Spinal Trigeminal Nucleus extends caudally (to cervical spinal cord)

Mesencephalic Trigeminal Nucleus extends into midbrain

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4
Q

What is the general location of sensory vs motor of CN nuclei?

A

Sensory = Lateral

Motor = Medial

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5
Q

What is unique about CN II?

What is it formed by?

Where do they project to?

A

Only cranial nerve that is a CNS pathway, not a peripheral nerve

Formed by axons of retinal ganglion cells

- - -

Project to suprachiasmatic nucleus of hypothalamus, superior colliculi, and lateral geniculate nucleus of thalamus

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6
Q

What is the importance of the pretectal area?

A

Important for relay in pupillary light reflex pathway

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7
Q

Two Components and of CN III (Oculomotor)?

Nuclei?

A

Somatic Motor:

All extraocular muslces (ex. sup oblique/lat rectus), Levator palpebrae superior

Oculomotor Nucleus

- - -

Visceral Motor (via Ciliary Ganglion)

Parasympathetic innervaion of pupil constrictor and ciliary muscles

Edinger-Westphal Nucleus

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8
Q

Pupullary Reflex Pathway

Sensory Input?

Key Region?

Motor Output?

A

Sensory Input: CN II (light hits eye)

Key Region: Pretectal Area (between superior colliculus and thalamus)

Relays bilaterally to preganglionic parasympathetics neurons in Edinger-Westphal Nucleus; contralateral projection is through post. commissure (mediates consenual light response)

Motor Output: Edinger-Westphal Nucleus to ciliary ganglion to pupillary constrictor

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9
Q

Direct and Consensual Response: Oculomotor Lesion

A

Pupil will not constrict on side of lesion

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10
Q

Direct and Consensual Response: Horner’s Syndrome

A

Pupil can not dilate on impaired side

Other Symptoms: Ptosis, Anhydrosis

*Lesion of Sympathetics = Deficit in Dilation*

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11
Q

Direct and Consensual Response: Afferent Nerve defect

A

Sensory Loss

Impaired direct and consensual response on affected side.

Normal response on unaffected side.

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12
Q

Direct and Consensual Response: Benign Anisorcoria

A

Pupil Asymmetry; no clinical pathology

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13
Q

Clinical: Unilateral LMN Lesion of CN III

Common Causes?

A

Complete Loss of Function = “Down and Out” Eye

Ptosis = eyelid droop

Blown Pupil, no response to light (loss of parasympathetic constrictor)

Common Causes: Diabetes, tumors, compression of Posterior Communicating Artery, uncal herniation

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14
Q

What is unique about CN IV (Trochlear)

Main role?

A

Only CN to exit dorsal surface

Function: Innervates Superior Oblique (contralateral to nucleus) – Fibers will decussate

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15
Q

Clinical: Unilateral LMN Lesion of CN IV

Loss of Function?

Common Causes?

A

Loss of Function: Elevation and Extorion of affected eye–causes diplopia; clinical sign of Head Tilt

Common Causes: Head trauma (nerve vulnerable to shearing injury), tumor of midbrain/tectum, diabetes

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16
Q

Trigeminal Nerve (CN V) Components

A

Somatic Sensory:

Touch, pain, temperature, joint position, vibration

Face, mouth, anterior 2/3 of tongue (not taste), nasal sinuses, meninges (related to Migraines)

Branchial Motor: Muscles of mastication, tensor tympani, tensor veli palatini, mylohyoid, anterior digastric

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17
Q

Trigeminal Sensory Nuclei

Location

Input

Output

A

Location: Lateral mid-Pons

Input: large diameter sensory fibers from face; analogous to dorsal column; discriminative touch, vibration, proprioception

Output (Trigeminal Lemniscus): Second order neurons, crosses and joins medial lemniscus, projects to VPM of thalamus

18
Q

Trigeminal (CN V) Sensory Nuclei: Spinal Trigeminal Nucleus

Input

Output

A

Spinal Trigeminal Nucleus

Located laterally from mid-pons to upper cervical spinal cord, w/input from small diameter sensory fibers (crude touch, pain, temperature)

Spinal trigeminal tract carriers descending sensory fibers

Output (Trigeminothalamic tract): Second order neurons, joins anterolateral system

19
Q

Topographic Representation of Face

A

Face represented in “onion skin” pattern

Concentric rings centered around mouth

20
Q

Trigeminal Sensory Nuclei: Mesencephalic Trigeminal Nucleus

Location?

Input

Output

A

Location: Laterally from mid-pons to midbrain long lateral edge of periaqueductal grey

Input: Cell bodies of large diameter sensory fibers that convery priprioceptive sensation – “centrally located sensory ganglion”

Output: Descends to trigeminal motor nucleus, mediates jaw-jerk reflex

21
Q

Trigeminal Motor Nucleus

A

Contain LMN for branchiomotor functions of Trigeminal

Receives proprioceptive sensory input for jaw-jerk reflex (absent with UMN injury)

22
Q

Clinical: Trigeminal Neuralgia (tic douloureux)

A

Chronic pain condition

Type 1: Typical Form - extreme sporadic burning or shock-lik pain; may repeat in short intervals

Type 2: Atypical Form - constant aching, burning, or stabbing pain (lower intensity that Type 1)

Pain can be incapacitating

Cause: May be from nerve compression/inflammation

23
Q

Clinical: Trigeminal Disorders - Shingles

A

Cause: Herpes Zoster (chicken pox virus), virus reemerges (usually older adults), as shingles rash

Postherpetic Neuralgia: Severe pain in area which has shingles rash

Vision loss possible if eye affected

Vaccine available (rec’d for adults 50+)

24
Q

Clinical: Trigeminal Disordrs - Sensory Loss

A

Peripheral lesion

CNS Lesion in Lateral Pons, Medulla

If Spinothalamic fibers in the anterolateral system are also injured – ipsilateral sensory loss in face, contralateral sensory loss in body

25
Q

CN VI (Abducens)

Type

A

Type: Somatic Motor - lateral rectus (abduction of eye)

26
Q

Clinical: Unilateral LMN Lesion of CN VI (Abducens)

A

Lateral gaze paralysis

Inability to abduct affected eye

At Rest: Medial Strabismus (cross eye), horizontal diplopia

27
Q

CN VII (Facial)

Types? (4)

A

Branchiomotor: Muscles of face, stapedius, post. digastric, stylohyoid muscles–Facial Expression

Parasympathetics: Sublingual, Submandibular, Lacrimal

Visceral (Chem) Sensory: Ant. 2/3 tongue Taste

Somatic Sensory: Portion of outer ear

28
Q

CN VII (Facial) Nuclei (4x)

A

Facial Nucleus: LMN innervating muscles of face (branchiomotor)

Superior Salivatory Nucleus: Salivary and Lacrimal glands (parasympathetics)

Spinal Trigeminal Nucleus: Somatic sensation from outer ear

Solitary Nucleus: Visceral (chemical) sensation from ant. 2/3 tongue

29
Q

Corneal Reflex

Afferent Limb

Efferent Limb

A

Afferent Limb: Trigeminal Nerve (ophthalmic division), Chief Sensory/Spinal Trigeminal Nuclei

Note: Blink can be invoked by visual stimuli–input is CN II in this case

Efferent Limb: Facial Nucleus and Nerve, Orbicularis Oculi Muscles

30
Q

Clinical: Unilateral LMN Lesion of CN VII

A

Ipsilateral Face Weakness from UMN lesion

- - -

Bell’s Palsy (most common)

Ipsilateral weakness, loss of taste sensation from ant. ipsilateral tongue

Hyperacusis, ear pain

Drooling

Dry eyes, mouth

“Crocodile Tears” due to recovery of paraysmpathetics

“Synkinesis”, or abnormal movements of face

31
Q

CN VIII (Vestibulocochlear)

Type?

A

Somatic Sensory

32
Q

CN IX (Glossopharyngeal)

Components (4x)

A

Branchiomotor: Stylopharyngeus

Parasympathetics: Parotic Gland

Somatic Sensory: Touch, pain, temperature from posterior 1/3 of tongue, pharynx, middle ear, portion of outer ear

Visceral Sensory: Baro- and chemo-receptors in carotid body, taste receptors in posterior 1/3 of tongue

33
Q

CN IX (Glossopharyngeal) - Nuclei

A

Branchiomotor: LMNs in Nucleus Ambiguus

Parasympathetic: Preganglionic neurons in inferior salivatory nucleus

Somatic Sensory: Spinal trigeminal nucleus

Visceral Sensory:

Baro- and chemo-receptors: Caudal solitary nucleus

Taste Receptors: Rostral solitary nucleus

34
Q

CN X (Vagus) - Types

A

Branchiomotor: Muscles of pharync and larynx (speech and swallowing)

Parasympathetic: Major portion of nerve, heart, lungs, digestive tract

Somatic Sensory: Pharynx, larynx, meninges, portion or outer ear

Visceral Sensory: Baro-and chemo-receptors in aortic arch, cardiorespiratory and digestive systems; taste receptors in epiglottis, posteriorpharynx

35
Q

CN X (Vagus) - Nuclei

A

Branchiomotor: LMNs in nucleus ambiguss

Parasympathetic: Preganglionic neurons in dorsal motor nucelus of vagus

Somatic Sensory: Spinal trigeminal nucleus

Visceral Sensory:

Baro-and chemo-receptors: Causal solitary nucleus

Taste receptors: Rostral solitary nucleus

36
Q

Clinical: Unilateral lesion of Nucleus Ambiguus

A

Ipsilateral paralysis of the soft palate, pharynx, and larynx

Uvula will deviate away from lesion

Symptoms: Dusphonia (difficulty speaking), Dyspnea (difficulty breathing), Dysphagia (difficulty swallowing)

Gag reflex diminished/absent ipsilaterally; afferent in CN IX, efferenct from nucleus ambiguss

37
Q

CN XI (Accessory) - Type

A

Branchiomotor: Trapezius, Sternocleidomastoid

38
Q

Clinical: Unilateral LMN Lesion of CN XI

A

Paresis/Paralysis of the ipsilateral sternocleidomastoid and ipsilateral trapezius

Patient unable to turn their head away from side of lesion

Ipsilateral shoulder drop, may have difficulty raising ipsilateral arm above horizontal

39
Q

CN XII (Hypoglossal) - Type

A

Somatic Motor: Intrinsic and extrinsic muscles of tongue (except palatoglossus)

40
Q

Clinical: Unilateral LMN Lesion of CN XII

A

Ipsilateral tongue weakness–tongue deviates TOWARD lesion

Ipsilateral fasciculations, Atrophy

41
Q
A

SF2 - Test 3 (25 decks)

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