CN Course and Distribution Flashcards

1
Q

III

A

Oculomotor

  1. Anterior midbrain
  2. Middle cranial fossa
  3. Lateral wall of cavernous sinus
  4. Divides into superior (LPS and SR) and inferior (MR, IR, IO)
  5. Passes through superior orbital fissure
  6. Eye muscles
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2
Q

Which oculomotor branch has somatic motor and parasympathetic nerves passing through?

A

Inferior

Superior

  • GSE - LPS and SR

Inferior

  • GSE - MR, IR,IO
  • GVE - ciliary and sphincter pupillae
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3
Q

How does parasympathetic innervation of III get to its destination?

A

Hitch hikes on short ciliary nerves (of V1)

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4
Q

Sympathetic innervation of intrinsic eye muscles

A

Pre-gang neurons to superior cerivical ganglia

Post-gang neurons to long and short ciliary nn.

  • Wrap around IC artery
  • IC plexus

Innervates

  • Dilator pupillae
  • Ciliary mm.
  • Superior tarsal m.
    • SM
    • Attached to LPS and lid
    • Opens lid up ALL THE WAY
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5
Q

CN III lesions

A

Diplopia

Lateral strabismus

Mydriasis

Dry eye

Ptosis

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6
Q

VII

A
  1. Two roots from pons near PMJ
  2. Laterally in posterior cranial fossa with vestibulocochlear n.
  3. Enter IAM
  4. Pass through facial canal, branch into GP and CT
  5. Remaining VII is facial n. proper and continues down through stylomastoid foramen
  6. Posterior auricular n., Posterior digastric n., Stylomastoid branch off
  7. Pass THROUGH parotid to form plexus
    1. TZBMC
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7
Q

CN IX lesions

A

Supranuclear (in brain) = contralateral paralysis

  • Tongue goes to side opposite of injury

Peripheral (after leaving brainstem) = ipsilateral paralsys

  • Tongue goes to same side of injury/lesion
  • “Lick your wounds”
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8
Q

Parasympathetic innervation of lacrimal gland

A

Pre-gang

  • Super sal nuc.
  • GP of VII
  • Joins with DP (symp) = vidian n.

Post-gang

  • Pterygopalatine gang
  • Hitch hikes on zygomatic n. of V1
  • Hitch hikes on lacrimal gland of V2 to innervate lac gland (what actually stimulates tears) via lac n. of V1
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9
Q

Parasympathetic: chorda tympani

A

Joins V3 on the way to sublingual and submandibular glands

Goes through submandibular ganglion

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10
Q

Posterior auricular n. innervates what muscle?

A

Auricularis posterior and occipitalis

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11
Q

Temporal n. innverates what muscle?

A

Motor - auricularis anterior/superior, frontalis, orbicularis oculi, corrugator supercilii, procerus

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12
Q

Zygomatic (malar) n. innverates what muscle?

A

Motor - orbicularis oculi and zygomaticus

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13
Q

Buccal (infraorbital) n. innervatess what muscle?

A

Motor - buccinator, orbicularis oris

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14
Q

Mandibular (maginal) n. innervates what muscle?

A

Motor - depressor labii inferioris, depressor anguli oris, mentalis

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15
Q

Cervical n. innervates what muscle?

A

Motor - depressor anguli oris and platysma

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16
Q

CN VII lesions

A

Bell’s Palsy - unilateral face paralysis from damage to SVE of VII

Temporary from dental procedures

  • Inferior alveolar nerve block into parotid bed
  • Improves when anesthetic wears off

Affected at stylomastoid foramen

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17
Q

CN IX

A
  1. Anterior medulla
  2. Passes laterally in posterior cranial fossa
  3. Jugular foramen
  4. Descends through upper part of neck to back of tongue
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18
Q

Tympanic n.

A

Branch of IX

  • Enters middle ear cavity
  • Sensory and pre-gang para fibers
  • Forms part of tympanic plexus
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19
Q

Tympanic plexus

A

IX br

Sensory and sympa to middle ear cavity, pharyngotympanic tube, mastoid air cells

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20
Q

Lesser petrosal

A

IX br

  • Travels through foramen ovale
  • Fibers synapse in otic gang
  • Travel to parotid
    • Hitch hiking on V3, auriculotemporal n.
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21
Q

Parasympathetic innervation of parotid

A

Pre-gang neuron

  • Inferior sal. nuc
  • IX exits jugular foramen
  • Tympanic n. of IX joins tympanic plexus = lesser petrosal n.
  • Lesser petrosal exits foramen ovale

Post-gang neuron

  • Otic gang
  • Hitch hikes on auriculotemporal n. of V3
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22
Q

X

A
  1. Anterior medulla
  2. Laterally pass through posterior cranial fossa
  3. Pass through jugular
  4. Descends through neck along carotid arteries and internal jugular vein in carotid sheath
  5. Through mediastinum
  6. Pierces diaphragm with esophagus
  7. Terminal br in abdomen
  8. Most extensive distribution
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23
Q

X br

A

Pharyngeal

Superior laryngeal

  • Internal laryngeal
  • External laryngeal

Recurrent laryngeal

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24
Q

Pharyngeal plexus components

A

IX - glossopharyngeal n.

X - vagus n.

XI - accessory n., cranial part

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25
Q

X lesions

A

Soft palate

  • Paralyzes larynx muscles ipsilateral of lesion
  • Uvula deviates AWAY from lesion

Larynx

  • Paralyze larynx mm. ipsilateral of lesion
  • Unilateral = hoarseness
  • Bilateral = dyspnea
26
Q

Which cranial nn. travel through cavernous sinus?

A

III

IV

V1, V2

VI

27
Q

6 major br. of cervical plexus? What CN are they associated with?

A
  1. Great auricularis n.
  2. Supraclavicular n.
  3. Phrenic n.
  4. Lesser occipital n.
  5. Ansa cervicalis
  6. Transverse cervical n.

XII

28
Q

What are the major cutaneous br?

A
  • Lesser occipital n.
    • C2
  • Great auricular n.
    • C2, C3
  • Transverse cervical n.
    • C2, C3
  • Supraclavicular n.
    • C3, C4
29
Q

What is Erb’s pt?

A

Where 4 br. of cervical plexus (cutaneous br) emerge from behind SCM

LGTS

Surgical landmark

30
Q

Phrenic n.

A

C3, C4, C5 keep the diaphragm alive

Runs along anterior scalene, deep to carotid sheath

Mixed n.

31
Q

Ansa cervicalis

A

Motor

Loop of n. fibers

  • Superior - C1
  • Inferior - C2, C3

Travel WITH CN XII

Innervates 3 of 4 infrahyoid mm.

  • Omohyoid
  • Sternohyoid
  • Sternothyroid
32
Q

I

A
  1. Olfactory nn.
  2. Pass through cribiform plate
  3. Olfactory bulb
  4. Olfactory tract
  5. Olfactory area of cerebral cortex (temporal lobe)
33
Q

I lesions

A

Torn dura mater near cribiform plate = leaking CSF, “runny nose” after trauma

Torn olfacotry neurons

34
Q

II

A
  1. Rods and cones to ganglion cells o retina
  2. Passes through optic canal
  3. Optic chiasm
  4. Optic tract (medial fibers switch, lateral fibers stay on same side)
  5. Lateral geniculate body (thalamus)
  6. Visual cortex of cerebrum (occipital lobe)
35
Q

II lesions

A

Optic n. - complete blindness

Optic chiasm - bitemporal hemianopsia

Optic tract - homonymous hemianopsia

36
Q

VII

A
  1. Two sets of sensory fibers = vestibular and cochlear
  2. Leave anterior surface pons (near PMJ)
  3. Cross posterior cranial fossa
  4. IAM with facial n.
37
Q

VIII lesions

A

Acoustic neuroma

  • Benign Schwann cell tumor
  • Hearing loss and gait ataxia
  • Can block CSF drainage of 4th ventricle = hydrocephaly
    • Vomiting, loss of consciousness, death
38
Q

IV

A
  • Most slender n.
  • Posterior surface of midbrain
  • Middle cranial fossa
  • Lateral cavernous sinus
  • Superior orbital fissure
  • Superior oblique
39
Q

IV lesions

A

Diplopia

Eye is adducted and elevated (in and up)

40
Q

VI

A
  1. Anterior surface of pons, PMJ
  2. Passes forward with IC artery through cavernous sinus
  3. Enters orbit through superior orbital fissure
  4. Lateral rectus
41
Q

VI lesions

A

Diplopia

Medial strabismus

42
Q

XI

A
  1. Cranial root: anterior surface of medulla
  2. Runs laterally in posterior cranial fossa and joins spiral root
  3. Spinal root: anterior gray horn of upper 5 segments of spinal cord
  4. Ascends along spinal cord
  5. Enters skull through foramen magnum
  6. Turns laterally to join cranial root
  7. Roots unite, leave skull via jugular foramen, roots separate
    1. Cranial joins vagus (pharyngeal plexus)
    2. Spinal joins SCM and traps
43
Q

XI lesions

A

Partial paralysis of traps

  • Drooping of shoulder on affected side
  • Also innervated by C3-C5

Complete flaccid paralysis of SCM

  • Torticollis (wry neck)
    • Unilateral injury, cannot turn neck to opposite side
    • Bilateral, cannot hold head up
  • Only innervated by XI
44
Q

XII

A
  1. Anterior surface of medulla
  2. Rootlets join together to form XII
  3. Travel through hypoglossal canal
  4. Enter root of tongue superior to hyoid bone and lateral to hyoglossus
45
Q

XII lesions

A

Supranuc (brain) - contralateral paralysis

Peripheral (after brainstem) - ipsilateral paralysis if lesion is on XII

46
Q

Trigeminal sensory nuc (V, VII, IX, X): mesencephalic

A

Mesencephalic

  • Midbrain
  • Located at CN V entry
  • Proprioreceptive input from joints, muscles of mastication, teeth, periodontium
  • Sensory limb of jaw jerk reflex, force of bite, projects to motor nucleus of V
47
Q

Trigeminal sensory nuc (V, VII, IX, X): Chief

A

Chief - main, pontine, primary, principle TSN

  • Pons
  • Lateral to motor nuc
  • 2 pt discrimination or touch and pressure sensations from face, scalp, oral cavity, nasal cavity, dura
48
Q

Trigeminal sensory nuc (V, VII, IX, X): Spinal

A

Spinal TSN (descending)

  • Spinal cord to pons
  • Continuation of chief TSN
  • Pain and T sensations from face
49
Q

V

A

Largest CN

  1. Anterior pons
    1. Small motor root and large sensory root
  2. Posterior cranial fossa
  3. Apex of petrous part of temporal bone in middle cranial fossa
  4. Sensory root forms trigeminal gang
  5. V1, V2, V3 branch from gang
    1. V1 - only S
      1. Cavernous sinus
      2. Superior orb fiss
    2. V2 - only S
      1. Cavernous sinus
      2. F. rotundum
    3. V3 - both S and M
      1. F. ovale
50
Q

What does V1 branch off into?

A
  • Nasociliary n.
    • Posterior ethmoid n.
    • Anterior ethmoid n.
      • External nasal n.
    • Infratrochlear
    • Long ciliary n.
    • Short ciliary n (via ciliary gang)
  • Frontal n.
    • Supraorbial n.
    • Supratrochlear n.
  • Lacrimal n.
51
Q

Parasympathetic innervation of lacrimal gland

A

Pre-gang

  • Super sal. nuc
  • GP n. of VII
  • Joins with DP (symp) to form vidian n. (nerve of pterygoid canal)

Post-gang

  • Pterygopalatine gang
  • Hitch hikes on V2 zygomatic n.
  • Communicating br
  • Hitchhikes on V1 lacrimal n.
52
Q

What does V2 branch off into?

A
  • Zygomatic n.
    • (Comm to lacrimal n.)
    • Zygomaticotemporal n.
    • Zygomaticofacial n.
  • Infraorbital n.
    • (Pterygopalatine ganglion)
      • Lesser (posterior) palatine n.
      • Greater (anterior) palatine n.
    • Nasopalatine
    • PSA n.
    • MSA n.
    • ASA n.
    • Palpebral n.
    • Nasal n.
    • Superior labial n.
53
Q

What does V3 branch off into?

A
  • Meningeal
  • Auriculotemporal n.
  • Massteric
    • TT
    • TVP
    • Medial pterygoid
    • Lateral pterygoid
    • Buccal
    • Deep temporal nn. - ant. and post.
  • Lingual
    • (Submandibular gang)
    • Inferior alvolar n.
      • Incisive n.
      • Mental n.
  • Mylohyoid
54
Q

Trigeminal neuralgia

A

AKA tic douloureux

  • Pain in V2, V3, rarely V1
    • 1-2 min
    • Initiatied by stimulus
  • 5th-6th decades
  • Usually unilateral
    • Bilateral = MS
  • Unknown cause
  • Tx
    • Anticonvulsants
    • Neurosurgery
55
Q

Horner’s

A

PAM is Horny - V

Interruption of sympa nerve supply

Causes

  • Stroke
  • Neck trauma
  • Carotid artery injury
  • Pancoast tumors

PAM - signs/symptoms

  • Ptosis
  • Anhidrosis
  • Miosis - dilator pup. m. paralyzed
56
Q

Corneal reflex

A

V

AKA blink reflex to protect eye

Stimulated by cornea - light, touching it

Sensory - nasociliary V1

Motor - Temporal and zygomatic branches of VII

57
Q

Cough reflex

A

Cough receptors in resp tract - mechanical and chemical stimuli

Sensory

  • X (internal laryngeal n.)

Motor

  • X (recurrent laryngeal n.)
  • Phrenic n.
  • Intercostal m.
58
Q

Gag reflex

A

AKA pharyngeal reflex

Contraction of back of throat stimulated by touching back of tongue, uvula, tonsils

Sensory

  • Primarily IX
    • Touching soft palate, V

Motor

  • X
59
Q

Pupillary light reflex

A

Miosis - constriction

Mydriasis - dilation

Sensory - II

Motor - III (symp and para)

60
Q

Lens accommodation

A

Sensory - II

Motor - III (para)

61
Q

Baroreceptor reflex

A

Carotid sinus and arch

Sensory

  • Carotid sinus, IX
  • Aortic arch, X

Motor

  • Symp and para
62
Q

Jawjerk reflex

A

AKA masseter reflex

Stretch reflex - Testing V

Mandible is tapped at a downward anglle below lips with mouth slightly open - masseter should jerk upwards

Sensory - V3

Motor - V3