Cranial Nerves Flashcards

1
Q

What are the reason nerves can be compressed?

A

Due to inflammation, tumours and fractures

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2
Q

What are all the classifications of fibres that cranial nerves can contain?

A

Somatic motor fibres

Visceral motor fibres

Visceral sensory

General sensory

Special sensory

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3
Q

What do somatic motor fibres do?

A

Supply striated muscle

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4
Q

What do visceral motor fibres of the cranial nerves do?

A

They are parasympathetic fibres and innervate smooth muscle and glands

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5
Q

What are the visceral sensory parts of the cranial nerves?

A

•- afferent inputs from pharynx, larynx, heart, lung, gut etc - not normally conscious

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6
Q

What are the general sensory cranial nerves responsible for?

A

•General sensory - afferent inputs (eg touch, temperature, pain) from skin & mucous membranes

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7
Q

What are the special sensory cranial nerves responsible for?

A

•Special sensory – taste, smell, vision, hearing & balance

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8
Q

What type of cranial nerve are the following?

A
  1. Afferent sensory
  2. Somatic motor (efferent)
  3. Autonomic motor (efferent)
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9
Q

Where are the olfactory receptors?

A

Receptors in olfactory epithelium of nasal cavity

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10
Q

Where do olfactory nerve fibres pass?

A

Olfactory nerve fibres pass through foraminifera in cribriform plate of ethmoid bone and enter olfactory bulb in the anterior cranial fossa

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11
Q

What are the components of the olfactory nerve?

A

–special sensory - smell

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12
Q

What does a fractured cribiform plate result in?

A

–fractured cribriform plate may tear olfactory nerve fibres causing anosmia

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13
Q

What is the pathway for the optic nerve?

A

Enters via optic canal, nerves join to form optic chiasm, fibres from medial (nasal) half of each retina cross to form optic tract

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14
Q

What are the components of the optic nerve?

A

–special sensory - vision

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15
Q

What is the effect of increase in CSF pressure?

A

Papilloedema

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16
Q

What is the pathway of the occulomotor nerve?

A

–emerges from midbrain and exits via superior orbital fissure

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17
Q

What are the components of the occulomotor nerve?

A

–somatic motor - extraocular muscles (superior, medial & inferior rectus and inferior oblique) and eyelid (levator palpebrae superioris)

–visceral motor - parasympathetic to pupil causing constriction and to ciliary muscle causing accommodation of the lens

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18
Q

What are the clinical applications of the occulomotor nerve?

A

–drooping of upper eyelid (ptosis)

–eyeball abducted and pointing down

–no pupillary reflex

–no accommodation of the lens

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19
Q

What is the pathway of the trochlear nerve?

A

–emerges from dorsal surface of the mid brain and exits via the superior orbital fissure

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20
Q

What are the components of the trochlear nerve?

A

–somatic motor - extraocular muscle (superior oblique turns eye downwards)

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21
Q

What are the clinical applications of trochlear nerve?

A

Diploplia when looking down

22
Q

What is the pathway of the abducent nerve?

A

–emerges between pons and medulla and exits exits via the superior orbital fissure

23
Q

What is the pathway of the abducent nerve?

A

Emerges between the pons and the medulla - exits via the superior orbital fissure

24
Q

What are the components of the abducent nerve?

A

Somatic motor - extraocular muscle (lateral rectus)

25
Q

What is the clinical application of the abducent nerve?

A

Medial deviation of the affected eye causig diplopia

26
Q

What is the pathway of the trigeminal nerve (ophthalmic)?

A

–emerges from the pons, travels through the trigeminal ganglion and exits via the superior orbital fissure

27
Q

What are the components of the trigeminal (ophthamic)?

A

–General sensory - from cornea, forehead, scalp, eyelids, nose and mucosa of nasal cavity and sinuses

28
Q

What is the pathway of the trigeminal (maxillary) CNV2?

A

–Emerges from the pons, travels through the trigeminal ganglion and exits via the foramen rotundum

29
Q

What are the components of the trigeminal (maxillary)?

A

–General sensory - from face over maxilla, maxillary teeth, temperomandibular joint, mucosa of nose, maxillary sinuses and palate

30
Q

What is the pathway of the trigeminal (mandibular)?

A

–emerges from the pons, travels through the trigeminal ganglion and exits via the foramen ovale

31
Q

What are the components of the trigeminal mandibular division?

A

–General sensory - from face over mandible, mandibular teeth, temperomandibular joint, mucosa of mouth & anterior 2/3rds of tongue

–Somatic motor - muscles of mastication, part of digastric, tensor veli palatinin & tensor tympani

32
Q

What is the clinical application of the trigeminal (mandibular)?

A

–paralysis of muscles of mastication

–loss of corneal or sneezing reflex

–loss of sensation in the face

–trigeminal neuralgia

33
Q

What is the pathway of the facial nerve?

A

–emerges between pons and medulla and exits via internal acoustic meatus, facial canal and stylomastoid foramen

34
Q

What are the components of the facial nerve?

A

–somatic motor - muscles of facial expression & scalp, stapedius of middle ear, part of digastric muscle

–visceral motor - parasympathetic innervation of submandibular & sublingual salivary glands, lacrimal glands, glands of nose & palate

–special sensory - taste from anterior 2/3rd of tongue & soft palate

–general sensory - from external acoustic meatus

35
Q

What is the clinical application of the facial nerve?

A

–most frequently injured - due to long pathway through bone

–Bell’s palsy - cannot frown, close eyelid, or bare teeth

36
Q

What is the pathway of the vestibulocochlear nerve?

A

Emerges from between the pons and the medulla and exits via the internal acoustic meatus, dividing into vestibular and cochlear nerves

37
Q

What are the components of the vestibulocochlear nerve?

A

–special sensory - vestibular sensation from semicircular ducts, utricle, saccule gives sense of position & movement

  • hearing from spiral organ (cochlea)
38
Q

What are the clinical applications of the vestibulocochlear nerve?

A

–tinnitus (ringing in the ears)

–deafness (conductive vs sensorineural)

–vertigo (loss of balance)

–nystagmus (involuntary rapid eye movements)

39
Q

What is the pathway of the glossopharyngeal nerve?

A

–emerges from medulla and exits via jugular foramen

40
Q

What are the components of the glossopharyngeal nerve?

A

–special sensory - taste from posterior 3rd of tongue

–general sensory - cutaneous sensations from middle ear and posterior oral cavity

–visceral sensory - sensation from carotid body & carotid sinus

–visceral motor - parasympathetic innervation of parotid gland

somatic motor - to stylopharyngeus, helps with swallowing

41
Q

What are the clinical applications of the glossopharyngeal nerve?

A

–loss of gag reflex and taste from back of tongue

–associated with injuries to CNs X and XI - jugular foramen syndrome

42
Q

What is the pathway of the vagus nerve?

A

–emerges from medulla and exits via jugular foramen, then everywhere!

43
Q

What are the components of the vagus nerve?

A

–special sensory - taste from epiglottis and palate

–general sensory - sensation from auricle, external acoustic meatus (facial nerve also supplies general sensory to the external acoustic meatus)

–visceral sensory - from pharnyx, larynx, trachea, bronchi, heart, oesophagus, stomach, intestine

–visceral motor - parasympathetic innervation muscle in bronchi, gut, heart

–somatic motor - to pharynx, larynx, palate & oesophagus

44
Q

What are the clinical applications of the vagus nerve?

A

–damage to pharyngeal branches cause difficulty in swallowing

–damage to laryngeal branches causes difficulty in speaking

45
Q

What is the pathway of the accessory nerve?

A

–small cranial (medulla) and large spinal roots exit via jugular foramen

46
Q

What are the components of the accessory nerve?

A

–somatic motor - striated muscle of soft palate, pharynx & larynx, and to sternocleidomastoid & trapezius

The vagus nerve also supplies somatic motor to the pharynx, larynx palate and oesophagus

47
Q

What is the clinical application of the accessory nerve?

A

Weakness in turning the head and shrugging the shoulder

48
Q

What is the pathway of the hypoglossal nerve?

A

–emerges from medulla and exits through the hypoglossal canal

49
Q

What are the components of the hypoglossal nerve?

A

–somatic motor - to muscles of tongue

50
Q

What is the clinical application of the hypoglossal nerve?

A

–vulnerable to damage during tonsillectomy

–causes paralysis & atrophy of ipsilateral half of tongue. Tip deviates towards affected side