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Neuro > Cranial nerves > Flashcards

Cranial nerves Flashcards

1
Q

Cranial nerve 1 name

A

Olfactory

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2
Q

Cranial nerve 1 anatomical coruse

A
  • Unique: only cranial nerve to attach directly to cerebrum
  • Anatomical course
    ◦ Olfactory epithelial nerve cell bodies leave via cribriform plate of ethmoidal bone
    ◦ Synapse in the olfactory bulb above cribriform plate from which mitral cells (2nd order) send axons in olfactor tract to the olfactory cortex
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3
Q

Cranial nerve 2 is called? Unique factor

A

Cranial nerve 2: OPTIC
* Unique: 1 million fibres + envagination of dicephalon

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4
Q

Cranial nerve 2 course

A

◦ Retinal ganglion cells give axons that lead to vision - exiting eyeball at the optic disc through the optic canal
‣ Meninges extend to this point and myelin from oligodendrocytes

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5
Q

Pupillary light reflex path

A

Pupillary light reflex
* Afferent: CN2
◦ Retina –> optic nerve –> optic chiasm –> optic tract –> lteral geniculate nucleus
* Communication via the midbrain
* Efferent: CN3
* A light is shone into the eye and the pupillary contrictor response is observed for

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6
Q

Cranial nerve 3 called?

A

Occulomotor

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7
Q

Cranial nerve 3 has 2 types of motor nerve fibres

A

Somatic motor
Visceral motor

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8
Q

What somatic motor supply does CN3 provide

A

◦ From midbrain CN3 nucleus through superior orbital fissure
◦ Motor supply to
‣ Superior rectus
‣ Inferior rectus
‣ Medial rectus
‣ Inferior oblique
‣ Levator palpebri superioris
‣ Proprioception for these

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9
Q

Where does CN3 originate and pass through

A

Midbrain
Superior orbital fissure

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10
Q

What visceral motor efferents come from CN3 - where do they originate? First syanpse? Provide innervation to? What is interesting about them?

A

◦ Pre-synpatic in Edinger Westfall nucleus of midbrain, post synaptic from ciliary ganglion (node post entry to eye socket) through superior orbital fissure –> PSNS innervation to sphincter pupillae constriction + ciliary body causing contractiona dn accomodation
◦ They are the most superficial fibres i.e. the first affected by compression

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11
Q

CN3 injury results in what movement

A

Down and out
Dilated pupil
Ptosis

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12
Q

Cranial nerve 4 has what unique feature

A

Longest intracranial path
From the posterior brain surface rather than anterior

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13
Q

CN4 path

A

Longest intracranial path

◦ Originates from dorsal mesencephalon and emerges from posteiror brain surface
◦ Enters dura on free edge of cerebellum tentorium and passes in the lateral wall of the cavernous sinus 
◦ Enters orbit through superior orbital fissure to inenrvate superior oblique (uses pulley/trochlear) to move eye down, and in (inferior/medial)
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14
Q

CN4 innervates

A

◦ Originates from dorsal mesencephalon and emerges from posteiror brain surface
◦ Enters dura on free edge of cerebellum tentorium and passes in the lateral wall of the cavernous sinus
◦ Enters orbit through superior orbital fissure to inenrvate superior oblique (uses pulley/trochlear) to move eye down, and in (inferior/medial)

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15
Q

Cn5 has 3 branches?

A

Opthalmic
maxillary
mandibular

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16
Q

Opthalmic branch of the CN5 has what function

A

Somatic sensory

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17
Q

Path of CNV1

A

◦ Path –> from trigeminal ganglion (lateral to cavernous sinus in a dural recess) –> recurrent meningeal branches and anterior meningeal branches –> through superior orbital fissure
‣ Anterior meningeal –> anterior cranial cavity
‣ Posterior ethmoidal nerve gives off recurrent meningeal branches to produce tentorial nerves (post falx cerebri) as welll as of tentorium cerebelli
‣ Continuing opthalmic nerve does sensation to:
* Cornea
* Skin of forehead
* Scalp
* Eyelids
* Mucosa of nasal cavity
* Paranasal cavities

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18
Q

Path and character of CNV2

A

◦ Somatic general sensory
◦ Path
‣ Meningeal branch of V2 to last aspect of anteiror cranial fossa as well as nervesto the middle meningeal artery
‣ Then passes through foramen rotundum to supply the sensation to skin of face over maxilla, upper lip, maxillary teeth, mucosa of nose, sinuses and palate

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19
Q

Mandibular CNV3 contains what 2 varieties of nerve

A

◦ Somatic general sensory and somatic branchial motor

20
Q

What path does CNV3 take out of the skull?

A

Foramen ovale

21
Q

What does the CNV3 take

A

‣ Afferent fibres to middle meningeal arteri
‣ Posteior lateral section of the posteiorr cranial fossa/midle cranial fossa - dura
‣ Mucosa of the anterior 2/3 of the tongue
‣ Floor of mouth
‣ Mandibular teeth
‣ Skin of lower lip
‣ Lower face
‣ Cheek
‣ Ear externally
‣ TMJ

Somtatic brachial motor to masseter

22
Q

Corneal branch afferent

A

Nasociliary branch of the opthalmic nerve of the trigeminal nerve

23
Q

Efferent of the corneal reflex

A

CN7
◦ When one eye is tested both should blink, when the opposite eye doesn’t blink a collateral facial nerve palsy may be the cause

24
Q

How do you obtain the stimulus for a corneal reflex

A
  • Touch the corneas with soft cotton wool or gauze and examine the eyes for blinking or withdrawal response –> touching the sclera is not sufficient, the cornea is required
    ◦ scratching the cornea with a corner of gauze
    ◦ Using a drop fo saline
25
Q

Abducens nerve course

A
  • Path
    ◦ Emerges between pons and medulla running intradurally through cavernous sinus to enter orbit via superior orbital fissure
  • Clinical
    ◦ Long intracranial course predisposing it to ICP effects, lesions of ICA within cavernous sinous, cavernous sinus septic thrombosis
26
Q

What 3 different varieties of nerves do the CN7 supply

A

Special sensory - anterior 2/3 of tongue and taste
SOmatic motor once out of stylomastoid foramen supply stapedius of middle ear, stylohyoid and posterior belly of digastric and mucsles of facial expression
Visceral motor to submandibular and sublingual glands

27
Q

What are the 5 branches of the facial nerve

A

Temporal
Zygomatic
Buccal
Mandibular
Cervical

28
Q

What is the PSNS ganglion for CN7

A

Pterygopalatine

29
Q

Name of CN8

A

◦ Vestibulocochlear

30
Q

How do you test vestibuloccular reflex? What senses the stimulus? Where is the brainstem communication?

A

◦ Cold water is sensed by hair cells of the ampulla to thinking the head has turned to the opposite side
◦ Cmmunication via vestibular nuclei, lower pontin tegmentum, upper pontine tegmentum, midbrain paramedian tegmentum and medial longitudinal fasciculus
◦ This involves large central brainstem regions overlapping with ascending arousal system

31
Q

Efferents to the vestibulooccular reflex? What communication is there between the brainstem regions

A
  • Efferent: CN 3, 4, 6
    ◦ Communication between effector sites is through the medial longitudinal fasciculus
32
Q

What effect does a ruptured eardrum have on the vestibuloocular reflex

A

Does not invalidate

33
Q

What position must the patient be in to test the vestibulocular reglex

A

Head 30 degrees to achieve horizontal semicirculat cnala in position to maximise response

34
Q

How much water do you use in the vestibuloocular response

A

50ml of ice cold water

35
Q

What eye movement is normal for the vestibuloocular response?

A

eyes should deviated TOWARDS the tested ear

36
Q

How do you perform the oculocephalic reflex?

A

Only testable in an unconscious patient
Rotate the heat to one direction and eyes should deviate in the opposite direction smoothyl and conjugate gaze

The same is tested bilaterally

The same with looking up anddown

This is the Dollls eye phenomenon

37
Q

CN9 functions 5

A

◦ Somatic (branchial) motor
‣ Stylopharyngeus for swallowing by elevating laryngex and some action of pharyngeal muscles
◦ Visceral motor (PSNS)
‣ Pre-synaptic nerve bodies in infeiror salivary nucleus with post synaptic in the otic ganglion providing PSNS supply to the parotid
◦ Visceral sensory
‣ Cells in superior ganglion provides
* Sensation from parotid
* Carotid body –> NTS
* Pharynx and middle ear - soft palate and posterior 1/3 sensation fo tongue
◦ Special sensory
‣ Infeiro gnalgion gives nerve cells bodies that produce taste to the posterior 1/3 of the tongue
◦ Somatic general sensory
‣ Cutaneous sensation to external ear

38
Q

What is the first split of the vagus nerve

A

Post exiting the jugular foramen splits into cranial, cervical, thoracic and abdominla branches

39
Q

Describe the afferent pathway of the gag reflex

A

◦ Mechano or chemoreceptors - in this case rapidly adapting stretch fibre sin the pharynx/trachea or slowly adapting stretch receptors invovled in the Hering-Bruer reflex are stimualted (C fibres would be mechanical and chemical). Sensory information travels through afferent pathway via vagus to medulla oblongata (nucleus tractus solitarius)

40
Q

Efferent limb of the gag reflex

A

phrenic nerve and innovation of the thoracic and abdomianl musculature therefore cannot be tested in a high cervical injury
◦ Diaphragm, laryngeal muscles, external intercostals and rectus abdominus

41
Q

Efferent pathway for the pupillary light reflex

A
  • Efferent: CN3 (oculomotor nerve) via ciliary ganglion and short ciliary nerves to pupillary constrictor (M3 receptor) muscles (and ciliary muscle via short ciliary nerve in the case of accomodation)
42
Q

Afferent pathway of the corneal reflex

A
  • Corneal touch with soft cotton wool/gauze or a drop of saline and examination for blinking or withdrawal (bilaterally)
  • Sensory: light touch receptors (corneal, not sclera) –> nasociliary branch of the opthalmic branch of the trigeminal nerve (V1 fibres afferent corneal)
  • Afferent: CN5 –> trigeminal ganglion ipsilaterally –> trigeminal sensory nucleus of the pons –> bilateral innervation of efferent structures through reticular formation to bilat VII nuclei
43
Q

Efferent corneal reflex

A
  • Efferent: CN7 bilaterally via internal acoustic meatus –> mastoid sinus and geniculate ganglion –> orbicularis oculi muscles (blink)
44
Q

Effector of oculocephalic reflex

A
  • Processor - Vestibular nuclei –> cross to abducens nucleus (CN6)
  • Efferent: CN 3, 6
    ◦ Communication between effector sites is through the medial longitudinal fasciculus
    ◦ Ipsilateral eye CN6 –> lateral rectus –> abduct
    ◦ Contralateral eye - CN3 –> medial rectus –> adduct
45
Q

What is the processor of the gag reflex centrallly

A
  • Processor - Medulla - nucleus tractus solitaris ipsilateral
46
Q

What is the processor of the cough reflex centrally

A
  • Processor - Medulla - nucleus tractus solitaris ipsilateral

Neuro (7 decks)

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