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cranial nerves Flashcards

1
Q

what are the definitions of these terms:

  • afferent
  • efferent
  • somatic
  • visceral
A

Afferent = axons carrying nerve impulses towards the CNS –

  • afferents are sensory

Efferent = axons carrying nerve impulses away from the CNS –

  • efferents are motor

Somatic = EITHER sensory (afferent) innervation to skin or muscle

AND / OR motor (efferent) innervation to striated muscles

Visceral = sensory (afferent) or motor (efferent) innervation to visceral organs, glands, smooth muscle

  • In the case of motor = autonomic (sometimes called visceromotor)
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2
Q

what is meant by special and general?

A

General = sensory and motor functions

  • usual normal stuff
  • spinal

Special = basically only for special functions such as hearing, taste

  • cranial nerves have special functions
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3
Q

what is SSA?

A

Special Somatic Afferent -

  • sensory information for the senses of hearing and balance

CN VIII

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4
Q

what is SVA?

A

Special Visceral Afferent -

  • sensory for the sense of taste

CN VII, IX, X

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5
Q

what is SVE

A

Special Visceral Efferent -

  • motor innervation
    • to striated muscles derived from the pharyngeal arches
      • i.e. face, mouth, pharynx, larynx.

CN V, VII, IX, X, XI

(sometimes called branchiomotor nerves/neurons)

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6
Q

which muscles are derived from which pharyngeal arches?

A

1 - muscles of mastication

2 - muscles of facial expression, stylohyoid, posterior belly of digastric

3 - stylopharyngeus

4 - soft palate muscles

5 -

6 - muscles of larynx

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7
Q

how are the general (spinal) nerve associated in the spinal cord?

A

the spinal nerves are associated with columns

afferents :

  • columns contain second order sensory neurons
    • these are innervated by DRG afferents
  • Columns are innervated by the GSA, GVA fibres which synapses with interneurons to continue the signal

efferents :

  • columns contain lower motor neuron cell bodies
    • these project to innervate
      • skeletal muscles GSE
      • autonomic nuclei GVE
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8
Q

what are the components of spinal nerves?

draw and label

A

Motor and autonomic join spinal nerves

  • Sensory also
  • GSA and GVA
    • axon of the sensory neuron which synapses with DRG neurons
    • these innervate second order sensory neurons - (which are in the columns?)
    • connect to thalamus
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9
Q

how are the cranial nerve components arranged in the midbrain and hindbrain?

A

Cranial nerve components have columns of neurons in midbrain and hindbrain

GVA and SVA are merged into one column

all autonomic motor axons associated with CN are parasympathetic

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10
Q

which fibres contain lower motor neurons?

which fibres contain second order sensory neurons?

A

Fibres whose nuclei contain lower motor neurons :

  • GSE
  • GVE

Fibres whose nuclei contain second order sensory neurons :

  • GVA
  • SVA
  • GSA
  • SSA
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11
Q

draw the locations of the soma of the GSE cranial nerve nuclei

A
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12
Q

draw the locations of the soma of the GVE cranial nerve nuclei

A
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13
Q

draw the locations of the soma of the GVE cranial nerve nuclei

A

III

  • involved in pupillary reflex

VII

  • superior salivatory nucleus
  • what projections ^

IX

  • interior salivary nucleus
  • what projections ^

X

  • project to plexi – not ganglions
  • to large parts of the body
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14
Q

draw the locations of the soma of the GVA and SVA cranial nerve nuclei

A

NTS receives innervation from primary afferent sensory neurons

  • Contains cell bodies of second order sensory neurons

Visceral sensory division

  • receive sensory information from afferents from IX and X
    • includes blood pressure, stretch

Taste

  • receive from afferents associated with CN VII IX X
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15
Q

draw the locations of the soma of the GSA cranial nerve nuclei

A

GSA cranial nerve nuclei receive innervation from primary afferent sensory neurons

  • and contain cell bodies of second order sensory neurons

Only CN V

  • 3 nuclei
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16
Q

draw the locations of the soma of the SSA cranial nerve nuclei

A
17
Q

describe cranial nerve I

A

olfactory

  • Not a true cranial nerve
  • Just nerve tract
    • Outgrowth of forebrain
18
Q

describe cranial nerve II

A

optic

  • Not true cranial nerve
    • Just nerve tract
    • Outgrowth of forebrain
  • Joins retina with forebrain
19
Q

describe cranial nerve III

A

oculomotor

  • GSE to most extrinsic eye muscles
    • All but those innervated by IV and VI
  • Also carries GVE (parasympathetic) to ciliary muscles and pupillary constrictor via the ciliary ganglion
20
Q

how are the extrinsic eye muscles innervated?

A
  • CN IV GSE to superior oblique eye muscle
  • CN VI GSE to lateral rectus eye muscle
  • CN III GSE to other extrinsic eye muscles
21
Q

describe cranial nerve IV

A

trochlear

  • GSE to superior oblique eye muscle
22
Q

describe cranial nerve VI

A

abducens

  • GSE to lateral rectus eye muscle
23
Q

describe cranial nerve V

A

trigeminal

  • GSA
    • sensation from face, mouth, nasal cavity, teeth, dura, anterior 2/3 tongue
  • also carries CN VII to targets
    • lacrimal nerve carries GVE facial nerve fibres to lacrimal gland
    • lingual nerve carries parasympathetic facial nerve fibres to SL and SM salivary glands
    • SVA fibres to tongue
  • GVE innervation
    • ​muscles derived from 1st pharyngeal arch
      • mastication
      • biting
      • swallowing
  • SVE motor neurons in mandibular division innervate muscles
    • tensor tympani
      • dampens chewing sounds
    • tensor velo palatini
      • tenses soft palate and opens eustachian tube for swallowing
24
Q

which facial muscles are involved in :

mastication

swallowing

A
25
Q

describe cranial nerve VII

A

facial

  • SVA
    • Taste from 2/3 anterior tongue and soft palate
    • Neuron soma found in geniculate ganglion
      • Central axons project to NTS
  • GVE preganglionic parasympathetic to :
    • Oral / nasal mucosa & lacrimal glands
      • Via pterygopalatine ganglion
    • Sublingual and submandibular glands
      • Via submandibular ganglion
  • SVE
    • To 2nd arch musculature - facial expression
26
Q

describe cranial nerve VIII

A

vestibulocochlear

  • SSA
    • Innervate organ of corti within cochlear
      • Have soma in spiral ganglion
    • Innervate vestibular canals
      • Have some in vestibular ganglion (scarpa’s)
  • The vestibulo cochlear nerve exits through petrous temporal bone through internal auditory meatus before entering brainstem with CN VII
27
Q

describe cranial nerve IX

A

glossopharyngeal

  • SVA
    • Taste to posterior 1/3 tongue
    • Found in petrosal ganglion
    • Central axons project to NTS
      • To taste division
  • GVA
    • To carotid sinus/body, post 1/3 tongue and pharynx
      • Carotid sinus
        • Measurement of blood pressure
        • Blood-gas measurement
    • Found in petrosal ganglion
    • Central axons project to NTS
      • To taste visceral sensory division
  • GVE
    • To parotid salivary gland (parasym)
      • Are preganglionic parasympathetic fibres
      • Have postganglionic fibres in otic ganglion
  • SVE
    • To stylopharyngeus from nucleus ambiguus
      • Muscle elevates pharynx for swallowing and gagging
28
Q

describe cranial nerve X

A

vagus

  • SVA
    • taste to epiglottis
    • afferents - cell body found in nodose ganglion
      • terminate in NTS
  • GVA sensation –
    • aortic body, larynx, pharynx, trachea, heart, lungs, gut etc
    • Throughout the body
    • Aortic arch
      • Contains baroreceptors - blood pressure measurement
      • Contains chemoreceptors - blood oxygen conc measurement
    • afferents - cell body found in nodose ganglion
      • terminate in NTS
  • GVE
    • from dorsal motor nucleus to heart, and smooth muscle of bronchioles and gut
    • preganglionic parasympathetic from dorsal motor nucleus of X to postganglionic neuron plexi in;
      • heart, bronchioles of the lung, GI tract, pancreas etc.
  • SVE
    • from nucleus ambiguus to pharynx and larynx.
29
Q

describe cranial nerve XI

A

spinal accessory

  • Motor roots at C1-C5 coalesce to form CN XI
  • Enters skull through foramen magnum
  • Emerges from jugular foramen
  • SVE
    • SCM innervation and rotates head
      • Sensory innervation of SCM = C2 spinal nerve
    • Upper trapezius innervation
      • Controls shoulder blades
      • Sensory innervation = C3,4 spinal nerves
30
Q

describe cranial nerve XII

A

hypoglossal

  • GSE
    • to intrinsic and extrinsic tongue musculature
      • (not palatoglossus = X)

z basic sciences (21 decks)

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