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Neuroanatomy > Cranial nerves > Flashcards

Cranial nerves Flashcards

1
Q

Cranial nerve 0

A

Nervus terminalis

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2
Q

Function of nervus terminalis

A

Lies alongside the olfactory bulb.

Serves as a conduit along which a population of neurones migrates from the olfactory placode into the pre-optic area and hypothalamus.

These neurones are essential for reproductive function in both sexes

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3
Q

Components of the nuclei for CNs innervating the extraocular muscles.

A

Contain both motor neurones and internuclear neurones, with axons that contact the motor neurons for muscles that move the opposite eye in the same direction.

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4
Q

Location of oculomotor nucleus

A

Periaquedctal grey matter of the midbrain, ventral to the aqueduct at the level of the superior colliculus.

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5
Q

Passage of oculomotor nerve fibres within the midbrain.

A

Myelinated axons from each nucleus curve ventrally through the tegmentum and emerge from the medial side of the cerebral peduncle in the interpeduncular fossa.

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6
Q

Passage of oculomotor fibres after leaving the midbrain

A

Pass in the subarachnoid space, the lateral wall of cavernous sinus and the SOF.

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7
Q

What happens to the oculomotor nerve in the orbit?

A

Superior divison:

SR, LPS

Inferior division:

MR, IR, IO, Ciliary ganglion via short ciliary nerves

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8
Q

Arrangement of motor units in the oculomotor nucleus

A

The motor neurones for individual muscles are localised in distinct subnuclei.

The small sizes of the motor units (6 muscle fibres supplied by one neurone) indicate the level of precision required for co-ordinated eye movement in binocular vision

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9
Q

Location of the EW nucleus?

A

Situated dorsal to the main oculomotor nucleus.

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10
Q

Function of the EW nucleus

A

Preganglionic parasympathetic

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11
Q

Passage of EW neurones

A

Accompany the other oculomotor neurones into the orbit where they terminate in the ciliary ganglion behind the eye.

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12
Q

How do post-ganglionic parasympathetic fibres of the EW reach their targets

A

Pass through the short ciliary nerves to the eyeball where they supply the sphincter pupllae muscle of the iris and ciliary muscle

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13
Q

Through which structure do oculomotor and EW fibres run in the tegmentum of the midbrain?

A

Pass through the red nucleus.

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14
Q

Location of the trochlear nucleus

A

Immediately caudal to the oculomotor nucleus at the level of the inferior colliculus.

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15
Q

Passage of the trochlear nerve fibres after leaving their nucleus.

A

Small bundles of fibres curve around the periaqueductal grey matter with a caudal slope and decussate in the superior medullary velum.

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16
Q

Where do trochlear nerve fibres leave the brainstem?

A

The only nerve to emerge from the dorsum.

The slender nerve emerges immediately caudal to the inferior colliculus.

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17
Q

Function of SO

A

Depress, inwardly rotate and abduct the eyeball.

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18
Q

Location of the abducens nerve

A

Situated beneath the facial colliculus in the pons in the floor of the fourth ventricle.

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19
Q

What is the relationship of the facial nerve to the abducens nucleus?

A

A bundle of facial nerve fibres known as the internal genu curves over the nucleus, contributing to the facial colliculus.

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20
Q

Passage of motor neurones of the abducens

A

Gives rise to axons that pass through the pons in a ventrocaudal direction, emerging from the brainstem at the junction of the pons and the pyramid.

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21
Q

Interneurons of the abducens

A

Axons cross into the contralateral MLF and travel rostrally to the oculomotor subnucleus that supplies the contralateral rectus muscle.

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22
Q

Saccadic eye movements

A

Quick movements of the eyes in altering direction of gaze

Fr. saccader- to jerk

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23
Q

Optokinetic movements

A

Frequent saccades, made when the image on the retina is continuously changing.

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24
Q

Vergence movements

A

Both eyes looking medially to look at a near object or laterally to look into the distance.

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25
Q

Vestibular eye movements

A

Those driven by sensory input from the vestibular apparatus of the inner ear.

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26
Q

Concomitant squint

A

Both eyes can move through a full range of positions. Not caused by paralysis or weakness of the muscles. If one eye is covered the other will be able to move through the full range.

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27
Q

Why does diplopia disappear overtime

A

Diplopia is caused by misalignment of the image on the fovea of each eye. Over time the brain suppresses the false image.

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28
Q

What are the two golden rules in the diagnosis of diplopia?

A

The separation of the images increases with the amount of movement in the direction of pull of the weak muscle.

The flase image is displaced in the direction of action of weakness (i.e. the outside image is from the weakned eye).

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29
Q

Droppin of upper eyelid.

Lateral strabismus caused by unopposed action of LR

Inability to direct the eye medially or vertically.

Dilation of the pupil due to unopposed action of the dilator pupillae muscle in the iris

A

CN3 palsy

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30
Q

What happens to the pupil and lens in CN3 palsy

A

The pupil no longer constricts either in response to an increase in light intensity nor accommodation.

The ciliary muscle does not contract to allow the lens to increase in thickness for focussing on near objects.

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31
Q

What is the first sign of CN3 compression and why?

A

Slowness of pupillary response to light.

Preganlionic parasympathetic fibres run on the external surface of the oculomotor nerve.

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32
Q

Vertical diplopia maximal when eye directed downwards and inwards

Difficulty walking down stairs

A

Due to SO weakness

CN4 palsy

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33
Q

Causes of CN IV palsy

A

Peripheral neuropathy e.g. DM

A persistent complication of head injury

Tiny vascular lesions in the midbrain may be the most common cause of isolated non-traumatic oculomotor and trochlear palsies in the elderly

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34
Q

Medial squint with the inability to direct affected eye laterally.

A

CN VI palsy

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35
Q

The manifestation of CN VI nuclear damage

A

LR and contralateral MR paralysis.

The patient cannot direct gaze to the side of the lesion.

A nuclear lesion may also involve the nearby nucleus or axons of the facial nerve (remember close relation to internal genu) causing paralysis of all the ipsilateral facial muscles.

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36
Q

Which portion of the cortex controls voluntary eye movements

A

Frontal eye field

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37
Q

Location of frontal eye field

A

Anterior to general motor cortex

Brodman’s area 8

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38
Q

Consequence of stimulation of the frontal eye field

A

Conjugate deviation of the eyes to the opposite side.

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39
Q

Regions involved in voluntary eye movements

A

Prefrontal cortex

FEF

Superior colliculus

Extraocular CN nuclei.

Various areas of brainstem (pretectal, superior colliculus, PPRF, nucleus prepositus hypoglossi, rostral interstitial nucleus of the MLF, interstitial nucleus of Cajal). These regions are involved in maintiang the position of the eyes, genrating saccades and determining whether the eyes will move in the horizontal or vertical plane

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40
Q

What is the function of the paramedian pontine reticular formation

A

Centre for lateral gaze

Receives afferents from the contralateral cerebral cortex, contralateral superior colliculus and ipsilateral vestibular nuclei.

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41
Q

Action of the PPRF?

A

Sends bursts of impulses to the motor and internuclear neurones causing rapid contraction of the lateral rectus and contralateral medial rectus.

Slower tonic stimulation of the ocular motor neurones comes from the nucleus propositus hypoglossi which is rostral to the hypoglossal nucleus in the medulla.

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42
Q

Control of visual fixation

A

Slow eye movements

Posterior parietal eye field, adjacent to the visual association cortex of the lateral aspect of the occipital lobe.

Neural circuity involves the cerebellum and vestibular nuclei.

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43
Q

Neural pathways for convergence

A

Similar to those of visual fixation.
Requires the integrity of the occipital cortex but not that of the PPRF or the frontal eye field.

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44
Q

Afferent limb of pupillary response to light

A

Retina

Optic nerve

Olivary pretectal nucleus (in the pretectal area)

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45
Q

Efferent limb of pupillary light reflex

A

Fibres project from pretectal nucleus to EW.

Some pretectal neurones send their axons across the midline in the posterior commissure to the contralateral EW nucleus.

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46
Q

What are the reasons for consensual light reflex?

A

Each optic tract contains fibres from both retinas

The pretectal area projects to both sides.

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47
Q

Afferent limb of accommodation

A

Triggered by signals that originate in the retina and in the occipital cortex that are relayed through the superior colliculus to the EW nucleus

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48
Q

Efferent limb of accommodation reflex?

A

EW nucleus to the ciliary ganglion.

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49
Q

Action of the ciliary muscle?

A

On contraction allows the lens to increase in thickness and increases the refractive power

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50
Q

Action of sphincter pupillae

A

Sharpens the image by decreasing the diameter of the pupil and reducing spherical aberration in the refractive media of the eye.

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51
Q

Consequence of destruction of the frontal eye field?

A

Causes deviation of both eyes towards the side of the lesion.

Voluntary saccadic movements of the eyes away from the side of the cortical lesion cannot be made.

Commonly caused by ischaemic damage which is associated with damage to the premotor and motor areas due to its close relation.

Consequent paralysis of the limbs and lower half of the face on the contralateral side with the deviated eyes looking away from the paralysed side of the body.

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52
Q

What is the impact of a destructive lesion of the posterior parietal lobe on eye movements?

A

Impair the ability to make smooth pursuit movements away from the side of the lesion.
Voluntary saccades are unaffected.

The attempt to puruse a target in the visual field becomes a series of small, rapid movements of the eyes.

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53
Q

Foville’s syndrome

A

Caused by a dorsally located infarction in the caudal part of the pons, compromises ipsilateral nuclear CN6 an LMN facial palsy with contralateral hemiplegia and conjugate gaze palsy.

The limb paralysis recovers because most of the descending motor fibres are ventral to the infarct.

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54
Q

What is the difference between a nuclear and a nerve CN6 lesion?

A

Nerve- loss of LR

Nuclear- loss of LR and contralateral MR due to involvement of fibres to the MLF or the MLF itself

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55
Q

Internuclear ophthalmoplegia

A

Caused by a lesion inthe MLF (usually demyelination).

Interruption of the fibres going from abducens of the opposite to the oculomotor nucleus of the same side causes an inability to adduct the eye on the side of the lesion.

There will also be nystagmus of the abducting eye.

These abnormalities are present only when the patient is asked to gaze to the side opposite to that of the lesion.

Normal medial rectus function with convergence.

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56
Q

Where is the lesion in INO if the right eye cannot adduct.

A

Right sided MLF lesion.

Would expect the left eye to be able to abduct and there to be nystagmus.

https://www.youtube.com/watch?v=_rXQmDZva8Y

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57
Q

Destruction of the PPRF

A

Prevents saccadic contractions of the LR and the contralateral medial rectus muscles.

Pursuit and vergence movemnts are preserved.

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58
Q

Causes of paralysis of vertical gaze

A

Caused by lesion in the rostral midbrain.

Pressure from nearby tumour

Isolated lesions of various diseases

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59
Q

Parinaud’s syndrome

A

Pineal gland tumour compressing the posterior commissure and nearby structures causes paralysis of upward gaze

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60
Q

Compression of which structure causes paralysis of vertical gaze?

A

Posterior commisssure in the rostral midbrain.

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61
Q

Marcus Gunn Pupil

A

Paradoxical dilatation of the pupil on swinging light test.

Seen particularly in patients with optic neuritis.

No pupillary reflexes can be elicited by light shone into an eye that is blind for any reason.

https://www.youtube.com/watch?v=WrNYqNH3b3A

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62
Q

What is the most common cause of impaired pupillary light reflex?

A

Head injury.

Compression of the oculomotor nerve by the uncus which is forced over the free edge of the tentorium cerebelli as a result of raised ICP.

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63
Q

Aneurysms of which vessels can cause CN3 palsy

A

PComm

PCA

SCA

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64
Q

Holmes Adie pupil

A

Responds more slowly than the other pupil to both light and accommodation

Attributed to the death of neurones in the ciliary ganglion.

May be associated with sluggish stretch reflexes throughout the body (Holmes Adie Syndrome)

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65
Q

Argyll Robertson pupil

A

Accommodates

Does not react to light.

Pupil typically smaller and irregular.

Associated with CNS syphillis.

https://www.youtube.com/watch?v=IbBYxGk1pUw

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66
Q

Classification of cranial nerve pathways

A

Supranuclear (above brainstem)

Nuclear (brainstem)

Infranuclear (fascicle/nerve)

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67
Q

Common pathway for horizontal and vertical gaze pathway

A

PPRF/ CNVI

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68
Q

Location of vertical gaze centre

A

Thalamomesencephalic junction

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69
Q

Location of horizontal gaze centre

A

Pons

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70
Q

Supranuclear input on gaze pathways.

A

FEF- contralateral saccades

Parieto-occipitotemporal- ipsilateral smooth pursuit

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71
Q

How to differentiate between a supranuclear gaze palsy and a nuclear gaze palsy

A

In a supranuclear gaze palsy the VOR will be intact i.e. Doll’s head

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72
Q

Why is upgaze palsy more common than downgaze palsy

A

Upgaze is unilateral and crosses at the level of the posterior commissure where it is vulnerable to compression or damage by a single lesion (e.g. by pineal body tumour)

Downgaze is bilateral so later

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73
Q

1.5 syndrome

A

Horizontal gaze palsy (PPRF/VI)

+

INO (MLF)

One eye will have no horizontal movement (loss of abduction due to PPRF/VI lesion, loss of adduction due to MLF involvement)

Contralateral eye will have loss of adduction only (no contralateral signal)

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74
Q

Subarachnoid course of CN6

What is the significance of this?

A

Exits the root exit zone of the pons where it is tethered and ascends the clivus, turns 90 degrees at the superior aspect of the pons at the petroclinoid ligament.

Means that anything causing increased ICP affecting this subarachnoid portion will cause false localising sign.

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75
Q

In which portion of the cavernous sinus does CN6 lie

A

In the substance, in contrast to the other CN which lie in the wall

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76
Q

What are the 6 CN6 syndromes?

A

Nuclear

Fascicle

Subarachnoid portion i.e. false localising

Clivus syndrome from meningioma

Cavernous sinus syndrome

SOF syndrome

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77
Q

Raymond syndrome

A

Ventral pontine syndrome

Ipsilateral LR paresis due to CNVI involvement

Contralateral hemiplegia sparing the face due to pyramid tract involvement

CN6 fascicle involved

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78
Q

Etymology of clivus

A

Means slope

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79
Q

Millard Gubler Syndrome

A

Ventral pontine syndrome

Basis pontis and fsacicles of CN VI and VII affected.

Contralateral hemiplegia sparing the face due to pyramidal tract involvement

Ipsilateral LR palsy, accentuated when the the patient looks towards the lesion.

Ipsilateral peripheral facial paresis due to CN VII involvement

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80
Q

Why is the trigeminal so named?

A

Because it branches intracranially into three divisions

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81
Q

Where are the cell bodies of most of the primary sensory neurones of the trigeminal located?

A

Trigeminal ganglion in Meckel’s cave

The remainder are located in the mesencephalic trigeminal nucleus.

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82
Q

Extent of the sensory innervation of the trigeminal

A

Skin of the face and forehead, scalp as far back as the vertex of the forehead

Mucosa of the oral and nasal cavities and paranasal sinuses and the teeth.

Also innervates most of the dura and the cerebral arteries

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83
Q

Where do the central processes of the trigeminal ganglion cells terminate?

A

In the pontine and spinal ncueli.

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84
Q

Location of the pontine trigeminal nucleus?

A

(AKa chief, principal, or superior sensory nucleus)

Located in the dorsolateral area of the tegmentum at the level of entry of the sensory axons.

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85
Q

Components of the trigeminal nucleus?

A

Mesencephalic nucleus

Pontine trigeminal nucleus (principle nucleus)

Spinal trigeminal nucleus

Motor nucleus

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86
Q

Parts of the spinal trigeminal nucleus?

A

Pars oralis

Pars interpolaris

Pars caudalis

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87
Q

Where do discriminative fibres for touch sensation from nerves in the trigeminal field terminate?

A

In the pontine trigeminal nucleus

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88
Q

What forms the spinal trigeminal tract?

A

Large numbers of sensory root fibres turn caudally on entering the pons.

Contains innervation for light touch, pain and temperature.

Form the spinal trigeminal tract.

It also acquires fibres from the facial, glossopharyngeal and vagus nerves.

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89
Q

Extent of the spinal trigeminal tract

A

Form the lower pons to the upper third cervical segment of the spinal cord where they intermingle with axons on the dorsolateral tract of Lissauer

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90
Q

Where do axons in the spinal trigeminal tract terminate?

A

In the subjacent spinal trigeminal nucleus

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91
Q

Extent of the spinal trigeminal nucleus

A

Pontine trigeminal nucleus to the caudal limit of the medulla where it blendswith the dorsal horn of the spinal grey matter

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92
Q

Extent of pars caudalis of the

A

Extends from the level of the pyramidal decussation to spinal segment C3

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93
Q

Modality received by pars caudalis

A

Pain and temperature

Ipsilateral for the head

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94
Q

Extent of the pars interpolaris

A

From the leel of the rostral third of the inferior olivary nucleus to the pyramidal decussation

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95
Q

Extent of the pars oralis of the spinal trigeminal nucleus

A

Extends from the pars interpolaris rostrally to the pontine trigeminal nucleus.

Involved in tactile stimulation

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96
Q

Corneal reflex

A

Afferent- ophthalmic branch of trigeminal

Terminates in the motor nucleus of facial

Efferent: facial . nerve

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97
Q

Normal corneal reflex

A

Bilateral closure of eyelid.

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98
Q

Sneezing reflex

A

Afferent- maxillary branch of trigmeinal

Motor nucleus of trigeminal and facial nerves, nucleus ambiguus and hypoglossal nucleus, phrenic nucleus and motor cells in the spinal cord.

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99
Q

What is the pathway from the pontine and spinal trigmeninal nuclei to the thalamus?

A

Cross ventral trigeminothalamic tract which ascnds close the medial lemnisucus.

Smaller number of fibres crosssed and uncrossed proceed fromt he pontine tigreminal nuclues to the thalamus in the dorsal tirgminothtalmic tract.

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100
Q

What is the trigeminal lemniscus?

A

Combined ventral and dorsal trgiminothalamic tract

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101
Q

Where do fibres of the trigeminal lemnsicus terminate?

A

Ventral posterior medial nucleus of the thalamus

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102
Q

What is unusual about the mesencephalic trigeminal nucleus?

A

Strand of large unipolar neurones extending from the pontine trigeminal nucleus of the midbrain.

Primary sensory neurones- the only to be within the CNS rather than ganglia

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103
Q

What is the mesencephalic tract

A

Myelinated axons of the primary sensory neurones from the mesncephalic nucleus

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104
Q

What is the principle function of neurones from the mesencephalic nucleus

A

Their fibres end in deep proprioceptive receptors adjacent to the teeth.

They run to the motor nucleus of the trigeminal.

Involved in the control of forces of the bite

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105
Q

Location of the trigeminal motor nucleus?

A

Medial to the pontine trigeminal nucleus

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106
Q

What are the muscles of mastication?

A

Temporalis

Masseter

Medial + lateral pterygoid

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107
Q

What are the additional muscles innervated by the motor nucleus of the trigeminal

A

Tensor veli palatani

Tensor tympani

Anterior belly of digastric

Mylohyoid.

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108
Q

How does the motor nucleus of the trigeminal nerve receive descending efferents from the cortex?

A

By way of the corticobulbar tract

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109
Q

Jaw reflex

A

Mandibular nerve

Mesnephalic and motor trigeminal nucleu

Back down the mandibular.

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110
Q

What is the jaw-opening reflex

A

Contractions of the masseter, temporalis and medial pterygoid muscles are inhibited as a result of painful pressure applied to teeth.

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111
Q

Action of the tensor tympani

A

Receives acoustic fibres from the superior olivary nucleus.

Reflex contraction checsk excessive movement of the tympanic membrane caused by loud sound

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112
Q

Pathophysiology of trigeminal neuraliga

A

Demyelination of neurones in the sensory root caused in most cases by pressure of a small aberrant artery.

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113
Q

Which branch of the trigeminal nerve is most frequently involved in trigeminal neuralgia?

A

Macxillary

Then mandibular

Then ophthalmic

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114
Q

To which side does the mandible deviate in atrophy of the muscles of vmastication

A

To the affected side becuase of the unopposed action of the contralateral pterygoid muscle which protrudes the jaw.

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115
Q

Cranial nerve fascile

A

Portion of cranial nerve fibres that are within the brainstem.

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116
Q

Sensory component of the facial nerve?

A

Taste anterior 2/3rds of the tongue

Cutaneous fibres to the external ear

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117
Q

Facial nerve is parasympathetic to which glands?

A

Lacrimal

Submandibular

Sublingual

Glands of nasal mucosa

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118
Q

Where do the sensory and parasympathetic components of the facial nerve arise?

A

Nervus intermedius which is located between the motor root and the vestibulocochlear nerve

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119
Q

WIth which pharyngeal arch is the mandibular branch of rigeminal associated?

A

First pharyngeal arch

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120
Q

With which pharyngeal arch is the facial nerve associated?

A

Second

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121
Q

Intracranial portion of the facial nerve

A

Divided into subarachnoid portion and then facial canal portion

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122
Q

Origin of the facial nerve

A

Motor portion from facial nerve nucleus in the pons

Sensory and parasympathetic from nervus intermedius

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123
Q

Where are the cell bodies for the afferent nerves of the facial nerve found?

A

Geniculate ganglion

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124
Q

Where are the cell bodies for the efferent nerves of the facial nerve found?

A

Facial motor nucleus

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125
Q

Where are the cell bodies for the parasympathetic efferent component of the facial nerve found?

A

Superior salivary nucleus

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126
Q

What nerve leaves the facial nerve in he facial canal at the level of the geniculate ganglion

A

Greater petrosal nerve

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127
Q

How does the chorda tympani leave the middle ear?

A

Through a tiny canal in hte tymapnic part o the temporal bone to the infratemporal fossa

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128
Q

What are the branches of the facial nerve within the facial canal

A

Greater petrosal

Nerve to stapedius

Chorda tympani

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129
Q

What is the sensory branch of the facial nerve just prior to exiting the stylomastoid foramen

A

Somatic afferent fibres which merge with the IX and X to supply a small portion of the concha

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130
Q

What are the motor branches of the facial nerve after it exits hte stylomastoid formaen (extracranial)

A

Posterior auricular

Branch to posterior belly of digastric

Branch to stylohyoid

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131
Q

What are the terminal branches of the facial nerve

A

Temporal

Zygomatic

Buccal

Marginal mandibular

Cervical

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132
Q

Where is the geniculate ganglion found?

A

In the petrous temporal bone

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133
Q

What is the relationship of the facial nerve to abduences

A

Facscile arises ventral to VI in the pons, passes dorsally around the abducens nucleus at the facial colliculus as the facial genu before passing ventrally again to leave the brainstem ventrally.

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134
Q

What happens to teh axons of geniculate ganglin cells carrying taste from the anterior 2/3rds of te tongue after entering the brainstem?

A

Enter the brainstem in the nervus intermedius and turn caudally in the solitary tract.

The facial nerve fibres in this fasciulus are joined more caudally by gustatory axons rfrom the GPA and X.

Fibres from all three soruces terminate in the solitary nucleus. A column of cells adjacent to and partly surrounding the tract.

Only the large celled rostral part of the solitary nucleus recieves taste fibres.

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135
Q

What is the function of the rostral nucleus of the solitary tract?

A

Receives taste receptors from VII, IX and X

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136
Q

What is the area postrema?

A

Region of the medulla that controls vomiting.

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137
Q

What happens to ascending fibres for taste?

A

Run rostrally in the ipsilateral central tegmental tract, through the midbrain and subthalamic region tom their site of termination in the VPN of the thalamus.

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138
Q

Which thalamic nucleus receives taste fibres?

A

Ventral posterior nucleus

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139
Q

Where is the cortical area for taste?

A

Adjacent to the general sensory area for the tongue and extends onto the insula and forward to the frontal operculum.

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140
Q

Location of the facial motor nucleus

A

Caudal one third of the ventrolateral part of the pontine tegmentum.

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141
Q

What is the name for the configuration of facial nerve fibres running around abduenes?

A

The internal genu of the facial nerve

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142
Q

What is the function of stapedius

A

Reflex contraction in response to loud sounds prevents excessive movement of the stapes

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143
Q

What afferents input onto the facial motor nucelus?

A

Tectobulbar fibres from the superior colliculus- closure of the eyelids in response to bright light

Fibres from the trigeminal ssensory nucleus- corneal reflex, sucking and chewing repsonsel

Fibres fromt he superior olivary nucleus (part of the auditory pathway)- permits reflex stapedius conraction

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144
Q

How do parasympathetic fibres to the lacrimal glands reach their destination?

A

Preganglionic pass into the greater petrosal nerve and terminate in the pterygopalatine ganglion.

Post gangionic reach the lacrimal gland via the zygomatic branch of the maxillary nerve.

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145
Q

How do preganglionic fibres get to the submandibular ganglion?

A

Leave the facial nerve in the chorda tympani and are carried in the lingual branch of V3

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146
Q

Corticobulbar afferents to the muscles supplied by the facial nerve?

A

Are crossed, except for those supplying frontalis and orbicularis oculi which receive both uncrossed and crossed fibres.

Contralateral voluntary paralysis of only the lower facial muscles is therefore only a feature of UMN lesions

147
Q

Forehead sparing right facial nerve weakness

A

Left UMN lesion

148
Q

Featuresn of Bell’s palsy

A

Ipsilateral paralysis of the face

Ageusia of the anterior 2/3rds of te gonue.

Hyperacusis

(dependent on where int he canal the nerve is affected)

149
Q

Ageusia

A

Loss of taste

150
Q
A
151
Q

Causs of multiple cranial nerve lesions

A

NP carcinoma

Chronic meningitis e.g. CA, haematological malignancy, TB, sarcoid

GBS (motor only)

Brainstem lesions

Arnold-Chirari

Trauma

Paget’s

Mononeuritis multiplex

152
Q

Common causes of CNIII lesion

A

Idiopathic

Trauma

153
Q

Central causes of CNIII lesion

A

Brainstem vascular lesions

Tumour

Demyleination

154
Q

Peripheral causes of CNIII palsy

A

Compressive:

PComm anuerysm

Tumour

Basal meningitis

Nasopharyngeal carcinoma or orbital lesions

Ischaemia or infarciton in GCA, DM

155
Q

complete ptosis (partial ptosis may occur with an incomplete lesion)

divergent strabismus (eye ‘down and out’)

dilated pupil

unreactive to direct light (the consensual reaction in the opposite normal eye is intact)

unreactive to accommodation.

A

CNIII

156
Q

How can CN4 lesions be ruled out in a patient with CN3 palsy?

A

Always try to exclude a fourth (trochlear) nerve lesion when a third nerve lesion is present.

Tilt the head to the same side as the lesion.

The affected eye will intort if the fourth nerve is intact (remember SIN-the superior oblique intorts the eye).

157
Q

Causes of CN IV palsy

A

Idiopathic

Trauma

Cerebral peduncle lesions

158
Q

Failure to intort the eye

The patient may walk around with his or her head tilted away from the lesion – that is, to the opposite shoulder (this allows the patient to maintain binocular vision)

A

CN IV

159
Q

Causes of bilatearl VI palsy

A

Trauma

Wernicke

Mononeuritis

Raised ICP

160
Q

Causes of unilateral CN VI palsy

A

idiopathic

trauma

central (e.g. vascular lesion or tumour)

peripheral (e.g. raised intracranial pressure or diabetes mellitus)

161
Q

Cause of central CN IX and X palsy?

A

Vascular lesions (e.g. Wallenberg’s)

Tumouir

Syringobulbia

MND

162
Q

Causes of peripheral CN IX X palsies

A

Aneurysms at base of skull

TUmours

Chronic meningitis

GBS

163
Q

Which way is the uvula drawn in a unilatearl CN X palsy?

A

Towards the normal side

164
Q

Cuases of unilateral CN XI palsy

A

trauma involving the neck or the base of the skull

poliomyelitis

basilar invagination (platybasia)

syringomyelia

tumours near the jugular foramen

165
Q

Bilateral causes of CN XI palsy

A

MND

Polio
GBS

166
Q

Causes of bilatearl CN XII palsy

A

Vascular

MND

Tumours

167
Q

Causes of central unilateral LMN CN XII palsy

A

Vascular

MND

Syrinrgobulbia

168
Q

Causes of peripheral unilateral CN XII palsy

A

Posterior fossa: aneuryssms or tumours, chronic meningitis, trauma

Tumours of lymphadenopathy

Arnold-Chiari malformation

169
Q

Why is there usually no deviation of the tongue with a unilateral UMN lesion of CN XII

A

The tongue like the upper forehead as bilateral UMN innervation

170
Q

What is the largest avascular organ in the body?

A

Intervertebral disc

171
Q

What is a zygapophyseal joint

A

Another name for spinal facet joint

172
Q

What is the most common dermatome syndrome seen with craniocervical disease

A

C2

173
Q

Where does the pyramidal decussation begin and where does it complete?

A

Just below the obex and is not completed until below the exit of the first ceerbical nerve root

174
Q

Which spinal tract is compromised in a foramen magnum tumour presenting with hand weakness?

A

Corticospinal tract

175
Q

What is the significance of an enlarged intervetrebral foramen on radiology?

A

May represent a tumour

176
Q

What ligament is important to divide for proper visulaisation of .a ventral spinal tumour after dural opening in a posterior approach?

A

Dentate ligament

177
Q

Hyoid bone cervical level

A

C3

178
Q

Thyroid cartilage cervical level

A

C4-5

179
Q

Cervical level cricoid

A

C6

180
Q

Perioral tingling and numbness in syringobulbia is due to compression of which tract?

A

Spinal trigeminal tract

181
Q

At what level is the line drawn from one scapula tip to another when the patient is positioned prone?

A

T7

182
Q

What is a possible neuranatomical reason why a dorsal rhiotomy may fail to relieve pain and why a dorsal root ganglionectomy may be more effective

A

There may be a few nociceptive fibres that come into the horn via the ventral honr to terminate on the superifical layers of the dorsal horn.

These aberrant fibres do not traverse dorsal root but do no synapse in DRG

183
Q

What is a dorsal rhizotomy?

A

Neurosurgical procedure that selectively destroys dorsal . erve roots

184
Q

Which ligament is the priamry restraint against atlantoaxial AP transolcation?

A

Transverse ligament

185
Q

What is the caudalis portion of the spinal trigeminal tract?

A

An extension of the dorsal root entry zone and substantia gelatinosa of the trigeminal system into the lower meudllary and high cervical regions

186
Q

What supplies sympathetic innervation to the arm?

A

T2 and 3 nerve roots

187
Q

What is the spinal homologoue of the spinal trigeminal nucleus?

A

Spinal dorsal horn

188
Q

What is the other name of the dosal ramus of the C1 nerve root?

A

Suboccipital nerve

189
Q

What innervates the cervi al disk?

A

Plexus formed by the sinuvertebral nerve dorsally and the cervical sympathetic trunk ventrally.

Nocicpetive information from cervical disks enters the trigeminothalamic tract in the upper cervical spine and may be a contributory factor in patietns with cervicogenic headaches

190
Q

Level of aortic bifurcation

A

L4

191
Q

Loss of sensation of the first dorsal webspace of the foot is indicative of injury to which nerve?

A

Deep peroneal

192
Q

Nerve root affected with loss of Achilles reflex?

A

S1

193
Q

What nerve roots mediate biceps reflex?

A

C5/6

194
Q

Which reflex is associated with L5 nerve root?

A

None

195
Q

Where do pain and temperature 1o neurones synpase in the spinal cord?

A

Small, finely myelinated axons with bodies in the DRG.

The afferents enter the cord at the dorsolateral tract (zone of Lissauer) and synapse in the substantia gelatinosa ( II)

196
Q

What are the radiographic findings in acute transverse myelitis?

A

Usually normal, possibly with increased T2 signal

197
Q

What is Pott’s?

A

Tuberculous vertebral osteomyelitis

198
Q

How does tuberculous osteomyelitis of the spine differ from other bacterial infections

A

Affects the vertebral body rather than the disks primarily.

199
Q

To which part of the brain are the olfactory nerves attached

A

Telencephalon of prosencephalon via olfactory bulbs.

200
Q

Olfactory system

A

Olfactory nerve-> olfactory bulb (telencephalon)-> olfactory tract-> olfactory stria-> temporal lobe (lateral stria) the olfactopry area (piriform cortex)

201
Q
A

Piriform cortex, over uncus of temporal lobe (inferomedial area)

Concerned with olfaction

202
Q

How many olfactory nerves are there?

A

15-20 pairs

203
Q

What are optic nerves?

A

Central tracts from the diencephalon

204
Q

Why should optic nerves be considered central processes rather than cranial nerves?

A

Lined by oligodendroglia rather than Schwann cells

Not affected by peripheral cranial nerve lesions but are affected by lesions affecting central areas e.g. MS

205
Q

Segments of the oculomotor nerve

A

In midbrain

Subarachnoid space

Cavernous sinus

SOF

Extracranial

206
Q

Passage of oculomotor somatomotor fibres

A

Originate in the anterolateral region of the periaqueductal grey matter at the level of the superior colliculus.

Fibres pass through the tegmentum of the midbrain, the red nucleus, medial aspect of the CN emerging from the medial surface of the cerebral peduncle at the oculomotor sulcus into the interpeduncular fossa.

207
Q

Passage of oculmotor visceromotor fibres

A

Originate from EW nucleus in the periaqueductal grey matter of the midbrain at the level of the superior colliculus. PNS fibres pass with the somatomotor fibres to emerge from the ventral surface of the midbrain.

208
Q

What happens to the oculomotor nerve as it exits the cavernous sinus ventrally?

A

Divides into superior and inferior divisions.

209
Q

With which division of the oculmotor nerve do PNS fibres run as it exits the cavernous sinus

A

With the inferior divsion

210
Q

What is the arrangement of cranial nerves in the cavernous sinus as they enter dorsally?

A

OTOM

211
Q

What happens to the arrangement of cranial nerves as the cavernous sinus is traversed?

A

3rd starts moving caudally.

4th and V1 start moving rostrally.

By the ventral surface of the cavernous sinus, the nasociliary branch of V1 is between the upper and lower branches of CN3

212
Q

Where within the oculomotor nerve do the parasympathetic fibres run

A

Superficially and superiorly.

213
Q

Division of the SOF

A

Divided into three parts by the annulus of Zimm

Outer

Middle

Medial

214
Q

How does the oculomotor enter the orbit?

A

Through the SOF, through the annulus of Zimm with superior and inferior parts with the interposed nasociliary branch of V1

215
Q

Which nerves pass through the annulus of Zimm?

A

3 (superior and inferior)

Nasociliary

6

216
Q

What structures pass through the lateral part of the SOF (lateral to the annulus)?

LFT

A

Lacrimal branch of V1

Frontal branch of V1

4

(From lateral to medial)

217
Q

What structures are supplied by the superior division of CN3?

A

SR

LPS

218
Q

What structures are supplied by the inferior branch of CN3?

A

MR

IR

IO

219
Q

With which branch of the lower branch of CN3 do the PNS fibres run?

A

Run with the branch to IO but deviate to ciliary ganglion which is laterally located between CN2 and lateral rectus

220
Q

What are the two components of LPS?

A

Voluntary and involuntary components (can somatically open eyes but kept open involuntarily)

221
Q

Where does CN3 obtain its sympathetic contribution?

A

From the carotid sympathetic plexus inside the cavernous sinus

222
Q

Sympathetic fibres travel with which division of oculomotor?

A

Upper division

223
Q

Structures supplied by the lower portion of CN3?

A

IO, IR, MR

PNS fibres travel with a branch to IO to supply ciliary ganglion

224
Q

How do post-ganglionic PNS fibres emerge from ciliary ganglion?

A

As short ciliary nerves and pass between the sclera and the choroid to ciliaris and constrictor pupillae

225
Q

External ophthalmoplegia=

A

Failure of somatic extraocular muscles e.g. CN3 palsy

226
Q

Internal ophthalmoplegia

A

Failure of PNS component of CN3

Characterised by:

Fixed and dilated pupil

Cycloplegia causing blurred vision and glare of light.

227
Q

Weber’s Syndrome

A

Ventral midbrain pathology

Damage to CN3 and cerebral crus in midbrain

Ipsilateral CN3 palsy

Contralateral hemiparesis

228
Q

Benedikt’s syndrome

A

Mdibrain tegmental pathology

Ipsilateral CN3 palsy (CN3 nucleus or fascicle)

Contralateral abnormal motor movements (tremor, athetosis, chorea- due to involvement of red nucleus/rubrospinal tract)

With the addition of:

Contralateral hemianaesthesia (due to involvement of medial lemniscus)

or

Contralateral hemiplegia (if involves corticospinal tract)

229
Q

Vascular territories of midbrain

A

Ventromedial surface supplied by paramedian branches of basilar

Ventrolateral perforating branches from the PCA

230
Q

Aetiology of cranial nerve palsies in meningitis?

A

Due to fibrin content of CSF causing compressive CN lesions.

231
Q

Relationship of CN4 to PCA/SCA

A

Inferior to PCA but superior to SCA

232
Q

Into what does the CN4 emerge from the back of the midbrain?

A

Superior medullary velum which has a ridge of white matter centrally known as the frenulum veli

233
Q

Why might you get a concomitant Horner’s syndrome in patients with cavernous sinus pathology?

A

Some of the sympathetics run with V1 and V2

234
Q

What differentiates between SOF pathology and orbital apex?

A

Orbital apex lesions involve an optic neuropathy (e.g. RAPD) as II is found there

May also be a proptosis, orbital signs

235
Q

Arrangement of structures in the SOF from superior to inferior

LFTSNIA

A

Lacrimal

Frontal

Trochlear

Superior branch of III

Nasocilliary

Inferior branch of III

Abducens

236
Q

What differentiates between SOF pathology and cavernous sinus lesions?

A

The cranial nerves have started to branch so there may be lesions of the individual nerve branches

237
Q

Action and location of the nucleus prepositus

A

Found in the caudal pons and upper medulla

Part of the horizontal gaze holding system

238
Q

Which three systems are involved in the vascularization of the cranial nerves?

A

Inferolateral trunk (ICA)

Middle meningeal system (ECA)

Ascending pharyngeal system (ECA)

239
Q

Which CNs are supplied by the ILS?

A

III

IV,

VI

V1

240
Q

Which CN are supplied by the MMS?

A

V2

V3

VII

241
Q

Dual arterial supply of VII?

A

Infrapetrous portion- stylomastoid artery and the MMS

242
Q

Nerves supplied by the ascending pharyngeal system

A

IX

X

XI

XII

243
Q

Syndrome of ILT

A

EOM involvement and V1

Difficult to demonstrate

244
Q

Branches of the ILT and their specific CN supplied

A

Superior/tentorial artery supplies III and IV

Anteromedial branch enters the orbit through the SOF and supplies III, IV, V1,

Anterolateral branch passes through the foramen rotundum and supplies V2

Posterior branch supplies the sensory and motor portions of V3 anastomosing with the cavernous branches of the accessory meningeal artery and middle meningeal artery

245
Q

Segmental blood suppl to CN3

A

Posterior perforated sometimes- single artery arising from basilar

Supracavernous region- artery of Bernasconi

Intracavernous region- ILT

246
Q

Posterior perforated area

CN3 vascular interruption

A

Isolated CN3 palsy

247
Q

Supracavernous region

CN3 vascular pathology presentation

A

III and IV

248
Q

Intracavernous region

CN3 vascular pathology

A

Usually will include III, IV, VI and V1

249
Q

Components of the middle meningeal system

A

Middle and accessory meningeal arteries

Both arise from the maxillary branch of the ECA

250
Q

Origin of the stylomastoid artery

A

Posterior auricular (50%) of cases and occipital (50%)

251
Q

Blood supply of CN VII in the facial canal

A

Petrous branch of the MMA after anastomosing with the AMNA

Inferior tympanic artery (ascending pharyngeal)

Stylomastoid artery

252
Q

Branches of the ascending pharyngeal artery/

A

Anterior purely pharyngeal branch

Middle tympanic branch

Posterior meningeal branch

253
Q

Which branch of the ascending pharyngeal supplies CN IX-XII

A

Posterior meningeal branch

254
Q

Branches of the neuromeningeal branch of the ascending pharyngeal

A

Rostrally to caudakl

Jugular

Hypoglossal

Musculospinal arteries

255
Q

Which CN are supplied by the jugular branch of the neuromeningeal ascending pharyngeal artery?

A

IX, X, XII in their transcranial portion

256
Q

Blood supply to hypoglossal

A

Hypoglossal branch of the neuromeningeal branch of the ascending pharyngeal

257
Q

Blood supply to CN XI

A

Dual vascularisation from the jugular and musculospinal branches of the neuromeningeal ascending pharyngeal artery.

258
Q

Contents of Dorello’s canal

A

CN VI and the interior petrosal sinus

259
Q

Light reflex impact:

Lesion of ipsilateral CN3

A

Loss of direct but not consensual response

260
Q

Light reflex impact:

Contralateral CN3 palsy

A

Preserved direct but loss of consensual response

261
Q

Light reflex impact:

Ipsilateral CNII lesion

A

Loss of direct and consensual resonse

262
Q

Light reflex impact:

Contralateral CN II lesion

A

Does not affect ipsilateral pupillary responses

263
Q

Possible levels for lesions of conjugate horizontal gaze

A

Supranuclear

Nuclear

Internuclear

264
Q

Which trigeminal fibres bypass the trigeminal ganglion

A

Proprioceptive fibres carried in V3 bypass the trigeminal ganglion and continue into the brainstem to synapse directly on the mesencephalic nucelus.

This nucleus may thus be considered a sensory ganglion hat has been displaced into the brainstem.

265
Q

Muscles innervated by V3

A

Muscles of mastication- masseter, temporal, medial and lateral pterygoid

Anterior belly of digastric

Tensor tympani

Tensor veli palatini

266
Q

Describe the corneal reflex arc

A

Afferent fibres from the ophthalmic branch of V that synapse on the trigeminal sensory nucleus

Efferent limb consists of somatic motor fibres that begin in the trigeminal sensory nucleus on the stimulated side, projecting bilaterally to CNVII nuclei and terminating on orbicularis oculi

267
Q

Loss of direct and consensual corneal response

A

Ipsilateral CN V lesion

268
Q

Loss of direct but not contralaetral conreal reflex

A

Ipsilateral CN VII lesion

269
Q

Passage of internal genu of the facial nerve

A

Fascicles project dorsomedially, looping around CNVI to form facial colliculus in the floor of the fourth then passing ventrolaterally to exit the brainstem at the pontomedullary junction.

270
Q

How do fibres from the intermediate nerve distribute

A

In two branches- the superficial petrosal nerve-> lacrimal gland via pterygopalatine

Chorda tympani-> submandibular ganglion

271
Q

Isolated unilateral facial paralysis involving forehead

A

CNVII lesion distal to stylomastoid foramen

272
Q

Unilateral facial paralysis with loss of taste in anterior two thirds of tongue, forehead involved

A

Lesions within facial cnala proximal to takeoff of chorda tympani

273
Q

Unilateral facial paralysis, loss of taste sensation and tinnitus/deafness with loss of tearing (forehead involved)

A

Lesions within IAM

274
Q
A
275
Q

Why do supranuclear facial palsies result in forehead sparing?

A

COritcobulbar fibres to supply the face provide contralateral innervation of the lower face but bilateral innervation of the upper face.

276
Q

What are the functional components of the glossopharyngeal nerve

A

Somatic motor to stylopharyngeus

Visceral motor to parotid gland via otic ganglion

Somatic sensory, cell bodies in inferior glossopharyngeal ganglion supply skin of external ear

Visceral sensoy, cell bodes in inferior glossopharyngeal ganglion and carry sensation from the posterior third of tongue, pharynx and eustachian tube as well s chemo and baro-receptive impulses from the carotid sinus and body terminating in the solitary tract nuclei

Special sensory, taste from posterior third of tongue

278
Q

What is the location of the cell bodies of the vagus nerve?

A

Superior and infeior ganglia which lie within the jugular fossa of the petrous temoral bone.

279
Q

Ipsilateral anosmia

Ipsilateral optic atrophy

Contralateral papliioedema

A

Foster Kennedy Syndrome

Olfactory groove or sphenoid wing meningioma

280
Q

UMN lesion of the hypoglossal

A

Tongue deviation to the contralateral side

281
Q

Pain in distribution of V1 and V2

Oculosympathetic paresis (ptiosis and miosis) with preservation of sweating.

+/- loss of sensation in V1/2

A

Raeder Paratrigeminal Syndrome

Usually due to middle cranial fossa lesions between the trigeminal ganglion and the ICA.

282
Q

Pain and sensory disturbance in V1 (due to impairment of ophthalmic nerve)

Ipsilateral lateral rectus palsy (due to abducens impairment)

A

Gradenigo’s syndrome

Usually due to inflammatory lesion at the apex of the petrous bone

May also include oculosympathetic paresis with preservation of facial sweating

283
Q

Pain and sensory disturbance in V1

Ipsilateral ophthalmoplegia

Proptosis

Conjunctival injection

A

Cavernous sinus syndrome

Oculosympathetic paresis with preservation of facial sweating may occur

284
Q

Pain and sensory disturbance in V1

Ipsilateral ophthalmoplegia

Not cavernous sinus syndrome

A

SOF syndrome

285
Q

Retro-orbital pain and sensory loss in V1

Ipsilateral ophthalmoplegia

Granulomatous lesion

A

Tolosa-Hunt Syndrome

Granulomatous lesion in the cavernous sinus

286
Q

Ipsilateral facial paralysis

Ipsilateral lateral rectus palsy

Contralateral hemiplegia

A

Millard-Gubler Syndrome

Due to ventral pontine lesion

287
Q

Ipsilateral facial paralysis

Paralysis of conjugate gaze to the side of the lesion (abducens and PPRF)

Contralateral hemiplegia

A

Foville’s Syndrome

288
Q

Progressive sensorineural hearing loss

Tinnitus

Vertigo

Unsteadiness

CN VII palsy

Facial pain and sensory loss with depressed corneal reflexes

A

CPA syndrome

289
Q

Symptomology of CPA syndrome

A

Vestibular schwannomas- early prominent hearing loss, late CNVII and trigeminal involvement, infrequent lower CN palsies

Meningiomas- early CN VII and trigeminal involvement, late haring loss and more common lower CN involvement

290
Q

Loss of taste in the posterior third of the tongue

Paralysis of VC, palate and anaesthesia of larynx/pharynx

Ipsilateral trapezius and SCM weakness

A

Vernet’s syndrome

Due to a lesion in the jugular foramen, most commonly a glomus jugulare tumour

291
Q
A
292
Q

Vagal ganglionic anatomy if not done

A
293
Q

Laterality of smooth pursuit

A

Ipsilateral (saccadic eye movements are contralateral)

294
Q

Retinal disparity

A

Disparirty between the location of images on the two retinas

295
Q

Retinal blur

A

Defocused images

296
Q

Stimuli to retinal vergence

A

Retinal blur which leads to accommodation linked vergence

Sense of nearness (proximal vergence)

Cues such as perspective and size (tonic verngence)

297
Q

What are the three levels of the accommodation reflex

A

Convergence

Accommodation of the lens

Pupillary constriction

298
Q

Accommodation of the lens

A

Involves contraction of the ciliary muscle

Reduces tension on the suspensory ligament of lens

Causes lens to become more spherical

299
Q

What differentiates between a posterioorly and centrally located INO

A

In a posteriorly located INO, vergence system is intact

In centrally located it is impaired

300
Q

Anatomy of vertical gaze movements

A

Originate bilaterally and pass to the pretectal area (vertical gaze centre)

Thence to CN3 and 6

301
Q

What are the two major vertical gaze palsies?

A

Parinaud’s

Steele-Richardson-Olszewski

302
Q

Steel-Ricahrdson-Olsweiski syndrome

A

Primary supranuclear palsy

Downward gaze palsy with nuchal rigidity and progressive dementia

(Parkinson plus syndrome)

303
Q

Which of the oculomotor subnuclei are crossed?

A

Superior rectus subnucleus supplies contralateral size

304
Q

Possible patterns of CN3 nuclear palsies

A

Complete CN3 ipsilateral plus bilateral ptosis and SR palsy

Bilateral ptosis with normal EOM (CCNN involved)

Bilateral CN3 palsy with lid sparing

https://youtu.be/3je8-2dz-GQ

305
Q

What is the significance of ptosis w.r.t nuclear CN 3?

A

There is a central caudate nucleus which provides bilateral innervation to the LPS.

If there is a nuclear CN3 lesion there is either bilateral ptosis (involvement of CCN) or no ptosis

306
Q

L down and out eye with bilateral ptosis and impaired upgaze in R eye

A

L nuclear CN3 palsy

Involvement of central caudal nucleus which provides bilateral innervation to LPS

R impaired upgaze is due to involvement of L SR subnucleus which is crossed

307
Q

L CN3 palsy with unilateral ptosis

A

By definition cannot be nuclear

308
Q

Isolated CN3 MR subnucleus lesion

A

Rare as medial rectus subnucleus is so large difficulty to knock it out in an isolated fashion

More likely to be an INO

309
Q

Pupil in nuclear CN3 palsy

A

Usually bilateral as EW in close proximity if nuclear lesion

310
Q

Cause of light-near dissociation in Parinaud’s

A

Involvement of pre-tectal nucleus impacting on light reflex

The near pathway has cortical projections

311
Q

Argyll-Robertson pupil basis

A

Neurosyphilis affecting pre-tectal pathway

312
Q

How to differentiate between CN3 palsy and EW lesion

A

Look for preservation of accommodation pathway

https://youtu.be/4FhYD0TndqU

313
Q

Bilateral ganglionic (ciliary) light near dissocisation

A

Can be post optic nerve sheath fenestration

HSV

HZV

DM autonomic ganglionopathy

Autoimmune

B/L Adie’s Tonic pupil

314
Q

N3 palsy

Optic atrophy

Proptosis

Isolated involvement of superior or inferior divisoin

A

Orbital lesion

315
Q

Most common CNIV lesion

A

Contusion of nerve in subarachnoid course against the edge of the tentorium, may be bilateral

316
Q

Parkinson’s Syndrome

CN6

A

Cavernous sinus lesion

6th nerve palsy with Horners

Sympathetic fibres join the 6th for a short period within the cavernous sinus

317
Q

Direction of nystagmus in peripheral destructive lesion

A

In a peripheral vestibular lesion, the fast phase of the nystagmus is usually directed away from the side of a destructive lesion

Left destructive lesion.

Unopposed right firing-> crossed to LPPRF, abduction so conjugate gaze towards left with corrective fast saccade to right

318
Q

Most common form of nystagmus seen in clinical practice

A

Drug indued

319
Q

Relaionship between barbiturates and eye movements

A

Intoxication will cause degeneration of smooth pursuit movements followed by saccadic eye movements

Sever barbiturate intoxication eliminates even caloric responses

Patient with intact pupillary light reflex but absent caloric may be in barbiturate coma

320
Q

Distinguishing physiologic end point nystagmus from pathological

A

Symmetrical

Absence of other associated neurological signs

321
Q

Pattern of gaze evoked nystagmus

A

Central cause

Bilateral horizontal gaze evoked nystagmus usually associated with nystagmus on upgaze

Rarely with down gaze nystagmus

322
Q

Gaze paretic nystagmus

A

Patient unable to sustain eccentric gaze

Eyes have tendency to wander towards the primary position with corrective saccadic movements to eccentric position

Most commonly caused by durg intoxication

323
Q

Spasmus nutans

A

Syndrome of infancy which typically spontaneously resolves

Triad of head nodding, nystagmus and head-turning.

Nystagmus is commonly monocular and variable

324
Q

Ocular bobbing is associated with

A

Massive pontine lesion

325
Q

Opsoclonus in younger children may represent

A

Remote effect of neuroblastoma

326
Q

Square wave jerks

A

Pairs of saccades that are directed away from and back to fixation

May be associated with cerebellar lesions

327
Q

Why is strictly upbeat nystagmus more likely to be central

A

Peripheral vestibular lesions tend to generate mixed waveforms, combinations of rotatory/horizontal/upbeat

328
Q

Upbeat nystagmus with normal MRI

A

Think Wernicke’s, paraneoplastic/autoimmune

329
Q

Difference between opsoclonus and ocular myoclonus

A

Opsoclonus is continued disorganised chaotic repetitive saccadic movements occuring in all direction

Ocular myoclonus is continuous rhythmic oscillation of the eyes

330
Q

Describe the passage of sympathetic innervation to pupil

A

Originates in posterolateral hypothalamus

First ordered descending sympathetic fibres passes through lateral tegmentum of brainstem to reach intermediolateral gray matter of C8-T2 (ciliospinal centre of budge)

Intermediolateral gray projects second-order neurone up the sympathetic chain to the superior cervical ganglion

Superior cervical ganglion sends third-order neurone via the ICA to CN6 then V1 via the long ciliary nerve to dilator pupillae

331
Q

What are the other sympathetic fibres that travel with the pupillodilator pathway

A

Sudomotor and vasomotor to the face via ECA

Second via the ICA then ophthalmic artery to orbit to the superior tarsal muscle which elevates the eyelid

332
Q

Location of ciliary ganglion

A

Temporal side of the ophthalmic artery between the optic nerve and lateral rectus

333
Q

How to test for pharmacological mydriasis

A

Instil 1% pilocarpine into the eye

In the normal person or with interruption of parasympathetic innervation, the pupil will constrict as the drug acts directly at the NMJ

If there is pharmacological blockade it will not constrict

334
Q

Traumatic mydriasis

A

Ocular trauma can result in transient loss of parasympathetic tone or via direct injury to the pupillary sphincter

Weak miotic will cause constriction in patient with loss of parasympathetic tone but not in pupillary sphincter injury

335
Q

Diagnostic test for Adie’s tonic pupil

A

Instillation of very weak miotic (0.125% pilocarpine)

This solution would not work in a normal person but in patients with a tonic pupil with ciliary dysfunction, there is parasympathetic supersensitivity which leads to pupillary constriction after instillation of weak mioitc agent.

336
Q

Hutchinson’s pupil

A

AKA surgical CN3 palsy

337
Q

Midrbain pupillary abnormaltiy

A

Light naer dissociation

Impairment in upgaze

338
Q

Classic structural lesion associated with pinpoint pupils

A

Pontine

339
Q

Pharmacological test for Horner’s syndrome

A

INstillation of 10% cocaine to block noradrenaline reuptake

In normal person, this causes pupillary dilatation

In Horner’s there is no dilatation as there is no accumulation of Norad

340
Q

How to distinguish Horner’s syndrome from simple anisocoria

A

Check pupillary light reflex, if both react then patient may have simple anisocoria

Turn the lights off- if the smaller pupil is abnormal then the anisocroia will become more pronounced, a dilatation lag of the smaller pupil implies poor sympathetic tone and suggests diagnosis of Horner’s

341
Q

Muscles involved in eye opening

A

LPS (CN3)

Superior tarsal muscle/Muller’s muscle that is embedded in the levator muscle and inserts on tarsal plate (sympathetic fibres)

Frontalis helps to retract eyelid in extreme upgaze (CN7)

342
Q

Explain Bell’s phenomenon

A

LPS and SR innervated by superior division of oculomotor

To coordinate simultaneous eyelid opening and upgaze the tone should remain equal.

During forced lid closure which is caused by contraction of orbicularis oculi muscle (CN7) rather than normal lid closure which is associated with loss of tone in LPS, the SR tone remains high causing elevation of the eye- Bell’s phenomenon

343
Q

Def: lid retraction

A

When there is sclear showing between eyelid and iris

344
Q

How to differentiate between lid retraciton in thyroid eye disease and midbrain syndrome

A

Dorsal midbrain syndrome is typically bilateral retraction

Light-near dissociation seen

No suggestion of led retraction on downrad gaze

345
Q

What is the most common cause of lower eyelid retraction

A

CN7 palsy

346
Q

Coria

A

Pupil

347
Q

Anisocoria in which bigger pupil is not reacting properly to light

A

Problem with bigger pupil- PNS

348
Q

Ansiocoria in which smaller pupil doesn’t dilate in dark

A

Issues with smaller pupil-> sympathetics

349
Q

How to test anisocoria is due to ciliary ganglion problem

A

Near reflex is preserved so there is light near dissociation

Low dose pilocarpine will cause constriction

350
Q

Right unilaterally dilated pupil

Which is worse in light

No features of CN3 palsy

Light near dissociation

Dilates with low dose pilocarpine

No structural abnormality

A

Adie’s tonic pupil

351
Q

Degree of ptosis in Horner’s

A

1-2mm

352
Q

Apraclonidine eye drop

A

Direct SNS

Alpha agonist with differential activity for alpha 1 and 2

Under normal conditions, alpha 2 predominates, so if put into normal pupil it will either stay the same size or get smaller

In denervated eye, alpha 1 predominates and it will cause dilatation

353
Q
A

Facial nerve

Stylomastoid artery highlighted- branch of posterior auricular artery and should be presreved as it supplies the facial nerve

Anastomoses with superficial petrosal branch of middle meningeal artery

354
Q
A

Greater superficial petrosal nerve

355
Q
A

Hypoglossal nerve coming through above occipital condyle

356
Q
A
357
Q
A

Vidian nerve

358
Q

Consequence of sacrificing vidian nerve

A

Dry eye

359
Q

Dry eye post trans-sphenoidal

A

Vidian nerve sacrific

360
Q
A
361
Q

What is this structure?

What is its innervation?

A

Tensor tympani

V3

362
Q

What is this structure?

What is it a branch of?

A

Greater petrosal nerve

VII

363
Q

What is this structure?

What is it passing underneath

A

VI

Passing under Grubner’s ligament

364
Q

What is this structure visualised via temporal craniotomy?

A

Greater petrosal nerve

365
Q

Why is there bilateral SR weakness in nuclear third nerve palsy?

A

SR is crossed but the crossing fibres pass in close proximity to the other subnuclei which means with nuclear 3rd nerve palsy the SR subnucleus and the crossing fibres are often both involved

Neuroanatomy (18 decks)

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