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Step 1 > Neurology - CN, tracts > Flashcards

Neurology - CN, tracts Flashcards

0
Q

CN II

A

Optic nerve: sight

  • optic nerves converge to form optic chiasm then goes on as optic tract
  • synapse on LGN
  • Middle cranial fossa, sphenoid bone - optic canal + opthalmic artery and centra retinal vein
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1
Q

CN I

A

Olfactory nerve ( bulb + tract)

  • only CN nerve that bypasses thalamic relay to cortex
  • synapses directly in the uncus
  • anterior fossa, cribriform plate
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2
Q

CN III

A

Oculomotor nerve: Motor

  • Oculomotor nucleus (midline midbrain): SR, IR, MR, IO, levator palpebrae (opens eyelid)
  • Nucleus of Edinger Westfall (pretectum of midbrain): preganglionic parasympathetic -> pupillary constriction (sphincter m.) & accomodation (ciliary m.)
  • Middle cranial fossa, sphenoid bone - superior orbital fissure + opthalmic vein
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3
Q

CN IV

A

Trochlear nerve: motor

  • Trochlear nucleus (midline midbrain): SO
  • Middle cranial fossa, sphenoid bone –> superior orbital fissure
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4
Q

CN V

A

Trigeminal nerve: Both
-V1: opthalmic sensation; superior orbital fissure
-V2: maxillary sensation; foramen rotundum
-V3: mandibular sensation + motor to muscles of mastication + somatosensory of anterior 2/3 of tongue; formen ovale
Trigeminal nuclei: Trigeminal motor nucleus (midline pons) = mastication; Spinal nucleus (lateral pons/medulla/upper spine) = Protopathic; Main sensory nucleus (lateral pons = sonsory

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5
Q

CN VI

A

Abducens: motor
Abducens nucleus: LR
-Middle cranial fossa, sphenoid bone–> superior orbital fissure

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6
Q

CN VII

A

Facial nerve: Both

  • Facial nucleus (midline pons): facial movement, closes eyelid, stapedius muscle in the ear
  • Nucleus solitarius (lateral pons): anterior 2/3 taste
  • Superior salvatory nucleus: lacrimation & salivation (submandibular and sublingual glands
  • Posterior cranial fossa, temporal bone –> internal acoustic meatus
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7
Q

CN VIII

A

Vestibulocochlear nerve: sensory

  • Vestibular nucleus (lateral pons/medulla): balance
  • Cochlear nucleus (lateral pons): hearing
  • posterior cranial fossa, temporal bone–> internal acoustic meatus
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8
Q

CN IX

A

Glossopharyngeal nerve: both

  • Nucleus ambiguus (lateral medulla): stylopharyngeus m. (elevates pharynx and larynx) = swallowing
  • Nucleus solitarius (lateral pons) : taste & somatosensory from from posterior 1/3 of tongue, carotid body monitoring
  • Inferior salivatory nucleus: (preganglionic parasympathetic) salivation of parotid gland
  • Posterior fossa, temporal bone –> jugular foramen
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9
Q

CN X

A

Vagus nerve: Both

  • Nucleus solitarius (lateral pons): taste of epiglottis, barorecptors of aortic arch, thorachoabdominal viscera (lungs, gut distention)
  • Nucleus ambiguus (lateral medulla): motor innervation of pharynx, larynx and upper esophagus = talking, swallowing, coughing, midline uvula
  • Dorsal motor nucleus (midline low pons/upper medulla): pre-ganglionic parasympathetic fibers to heart, lungs, and upper GI
  • Posterior fossa, temporal bone–> jugular foramen
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10
Q

CN XI

A

Accessory nerve: motor
-Accessory nucleus: motor to SCM, trapezius = turning head, shoulder shrugging
-Posterior fossa, temporal bone, jugular foramen
Note spinal roots of Xi exit through foramen magnum

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11
Q

CN XII

A

Hypoglossal nerve: motor

-hypoglossal nucleus (midline medulla): tongue movement

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12
Q

What cranial nerves arise from the midbrain?

A

III, IV

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13
Q

What cranial nerves arise from the pons?

A

V-VIII

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14
Q

What cranial nerves arise from the medulla?

A

IX, X, XII

Recall: XI arise from the spinal cord

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15
Q

Nucleus solitarius

A

visceral sensory information - taste, baroreceptors, gut distention
-CN VII, IX, X

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16
Q

Nucleus ambiguus

A

:Lateral medulla; motor innervation of pharynx, larynx, and upper esophagus = swallowing, palate elevation
-CN IX, X, XI (cranial portion)

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17
Q

Dorsal motor nucleus

A

:midline low pons/upper medulla; sends autonomic pre-ganglionic parasympathetic fibers to heart lungs and upper GI
-CN X

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18
Q

Contents of optic canal

A

CN II, opthalmic artery, central retinal vein

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19
Q

Contents of superior orbital fissure

A

CN III, IV, V1, VI, opthalmic vein, sympathetic fibers

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20
Q

Significance of foramen spinosum

A

external carotid–> maxillary artery –> middle meningeal artery which enters the skull through the foramen spinosum of the temporal bone to supply the meninges and calvarium

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21
Q

Contents of the jugular foramen

A

CN IX, X, XI, jugular vein

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22
Q

What runs through the foramen magnum?

A

Spinal roots of CN XI, brain stem, vertebral arteries

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23
Q

Corneal reflex

A

V1 opthalmic (nasocilary branch) + VII (orbicularis oculi)

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24
Q

Lacrimation

A

V1 + VII

Note: loss of corneal reflex does not also cause loss of emotional tears

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25
Q

Jaw Jerk

A

V3 (sensory- muscle spindle from masseter) + V3 (motor- masseter)

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26
Q

Pupillary light reflex

A

II + III

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27
Q

Gag reflex

A

IX + X

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28
Q

CN V motor lesion

A

Jaw deviates toward side of lesion due to unopposed force from the opposite pterygoid muscle.

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29
Q

CN X lesion

A

Uvula deviates away from the side of the lesion. Weak side collapses and uvula points away

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30
Q

CN XI lesion

A

weakness turing head to contralateral side of lesion (SCM). Shoulder droop on side of lesion (trapezius)

Note: left SCM contracts to turn head to the right

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31
Q

CN XII lesion (LMN)

A

tongue deviates toward the side of the lesion due to weakened tongue muscles on the affected side.

32
Q

CST

A

Extends from motor cortex -> corona radiata-> internal capsule (posterior limb) -> cerebral peduncle-> basis pontis -> decussate at caudal pyramids -> continue as lateral CST in lateral

  • lateral CST organized laterally to medially : LTACervical
  • anterior CST
33
Q

Epicritic sensation

A

: Receptors are muscle spindles, golgi tendon organs, pacinian corpuscles, meisseners corpuscles, etc.; detect pressure, vibration, touch proprioception

  • primary sensory cell bodies in the DRG, axons travel in:
    1. Fasiculus gracilus (below T6 = lower body, legs)
    2. Fasiculus cutneatus (above T6= upper body, arms)
  • synapse in nucleus grasiclus/cuneatus in medulla and decussate –> medial lemniscus -> VPL
34
Q

Protopathic sensation

A

: receptors are C fibers and A-delta fibers that detect pain and temperature

  • cell bodies in the DRG, axons enter spinal cord synase on rexed laminae ->decussate @ anterior white commissure -> spinothalamic tract -> spinal lemniscus -> VPL
  • Lateral spinothalamic tract organized laterally to medially: LTACervical
  • anterior spinothalamic tract: crude touch and pressure
35
Q

What thalamic nucleus mediates sensation of the face?

A

VPM –> primary motor cortex

  • Protopathic (pain & temp) mediated by spinal trigeminal nucleus
  • Epicritic mediated by main nucleus of trigeminal nerve
36
Q

What thalamic nucleus mediates vision?

A

LGN –> primary visual cortex @ calcarine sulcus

“lateral for light”

37
Q

What thalamic nucleus mediates hearing?

A

MGN -> temporal lobe (transverse gyrus of Heschl)

“Medial for music”

38
Q

What thalamic nucleus mediates motor function?

A

VL

-basal ganglia and cerebellum communicate via VL to thalamus which relays to motor cortex

39
Q

What thalamic nucleus mediates general epicritic sensory?

A

VPL

Recall: epicritic = pressure, vibration, touch, proprioception

40
Q

What thalamic nucleus mediates genera protopathic sensory?

A

VPL

Recall: protopathic= pain, temperature, crude touch, pressure

41
Q

Conductive hearing loss

A

Rinne: bone> Air
Weber: localizes to affected ear
“goes to bad ear, but its not too bad just conductive hearing loss”

42
Q

Sensorineural hearing loss

A

Rinne: air> bone
Weber: localizes to unaffected ear
“ goes to good ear, but that not good its sensorineuro loss”

43
Q

Paralysis of the lower face with forehead sparred. Where is the lesion?

A

contralateral UMN lesion

  • CBT provides contralateral innervation to upper and lower portion of facial nerve; CBT on ipsilateral side only provides innervation to upper portion
  • if contralateral CBT lesioned = denervated lower portion of CN VII
44
Q

Paralysis of upper and lower portion of the face. Where is the lesion?

A

Ipsilateral CN VII (LMN lesion)

45
Q

Peripheral paralysis of one side of face - drooping smile and inability to close eye on involved side. Diagnosis? Treatment?

A

: Bell’s palsy; destruction of facial nerve nucleus

  • can occur idiopathically and recover in most cases
  • Associated with Lyme disease, HSV, herpes zoster, sarcoidosis, tumors, and diabetes
  • treatment: corticosteroids
46
Q

Muscles that close the jaw

A

Masseter, temporalis, medial pterygoid

-innervated by V3

47
Q

Muscles that open the jaw

A

lateral pterygoid

-innervated by V3

48
Q

Pupillary control miosis

A

: constriction mediated by parasympathetic
1st neuron: nucleus of Edinger Westfall –> ciliary ganglia via CN III
2nd neuron: short ciliary nerves to pupillary sphincter muscles

49
Q

Pupillary control mydriasis

A

: dilation mediated by sympathetic
1st neuron: hypothalamus to ciliospinal center of Budge (C8-T2) and synapses in lateral horn
2nd neuron: exit at T1 to superior cervical ganglion (travels along cervical sympathetic chain near lung apex, subclavian vessels)
3rd neuron: plexus along internal carotid through cavernous sinus, enters orbit as long ciliary nerve to pupillary dilator muscle

50
Q

Horner syndrome

A

:Ptosis, anhidrosis, miosis

-associated with lesion of spinal cord above T1

51
Q

Pupil constricts to consensual but not direct light. Where is the lesion?

A

CN II lesion = Marcus Gunn pupil

52
Q

Pupil fails to constrict to direct or consensual light. Where is the lesion?

A

CN III = hutchinson syndrome

also associated may be with dilated pupil + ptosis + lack of accommodation + down and out gaze

53
Q

Patient with ptosis. How do you know its parasympathetic or sympathetic lesion?

A

Look at the pupils:

  • Dilated = parasympathetic lesion
  • constricted (pinpoint) = sympathetic lesion (above T1)
54
Q

Explain the pupillary light reflex.

A

light in either retina sends a signal via CN II to pretectal nuclei in midbrain that activates bilateral nucleus of edinger westfall = pupils contract bilaterally –> consensual reflex

55
Q

Marcus Gunn Pupil

A

Deafferented (CN II lesion) that constricts to consensual light but not direct light

56
Q

Patient presents with ptosis, down and out gaze

A

CN III motor lesion

  • affected primarily by vascular disease (DM) due to decreased diffusion of oxygen and nutrients to the interior fibers from compromised vasculature that resides on outside of nerve
  • Note: motor fibers are centrally located within CN III
57
Q

Patient has absent pupillary light reflex to direct and consensual light & blown out pupil

A

CN III parasympathetic lesion; often accompanied by ptosis and down and out gaze ( motor portion)

  • fibers in the periphery are 1st affected by compression (PICA aneurysm, uncal herniation)
  • Note parasympathetic fibers are at the periphery of CN III
58
Q

Right anopia, where is the lesion?

A

right cranial nerve II ( nerve portion)

59
Q

Bitemporal hemianopia, where is the lesion?

A

optic chiasm

60
Q

Left homonymous hemianopia, where is the lesion?

A

RIGHT optic tract, LGN, or optic radiations

61
Q

Left upper quandrantic anopia, where is the lesion?

A

right temporal lesion (meyers loop - optic radiations) MCA territory

62
Q

Left lower quandrantic anopia, where is the lesion?

A

Right parietal lesion, MCA territory

63
Q

Left hemianopia with macular sparring, where is the lesion?

A

Right occipital lobe lesion, PCA territory

64
Q

Describe the pathway of conjugate gaze when looking to the left.

A

Saccade- Right frontal eye field activates the left PPRF that stimulates the left CN VI (lateral rectus) –> right MLF to stimulate the right CN III (medial rectus)

65
Q

C fibers

A

:free nerve endings; slow unmyelinated fibers, mediate pain and temperature
-located on all skin, epidermis, some viscera

66
Q

A delta fibers

A

free nerve endings; fast, myelinated fibers mediate pain and temperature
-located on all skin, epidermis, some viscera

67
Q

Meissner corpuscles

A

:large, myelinated fibers, adapt quickly mediate dynamic, fine/light touch; position sense
-located on glabrous (hairless) skin

68
Q

Pacinian corpuscles

A

large, myelinated fibers; adapt quickly mediate vibration, pressure
-located in deep skin layers, ligaments, and joints

69
Q

Merkel discs

A

large myelinated fibers; adapt slowly; mediate pressure, deep static touch
-located in the basal epidermal layer, hair follicles

70
Q

Hypothalamus functions

A 
"TAN HATS"
Thirst and water balance 
Adenohypophysis control (regulates anterior pituitary) 
Neurohypophysis releases hormones produced in hypothalamus 
Hunger 
Autonomic regulation 
Temperature regulation 
Sexual urges
71
Q

What are the inputs to the hypothalamus?

A

Circumventricular organs - not protected by BBB

“Mild SOAP”

72
Q

Where is ADH produced?

A

Supraoptic nucleus

73
Q

Where is oxytocin produced?

A

Paraventricular nucleus

74
Q

Lateral area of hypothalamus

A

Hunger

  • Destruction –> anorexia, failure to thrive (infants)
  • Inhibited by leptin
75
Q

Ventromedial area of hypothalamus

A

Satiety

  • destruction (craniopharyngioma) –> hyperphagia
  • Stimulated by leptin
76
Q

Anterior hypothalamus

A

Cooling, parasympathetic

“A/C”

77
Q

Posterior hypothalamus

A

heating, sympathetic

78
Q

Suprachiasmatic nucleus

A

circadian rhythm

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