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► Med - Neuroanatomy > Exam #2: Cranial Nerves I > Flashcards

Exam #2: Cranial Nerves I Flashcards

1
Q

In regards to the functional components of cranial nerves, what is the difference between general & special fibers?

A

General= functional components present in typical spinal nerves AND cranial nerves

Special= functional components present ONLY in cranial nerves

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2
Q

What does GSA stand for? What functional components are carried by these fibers?

A

“General Somatic Afferent”

  • Touch
  • Pressure
  • Pain
  • General propcioception
  • Temperature

*All FROM somatic structures

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3
Q

What does GVA stand for? What functional components are carried by these fibers?

A

“General Visceral Afferent”

  • Pressure
  • Pain

*All FROM visceral structures

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4
Q

What does GVE stand for? What functional components are carried by these fibers?

A

“General Visceral Efferent”

  • Motor impulses TO visceral smooth muscle/ cardiac muscle
  • PNS**
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5
Q

What does GSE stand for? What functional components are carried by these fibers?

A

“General Somatic Efferent”

- Motor impulses TO skeletal muscles

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6
Q

What does SVA stand for? What senses are these fibers associated with?

A

“Special Visceral Afferent”

  • Olfaction
  • Gustation
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7
Q

What does SSA stand for? What senses are these fibers associated with?

A

“Special Somatic Afferent”

  • Sight
  • Hearing
  • Equilibrium
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8
Q

What does SVE stand for? What do SVE fibers innervate?

A

“Special Visceral Efferent”

- Skeletal muscle (derived from the pharyngeal arches)

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9
Q

What cranial nerves contain GSE fibers?

A

III, IV, VI, XII

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10
Q

What are somatic efferent nerves?

A

Cranial nerves that carry GSE fibers

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11
Q

What functional component is CN I associated with?

A

SVA (smell)

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12
Q

What cranial nerves carry SVA-taste-fibers?

A

VII
IX
X

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13
Q

What are branchiometric muscles?

A

Striated muscles of the head and neck that developmentally come from branchial arches i.e. pharyngeal arches.

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14
Q

What cranial nerves are referred to as the “branchiomeric nerves?”

A

V
VII
IX
X

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15
Q

Which cranial nerve is the only cranial nerve to have a true pain nucleus?

A

Trigeminal (V)

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16
Q

What is the function of CN I? What type of fibers does the Olfactory Nerve have?

A

Smell i.e. “Olfactory Nerve”

- SVA

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17
Q

What is the olfactory mucosa?

A

Most superficial layer of the olfactory epithelium

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18
Q

Where are the olfactory nerves located?

A
  • Lateral wall of the nasal cavity

- Nasal septum

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19
Q

What is the function of the basal cells in the olfactory epithelium?

A

Stem cell precursors of olfactory receptors

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20
Q

What is the function of the sustentacular cells in the olfactory epithelium?

A

Support

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21
Q

What is the function of Bowman’s glands in the olfactory epithelium?

A

Secretion of serous fluid

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22
Q

What type of cells are olfactory receptors?

A

Modified bipolar neurons

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23
Q

What structure do the axons of the olfactory receptors pass through to enter the brain?

A

Cribriform plate of the ethmoid bone

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24
Q

What is unique about olfactory receptor cells?

A

1) Only neurons exposed to the exterior environment
2) Nerve cell bodies located in epithelium vs. ganglion
3) Regenerated every 30-60 days
4) Slowest conducting/ unmyelinated axons of the nervous system

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25
Q

What is the first order neuron of the olfactory pathway?

A

Olfactory receptor

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26
Q

What is the second order neuron of the olfactory pathway?

A

Olfactory bulb

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27
Q

What do the axons of the olfactory receptors bundle together to form?

A

Olfactory fila, which collectively= CN I

**It is the olfactory fila that actually pass through the cribriform plate

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28
Q

Where do the axons of the olfactory bulbs run? What structure do these neurons give off collaterals to?

A

Axons run in the olfactory tracts & give off collaterals to the “Anterior Olfactory Nucleus”

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29
Q

What do the olfactory tracts divide into?

A

Olfactory stria (medial & lateral)

*****Note that the lateral olfactory stria is the major pathway of the olfactory system

30
Q

Where do the olfactory stria project? Why is this unusual?

A

Olfactory stria bypasses the thalamus & project to the:

1) Amygdala 
2) Olfactory cortex
31
Q

Why is it important that the Olfactory Tract projects to the Amygdala?

A

The amygdala functions in learning, memory, emotions, & drives
- Each scent has an “emotional tag” b/c of this projection.

32
Q

Where does the primary olfactory cortex project?

A

1) Hypothalamus= endocrine & autonomic functions
2) Amygdala
3) Cortical areas associated with memory
4) Olfactory association cortex

33
Q

What is a common cause of damage to the axons of olfactory receptors?

A

Head trauma, which causes:

1) Direct trauma to the ethmoid bone
2) Shearing forces on the axons of the olfactory receptors as they pass through the cribriform plate in the ethmoid bone

34
Q

What happens as a result of a lesion to the axons of the olfactory receptors?

A

Ansomia= total loss of smell

Hyposmia= partial loss of smell

Parosmia= distorted perception of smell

35
Q

What are the receptors for the visual system?

A

Rods

Cones

36
Q

What is the first order neuron for the visual pathway?

A

Bipolar neurons in the retina that rods & cones synapse on

37
Q

What are the second order neurons for the visual system?

A

Ganglion cells residing in the retina

38
Q

Where do the axons of the ganglion cells converge?

A

At the back of the eyeball to form the Optic nerve (CN II)

39
Q

What is unique about the optic nerve?

A

The optic nerve is considered to be part of the CNS & is myelianted by oligodendrocytes

40
Q

Clinically, why is it important that the optic nerve is myelinated by oligodendrocytes?

A

Multiple Sclerosis–optic will be affected

41
Q

What is the difference between the optic nerve & optic tracts?

A
  • Optic nerve is formed by the axons of ganglion cells from the retina
  • Optic nerves decussate at the optic chiasm
  • After the optic chiasm, referred to as the optic tracts
42
Q

Where do the axons of the 2nd order neurons (ganglion cells) of the optic tract terminate?

A

1) Lateral geniculate nucleus (LGN) of the thalamus*****
2) Superior colliculus
3) Pretectal area
4) Hypothalamus

43
Q

What is the function of the superior colliculus?

A

Reflex head & eye movements in response to sensory stimulation

44
Q

What is the function of the pretectal area?

A

Pupillary constriction reflex

45
Q

What are the third order neurons of the visual pathway?

A

LGN

46
Q

What do the axons of the LGN give rise to?

A

Geniculocalcarine tracts that go to the primary visual cortex of the occipital lobe

47
Q

What artery supplies the visual cortex (calcarine sulcus)?

A

Mostly the Posterior cerebral artery (PCA)

*****MCA sends anastamosis

48
Q

If a thrombus occludes the right PCA, how will the lesion manifest?

A

“Left homonymous hemianopia w/ macular sparing”

  • Left half of visual field in each eye
  • Macular region spared
49
Q

Why is there macular sparing in w/ PCA lesion?

A

Anastamosis from the MCA

50
Q

What are the functional components of CN XI?

A

SVE/GSE= Trapezius, SCM, laryngeal muscles

GP= general proprioception to Trapezius & SCM

51
Q

What fibers of CN XI supply the laryngeal muscles?

A

Abberant vagal fibers

52
Q

What nucleus do the abberant vagal fibers arise from? Where?

A

Nucleus ambiguious in the MEDULLA

53
Q

What nucleus do the fibers of CN XI arise from? Where?

A

Spinal accessory nucleus in the SPINAL CORD

54
Q

Describe the path of the Spinal Accessory Nerve from the spinal cord.

A

1) C1-C5/6 in cord
2) Enter foramen magnum
3) Join abberant vagal
4) Exit Jugular foramen
5) Innervation:
- Abberant vagal= laryngeal muscles
- Spinal accessory= SCM & Trapezius

55
Q

Which SCM contracts to turn the head to the right?

A

Left

56
Q

What happens when there is a Spinal Accessory nerve lesion?

A

Scapular winging

57
Q

How does lesion of the long thoracic nerve compare to lesion of the accessory nerve?

A

BOTH produce scapular winging, but each is more prominent with different actions:

  • LT= pushing against object & anterior elevation of affected arm
  • CN XI= ABduction of affected arm
58
Q

What functional component does CN XII contain?

A

GSE i.e. general somatic efferents or motor innervation to the intrinsic & extrinsic muscles of the tongue

59
Q

Where does the hypoglossal nerve originate?

A

Hypoglossal nucleus, which is located in the groove between the olive & the pyramid

60
Q

What are the manifestations of a lesion to CN XII at rest?

A
  • Hemiparalysis on ispsilateral side
  • Atrophy
  • Fasiculations
61
Q

What are the manifestations of a LMN lesion to CN XII w/ protrusion of the tongue?

A

Tongue deviation to SIDE OF LESION

62
Q

What is the manifestation of left optic neuritis or damage to the left optic nerve?

A

Total blindness in the left eye

63
Q

What is the manifestation of a lesion in the left angle of the optic chasma?

A

Ipsilateral Nasal Hemianopia

- No perception of left nasal field

64
Q

What is the manifestation of a bilateral ICA aneurism?

A

Binasal Heteronymous Hemianopia

- No perception of left or right nasal fields

65
Q

What is the manifestation of a pituitary tumor?

A

Bitemporal Heteronymous Hemianopia

- No perception of left or right temporal fields

66
Q

What is the manifestation of a lesion to the left optic tract?

A

Right Homonymous Hemianopia

67
Q

What is the manifestation of a lesion to the left Meyer’s Loop?

A

Right Upper Homonymous Quadrantanopia

- Right “Pie in the Sky” loss

68
Q

What is the manifestation of a lesion to the Inferior Division of the Geniculocalcarine Tract?

A

Right Lower Homonymous Quadrantanopia

- Right “Pie on the Floor” loss

69
Q

What is the general pattern for visual pathway lesions?

A
  • Optic Chiasm & Distal= Heteronymous

- Proximal to optic chiasma= Homonymous

70
Q

What is the manifestation of a lesion to all the left optic radiation fibers in the occipital lobe?

A

Right Homonymous Hemianopia

► Med - Neuroanatomy (36 decks)

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