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Brainstem 2 Flashcards

1
Q

Which part of the trigeminal nerve ganglia contains C-fibres (pain)?

Give 2 examples of where these can come from.

A
  • Spinal Nucleus (V)
  1. Larynx
  2. Oropharynx
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2
Q

At what level is the spinal nucleus of cranial nerve V?

A
  • Open Medulla
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3
Q

Which part is the open medulla & which is the closed medulla?

A
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4
Q

Which nerve carries somatosensory fibres from the pharynx?

A
  • Glossopharyngeal Nerve (9th cranial nerve)
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5
Q

How is the corticospinal tract presented in the brainstem?

A
  • Medulla –> aggregates into Pyramids
  • Pons –> broken down into Bundles
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6
Q

Name the structures present in the Open Medulla.

A
  • Inferior Cerebellar Peduncle
  • Spinal Nucleus of Trigeminal Nerve
  • Medial Lemniscus Pathway
  • Spinothalamic Pathway
  • Inferior Olives
  • Pyramids (corticospinal tract)
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7
Q

What does open medulla mean and is it the upper or lower part?

A
  • Open Medulla –> means the central canal has opened up into the 4th ventricle
  • It is the upper part of the medulla
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8
Q

Which part of the trigeminal nerve is found in the (upper) pons?

What type of somatosensation is usually found here?

A
  • Chief Sensory Nucleus (5th cranial nerve)
  • Discriminative Touch (large primary afferents)
  • A-betas

Example: Discriminative touch from the lips

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9
Q

What structures are found in the upper pons?

A
  • Superior Cerebellar Peduncle (suprisingly)
  • Chief sensory nucleus (of trigeminal nerve)
  • Spinothalamic Tract
  • Medial Lemniscus (dorsal nuclei is in medulla)
  • Corticospinal Bundles
  • 4th Ventricle (pons!)
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10
Q

What does PICA supply? (generally)

A
  • Dorsolateral Medulla
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11
Q

What does PICA stand for?

A
  • Posterior Inferior Cerebellar Artery
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12
Q

What does PICA supply? (specifically)

A

There are a lot of sensory effects

  • Spinal Trigeminal Nucleus (ipsilateral nociceptive analgesia)
  • Vestibular Nucleus (affects balance)
  • Spinothalamic Tract (contralateral nociceptive analgesia)
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13
Q

What does the dorso-lateral part of the medulla include?

A
  • Spinal Trigeminal Nucleus
  • Vestibular Nucleus
  • Spinothalamic Tract
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14
Q

What level does PICA supply?

A
  • Medulla
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15
Q

What are the presentations of a PICA lesion in the context of nociception?

A
  • Ipsilateral Loss of Nociception (& pain & light touch) of the Face (spinal nuclei V)
  • Contralateral Loss of Nociception (& pain & light touch) of the Body (spinothalamic tract)
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16
Q

What structures are found at the medlla level? (picture)

A
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17
Q

Where is the vestibular nuclei found? (what level?)

What does it do? (briefly)

A
  • Medulla
  • Affects Balance
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18
Q

What 2 things do visceral afferent fibres carry?

Give examples.

A
  1. Taste Afferents
  2. General Visceral Afferents

Carotid Sinus & Body

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19
Q

What is the nucleus with a hole in the middle called?

A
  • Nucleus of the Solitary Tract (NST)
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20
Q

Where do visceral afferent fibres all end up?

A
  • Nucleus of the Solitary Tract
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21
Q

Where do vestibular & cochlear (special sense) fibres end up?

A
  • Vestibular Nuclei
  • Cochlear Nuclei
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22
Q

What afferent fibres does the nucleus of the solitary tract (NST) receive?

What is it an important centre for (2 things)?

A
  • Visceral Afferents (taste & general visceral afferents)
  1. Centre for Autonomic Control
  2. Parts of it forms –> Dorsal Inspiratory Respiratory Centre
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23
Q

What nucleus is involves with ANS reflexes such as HR & BP?

A
  • Nucleus of the Solitary Tract
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24
Q

Where do baroreceptors & chemoreceptors sent their afferents to?

NB: From the carotid sinus & carotid body)

A
  • Nucleus of the Solitary Tract
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25
Q

If you interfered with the NST, what effects would you cause?

A
  • Heart Rate
  • Blood Pressure
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26
Q

What 2 nuclei is the Nucleus of the Solitary Tract (NST) connected to?

A
  1. Raphe Nuclei
  2. Locus Ceruleus
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27
Q

What does the Raphe Nuclei release?

A

5HT (Seratonin)

NB: Lowermost nuclei is in the medulla

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28
Q

What does the Locus Ceruleus release?

A
  • Noraadrenaline (NA)

This has a bigger effect in terms of analgesia than 5-HT

Nuclei is found on the floor of the 4th ventricle

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29
Q

Name 2 monoamines.

A
  • 5-HT (seratonin)
  • Noradrenaline (NA)
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30
Q

How does vagal stimulation help epilepsy?

A
  • Reduces Fitting

The nucleus of the solitary tract (ANS centre) is connected to:

  1. Raphe Nuclei (5HT)
  2. Locus Ceruleus (NA)

These when stimulated by NST release their monoamines which reduce fitting

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31
Q

Other than epilepsy, what can vagal stimulation help with?

A
  • Motor Recovery after stroke
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32
Q

Where do motor axons in cranial nerves arise from?

A
  • Motor Nuclei
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33
Q

What does the hypoglossal nucleus/nerve innervate?

How can we test this cranial nerve?

A
  • Tongue Muscle
  • Tested by asking patient to stick out their tongue
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34
Q

Where are all somatic motor nuclei found near?

A
  • Near the Midline
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35
Q

Where is the hypoglossal Nucleus found?

What is it beneath?

A
  • Floor fo the 4th Ventricle
  • Upper Part of the Medulla (open)
  • Foudn beneath the locus cereleus (which is slightly above)
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36
Q

What is the clinical presentation for someone who has a lesion in their hypoglossal nerve/nucleus?

What cranial nerve number is this?

A
  • Test: Stick tongue out
  • Tongue will deviate to side with lesion
  • Found close to midline
  • Cranial Nerve 12
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37
Q

What is the route of the hypoglossal nerve from inside the brainstem to outside?

A
  • Axons move anteriorly at the upper medulla level
  • Leave just lateral to corticospinal pyramids
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38
Q

Where is the dorsal nucleus of the vagus (X) nerve found?

What fibres does it send out?

Where do they go?

A
  • Dorsal Side of the Open Medulla
  • Just Lateral to the Hypoglossal Nucleus (supplying tongue)
  • Sends out parasympathetic fibres
  • Supplies a lot of the Viscera (thorax & abdomen) but also neck
    *
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39
Q

What does the nucleus ambiguus supply?

Motor or sensory?

A
  • Motor Nucleus

Supplies:

  • Muscles of the Pharynx
  • Muscles of the Larynx
  • Soft-Palate

These are all brachial muscles –> which are derived from pharyngeal (brachial) arches during development

They are all essential for speech & swallowing

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40
Q

What do the muscles of the pharynx, larynx and soft palate have in common?

A
  • They are all Brachial Muscles which are derived from the 4th & 6th pharyngeal arch musculature
    *
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41
Q

What fibres are found in the Vagus (X) Nerve?

A
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42
Q

The nucleus ambiguus allows for safe….

A
  • Speech

If you have a damaged nucleus –> foreign bodies can go down airway –> causing pneumonia (can kill)

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43
Q

What do cells in the nucleus ambiguus and around it form and supply?

A
  • Forms Ventral Respiratory Centre
  • Supplies heart

NB: Some axons from it join the vagus nerve & cranial accessory nerves

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44
Q

What is the mneumonic for remebering eye muscles innervation?

A

LR6 SO4 3

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45
Q

Where abouts are the following located?

  • Level?
  • Position?
  • Dorsal Nucleus of Vagus Nerve (X)
  • Nucleus Ambiguus
A
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46
Q

What does the abducens nerve (6th cranial nerve) supply?

A
  • Lateral Rectus
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47
Q

Where is the abducens nucleus?

A
  • Pons
  • Near Floor of 4th Ventricle
    *
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48
Q

What happens in left abducens palsy?

A
  • Patient cannot look to the left hand-side (right eye works but left does not)
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49
Q

What commonly affects the abducens nerve?

(What cranial nerve number is it?)

A
  • Any problems affecting the skull
  • It is a thread-like nerve
  • Cranial Nerve 6
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50
Q

What is Bell’s palsy?

A
  • Loss of muscle control on one side of the face
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51
Q

What do axons of the facial motor nucleus do that is unusual?

A
  • They loop around the abducens nucleus
  • They then exit the brain stem through the front side

This is due to embryology

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52
Q

What pharyngeal arch musculature does the facial motor nucleus supply?

A
  • 2nd pharyngeal arch (important in facial expression)
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53
Q

What does the facial nerve supply? (2 things)

(what cranial number is it?)

A
  • Muscles of Facial Expression
  • Stapedius (ear)
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54
Q

What is facial palsy?

A

Same as Bell’s Palsy

Loss of muscle control on one side of the face

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55
Q

What can cause Bell’s palsy?

A
  • Can be due to herpes virus (unkown for certain)
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56
Q

How can we test the facial motor nucleus?

A
  • Ask patient to –> Smile or Screw Up Eyes or Frown
  • Check for Symmetry

NB: Beauty is derived from symmetry

Photo shows patient can only smile on one side

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57
Q

Which part of the trigeminal nucleus is found at the rostral part of the pons?

A
  • Chief Sensory Nucleus (V) (usually just does discriminative touch of the face)
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58
Q

What does the motor nucleus of the trigeminal nerve supply?

A
  • Muscles of Mastication
  • Tensor Muscles (Ear)

These are the 1st pharyngeal arch musles

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59
Q

How do you test the motor nucleus of the trigeminal nerve?

A
  • Ask patient to clench their teeth
  • Feel the masseter / temporalis contracting on either side
  • Symmetry is important!
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60
Q

Which pharyngeal arch musculature does the motor nucleus of the trigeminal nerve supply?

A
  • 1st pharyngeal arch
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61
Q

Label this image of the midbrain.

A
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62
Q

What are the 2 parts of the oculomotor nucleus?

A
  1. Somatic Motor Nucleus Part
  2. Edinger-Westphal Nucleus (parasympathetic part)
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63
Q

What are the 2 functions of the oculomotor nerve?

(Which cranial nerve?)

A
  • Somatic Motor Part –> supplies somatic muscles of the eye
  • Parasympathetic Part (edinger-westphal) –> controls dilation of the pupils (constrictor papillae)
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64
Q

Is the optic nerve involved in the light reflex?

A
  • Yes
  • It is needed for the detection of light (afferent pathway)
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65
Q

How can we simultaneously test the optic nerve & oculomotor nerve?

A
  • Light Reflex Test
  • Flash Light into Eye

Optic Nerve –> picks up light and sends it to edinger-westphal nucleus (parasympathetic part) –> then midbrain reflex occurs –> causing oculomotor nerve to adjust constrictor muscles in the eye

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66
Q

What is the light reflex pathway (generally)?

A
  • Optic Nerve –> DETECTS LIGHT
  • Edinger-Westphal Nucleus –> causes Oculomotor to –> PUPILLARY CONSTRICT
    *
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67
Q

What 2/3 ways can the light reflex present a problem?

A
  • One Side not responding at all
  • Both sides not responding at all
  • One side responding more than the other side (should be equal)
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68
Q

Where is the oculomotor nucleus found?

A
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69
Q

What is the afferent & efferent limb of the light reflex?

A
  • Afferent Limb –> Optic Nerve (2)
  • Efferent Limb –> Oculomotor Nerve (3)
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70
Q

Does the light reflex require visual cortex?

71
Q

Describe the light reflex pathway.

A
  1. Light goes into Eye
  2. Detected by Photoreceptors –> transmitted to ganglion cells in retina
  3. Goes down optic nerve to pretectal nucleus (top part of midbrain)
  4. Fibres go to Edinger-Westphal Nucleus on both sides
  5. Parasympathetic fibres from here go down oculomotor (3rd) nerve to ciliary ganglion
  6. Synapse in ganglion
  7. Post-ganglionic neurones go to constrictor pupillary muscles of the eye
  8. This causes constriction
72
Q

What is the role of the pretectal nucleus?

A
  • Send fibres to both edinger-westphal nuclei (parasympathetic) on either side
  • From here pre-ganglionic neurones leave to go to ciliary ganglion
  • These then synapse to post-ganglionic neurones
  • They innervate constrictor pupillary muscles
73
Q

What does the posterior cerebral artery supply in the midbrain?

A
  • Corticospinal Tract
  • Substantia Nigra
  • Oculomotor Fibre
74
Q

What is the route of the PCA around the midbrain?

A
  • It winds around the midbrain –> towards the back of the forebrain
75
Q

How is the oculomotor fibre lost via a PCA lesion?

A

This leaves the brainstem (pons) ventrally –> thus it passes through a section of the brainstem supplied by the Posterior Cerebral Artery –> therrefore it can be lesioned

76
Q

What are the effects of a PCA lesion?

A
  1. Lesioned Oculomotor Nerve –> therefore no parasympathetic supply (no dilation) + no eye movements
  2. Lesioned Corticospinal Tract –> Upper Motor Neurone Lesion affecting contralateral side
77
Q

What is the main overall function of the cerebellum?

A
  1. Coordinate Movements
  2. Balance
78
Q

What does the lateral hemisphere of the cerebellum coordinate?

A
  • Coordinates voluntary movements (especially upper limb)

NB: It does many other things too

79
Q

What is the anterior lobe of the cerebellum important for?

A
  • Important in walking
80
Q

What is the midline part of the cerebellum important for?

A
  • Important in balance

NB: Specifically the floculomotor lobe

81
Q

What is ataxia?

A

Uncoordinated movement

82
Q

What is the midline called?

A
  • Vermis (‘worm like’)
83
Q

Why is the tonsil clinically relevant?

A
  1. High Intracranial Pressure (ICP)
  2. Lumbar Puncture

These can cause the tonsils to try to escape down the foramen magnum

This is bad as medulla organises breathing

84
Q

What 2 things will cause the tonsils of the cerebellum to try to escape down the foramen magnum?

A
  1. High Intracranial Pressure (ICP)
  2. Lumbar Puncture
85
Q

Which part of the brainstem is breathing organised in?

86
Q

Summarise how the cerebellum allows for accurate movement.

A
  • Cerebellum –> coordinates movement
  • It influences motor areas of the cerebral cortex which primarily control movements
  • It does not control motor neurones itself
87
Q

What is intention tremor?

A
  • Occurs when cerebellum is not correcting the motor function from M1
88
Q

How does the body compensate for a problem in the cerebellum when doing movements?

A
  • Uses visual information to guide & correct movements
  • This is slow however as you have to correct mistakes that are being made (retrospectively)

NB: Usually the cerebellum corrects these errors in the cortex before they’re even made

89
Q

Via what does the cerebellum influence motor movements?

A
  • Thalamus
  • Cerebral Cortex
90
Q

What is ataxia a sign of?

A
  • That the cerebellum is not working properly
  • It is not coordinating movements like it should be
91
Q

If you can do accurate movement, what does this mean?

A
  • Relevant side of the cerebellum is in good function (ipsilateral)
92
Q

Where is the vermis, hemisphere and tonsil?

93
Q

What does the cerebellum look like from above?

94
Q

What are the different parts of the cerebellum (cortex)?

A
  • Hemisphere (largest part sticking out on either side)
  • Vermis (midline - looks like segmented worm)
  • Para-Vermal Region (alongside vermis)

Each of the different sections have different functions

95
Q

What is the cerebellar cortex?

A
  • Grey matter that is folded into folia
96
Q

Where is the Nodule?

Why is it important?

A
  • Important in Balancing
  • Can only be seen with a sagital section (from side)
  • It is very close to the 4th ventricle
97
Q

What are the 3 layers of the cerebellar cortex?

A
  • Molecular Layer (outside)
  • Purkinje Cells
  • Granule Cell Layer (inside)
98
Q

What are the only axons that leave the cerebellar cortex?

A
  • Purkinje Cell Axons
99
Q

Where do the axons and dendrites of the purkinje cells in the purkinje cell layer pass through?

A
  • Purkinje Cells –> found in the PURKINJE CELL LAYER
  • Dendrites –> go UP –> into the Molecular Layer
  • Axons –> go DOWN –> into the Granule Layer & Subcortical White Matter
100
Q

What is found in the molecular layer of the cerebellar cortex?

A
  • Dendrites of Purkinje Cells found
101
Q

What is found in the Purkinje cell layer of the cerebellar cortex?

A
  • Axons of Purkinje Cells
  • These go to the subcortical white matter
  • Single row of purkinje cells
102
Q

What is found in the granule cell layer of the cerebellar cortex?

A
  • Most common types of neurones in NS (10^12)
  • Deepest layer
  • They are very small
  • There are more nerones here than all the other neurones in the brain put together
103
Q

What is the only output from the cerebellar cortex?

A
  • Purkinje Cells
  • Their axons are the only outputs
  • Axons go to underlying white matter
  • These axons are inhibitory

PC axon passes through the granule cell layer into sub-cortical white matter

104
Q

Where are the deep nuclei in the cerebellum?

What do they do?

A
  • These deep nuclei (grey matter) are embedded in the cerebellum
  • They give rise to most of the axons that leave the cerebellum

There is sub-cortical white matter in each hemisphere –> however within the white matter there is more grey matter –> these are called the deep nuclei

105
Q

Where is the fastigial nucleus?

Where does it project to? (2 places)

A
  • Near the midline

Projects to (2) places:

  1. Vestibular Nuclei
  2. Reticular Formation
106
Q

Where is the dentate nucleus?

Where does it project to?

A
  • Toothy Shape (hence the name)
  • One in either hemisphere (just like fastigial nucleus)

Projects to the Thalamus

  • Influences the Motor Cortex via Thalamus
107
Q

Where is the fastigial & dentate nucleus located and where do they project to?

108
Q

Where does the processing occur in the cerebellum?

A
  • Cerebellar Cortex
109
Q

What cell types are the output axons from the cerebellar cortex and are they inhibitory or excitatory?

A
  • Purkinje Cell Axons
  • Inhibitory (-)
110
Q

What are the 2 types of afferent axons entering the cerebellum?

A
  1. Mossy Fibres
  2. Climbing Fibres
111
Q

Is the input into the cerebellar cortex excitatory or inhibitory?

A
  • Excitatory
112
Q

Where does the output of the Purkinje Cell synapse?

A
  • Deep Nuclei
  • Onto Efferent Axon leaving Cerebellum
113
Q

Where do incoming fibres into cerebellar cortex send collaterals to?

Are these excitatory or inhibitory?

A
  • Deep Nuclei
  • These are excitatory nuclei

Thus incoming signals send 2 branches:

  1. Excitatory axon to the cerebral cortex
  2. Excitatory collateral to the deep nuclei

Therefore the collateral to deep nuclei excites and output from cerebellum cortex is inhibitory (after processing)

114
Q

What forms the climbing fibres?

Where do they originate from?

A
  • Olivocerebellar Fibres
  • Originate only from inferior olivary nuclei
115
Q

Where is the principal inferior olivary nucleus found? (level?)

A
  • Open Medulla
  • Ventral Side
    *
116
Q

Where abouts is the bump formed by the inferior olive?

A
  • This is why it is called an olive
  • Found lateral to pyramids
117
Q

What does the inferior olivary nucleus give rise to?

A
  • Olivo-Cerebellar Fibres
  • Travel via Inferior Cerebellar Peduncle to Cerebellum
  • Forms the Climbing Fibres in Cerebellum

The inferior olivary nuclei is the only source of climbing fibres in the cerebellum

118
Q

What are the main sources of mossy fibres?

A
  • Pontocerebellar Fibres
  • These come from the pontine nuclei

NB: There are other nuclei which make mossy fibres (unlike climbing fibre which has 1 source)

119
Q

Where is the information originally from? (show the route)

A
  • Route: Cerebral Cortex –> Pons –> Cerebellum
  • Originally information comes from the Cerebral Cortex (widespread areas)
120
Q

From which part of the brainstem does the mossy fibres come from? (level)

A
  • Pons
  • They pass to the cerebellum via the Middle Cerebellar Peduncle
121
Q

How are the pontine nuclei distributed?

A
  • They are intermingled among the corticospinal tract bundles
122
Q

Generally describe how the cerebral cortex & cerebellum work together using mossy fibres.

A
  • Cerebral Cortex –> plans movements
  • Tells cerebellum what the movement is
  • Thus cerebellum knows what it is expected to coordinate
  • This is done via inputs from motor areas of cerebral cortex via pontine nuclei –> to the cerebellum
123
Q

Describe the path of the neurones from the pontine nuclei (mossy fibres).

A
  • Neurones of the Pontine Nuclei (found between corticospinal bundles)
  • These axons cross the midline
  • They go through middle cerebellar peduncle
  • Enter cerebellum into hemispheres and become mossy fibres

Note: Pontine nuclei is the main source but not the only source of mossy fibres

124
Q

How many climbing fibres does each purkinje cell have?

A
  • There is (1) Climbing Fibre per Purkinje Fibre
125
Q

What is the function of the climbing fibre?

A
  • When it fires it helps the purkinje cells
  • They give error signals to the cerebellar cortex
126
Q

What do excitatory inputs synapse with in the cerebellar cortex?

A
  • Lots of dendrites of the granule cells
127
Q

What do the mossy fibres synapse with?

Where do they come from?

A
  • Mainly pontine nuclei (which get fibres from cerebral cortex)
  • Synapse with granule cells
128
Q

Gives (3) examples of destinations from the outputs of the cerebellum.

A
  1. Thalamus
  2. Red Nucleus
  3. Vestibular Nuclei
129
Q

Where does the axons of granule cells go?

What do they synapse with?

A
  • Molecular Layer (outermost layer)
  • Axons run up & down the folio of the cortex
  • Make lots of excitatory synapses on the dendrites of purkinje cells
130
Q

Overall, describe the information pathway in the cerebellar cortex.

A
  1. Information flows in through the mossy fibres
  2. They synapse with the granule cells
  3. Information goes up the axons of these granule cells to the molecular layer
  4. Here there are lots of excitatory synapses with the purkinje cell dendrites
  5. Purkinje cell then sends out inhibitory synapses to the deep nuclei
131
Q

What do mossy fibres do as soon as they come into the cerebellum? (2 things)

A
  1. Send excitatory axon towards the cerebellar cortex to synapse with purkinje fibre dendrites in molecular layer
  2. Send an excitatory collateral to the deep nuclei
132
Q

What is the source of mossy fibres & climbing fibres in the cerebellum?

A
  • Mossy Fibres –> Pontine Nuclei
  • Climbing Fibres –> Inferior Olivary Nuclei
133
Q

What are the signs of cerebellar hemisphere (lateral part) lesions? (3 things)

A
  1. Intention Tremor
  2. Dysdiadochokinesia
  3. Speech Problems
134
Q

What is dysdiadochokinesia?

A
  • Cannot do rapid alternating movements
135
Q

Are the effects of a cerebellar hemisphere lesion contralateral or ipsilateral?

A
  • Ipsilateral
  • Symptoms are found on the same side as the lesion
136
Q

What is intention tremor?

How do you compensate?

A
  • Cerebellum is not able to correct errors in movements automatically
  • Corrected by vision by watching your upper limb doing the action and manually correcting it
137
Q

What is the cerebellum important for doing?

A
  • essential for executing smooth non-stereotypic movements
138
Q

How does the climbing fibre carry out its function?

A
  • May give off excitatory collateral to the deep nuclei
  • Each Purkinje Cell has 1 Climbing Fibre going up it
  • There is a massive excitatory synapse
  • Acts on a handful of purkinje cells (however climbing up each PC is just 1)

NB: PC have the highest concentration of calcium-buffering proteins of any neurones - due to the large excitatory synapses (calcium is toxic in large quantities)

Climbing Fibres –> Directly excite purkinje cells

Mossy Fibres –> end on granule cells –> which then excite purkinje cells (via dendrites)

139
Q

What do lesions in the anterior lobe (orange) cause in terms of symptoms? (1 thing)

Who is this common in?

A
  • Gait Ataxia (walking problem)
  • Common in Alcoholics
140
Q

Why is the effects of the cerebellar lesion ipsilateral?

A
  • Pathway from cerebellar cortex to motor neurones involves a double cross
  • Therefore effects are ipsilateral (same side)

Output from cerebellum crosses the midline to the thalamus then M1 –> which when it sends out corticospinal tract also crosses the midline at the lower medulla level

Therefore cerebellum influences motor control on the same side

141
Q

Which deep nuclei do purkinje fibres in the cerebellar hemisphere send their axons to?

A
  • Dentate

NB: Each part of the cortex sends axons to corresponding nuclei (dentate is furtherest out so this makes sense)

142
Q

Through what does the lateral cerebellum influence movements?

A
  • Thalamus
  • Motor Cortex (M1)
    Corticospinal Tract
143
Q

Which tracts is the fastigial nucleus involved in? (name 3)

A
  1. Vestibulospinal Tract
  2. Reticulospinal Tract
  3. Medial Longitudinal Fasiculus

NB: The floccular-nodular lobe will send axons first to the fastigial nucleus which then influences these 3 tracts

144
Q

Via what does the vestibulocerebellum influence the 3 tracts?

A
  • Fastigial Nucleus

Influencing motor control via 3 tracts

145
Q

What are the effects of a floccular-nodular lobe lesion?

A
  1. Truncal Ataxia
  2. Nystagmus
146
Q

How does the floccular-nodular lobe influence motor control, via what? (name 3)

A
  1. Vestibulospinal Tract
  2. Reticulospinal Tract
  3. Medial Longitudinal Fasciculus
147
Q

What commonly affects the floccular-nodular lesion?

A
  • Medulla Blastoma
  • Common Tumours in Children

They won’t be able to sit upright due to this part of the cerebellum

148
Q

What is the obvious sign of someone who has a lesion of floccular-nodular lobe?

A
  • Loss of Balance
  • Unable to sit/stand upright
149
Q

What is the floccular-nodular lobe?

A
  • Vestibular Part of the Cerebellum
  • Balance
  • It enables you to stay upright
150
Q

Where is the floccular-nodular lobe found? (roughly)

A
  • Behind Cerebellar Peduncle
151
Q

Which deep nuclei & lobe of the cerebellum is influences motor function in 3 tracts?

A
  • Fastigial Nuclei
  • Floccular-Nodular Lobe
152
Q

What is the floccular-nodular lobe important in?

A
  • Balance
  • Sitting/standing upright
153
Q

From where does the fastigial nucleus receive information and where does it send it to?

A
  • Receive from: Floccular-Nodular Lobe
  • Send axons to: Vestibular Nuclei & Reticular Formation & Medial Longitudinal Fasiculus
154
Q

What reflex is the medial longitudinal fasiculus involved in?

A
  • Vestibulo-Ocular Reflex
155
Q

Where is the medial longitudinal fasiculus found?

A
  • Near Midline
  • Along the Brainstem
156
Q

Which 4 nuclei is the medial longitudinal fasiculus connected to?

A
  • Oculomotor (3)
  • Trochlear (4)
  • Abducens (6)
  • Vestibulocochlear (8)
    *
157
Q

What is the main function of the medial longitudinal fasciculus?

A
  • To connect nuclei of nerves controlling eye movement (LR6SO43) with the vestibular nuclei (working with floccular-nodular lobe)
158
Q

Where is the vestibular nuclei found?

Which 2 parts of the ear does it link up to?

Which ganglia is it linked to?

What lobe is the vestibular nuclei linked up to?

A
  • Lateral Part of the Floor of the 4th Ventricle
  • Linked to Utricle & Saccule
  • Vestibular Ganglia
  • Floccular-Nodular Lobe
159
Q

What do the vestibulospinal tracts do? (generally)

Are they involuntary or voluntary?

A
  • Keep you upright
  • They are not involved in voluntary movement
160
Q

What is the symptom of a lesion above the vestibulospinal tract?

Why does this occur?

A
  • Decerebrate Rigidity
  • Vestibulospinal tract is normally subject to descending inhibitory influences –> thus causing rigidity if this inhibition is lost
161
Q

What is the location in terms of spinal cord white matter for the vestibulospinal tract?

A
  • Ventral Part of the Spinal Cord White Matter
162
Q

From which 2 places does the lateral vestibular nucleus receive information?

A
  1. Floccular-Nodular Lobe
  2. Vestibular Apparatus
163
Q

What is decerebrate rigidity?

A
  • When all the extensor muscles contract a lot
  • Due to loss of inhibition causing muscle overdrive so they all contract
164
Q

Where does the lesion have to occur for decerebrate rigidity to occur?

A
  • Above the Lateral Vestibular Nucleus
  • To the descending inhibitory influences which usually come from the forebrain
165
Q

Can you survive with no cerebellum?

166
Q

What does the reticular formation give rise to?

A
  • Reticulospinal Tracts (medial & lateral tracts)
167
Q

What is the reticulospinal tract important in?

A
  • Motor Pathways
168
Q

Where does the brainstem reticular formation receive information from?

What kind of information is this?

A
  • Cerebral Cortex
  • Sensory Information –> particularly nociception
169
Q

Which ascending tract may give collaterals to the reticular formation?

What is the reticular information important for?

A
  • Spinothalamic Tract
  • Reticular activating system to keep you alert
170
Q

What important centres can some reticular formation nuclei form?

A
  • Some nuclei form ‘respiratory centres’
171
Q

What monoamine does the raphe nuclei project all over the CNS?

A

5-HT

Raphe Nuclei found in the midline mainly (lowest is medulla)

172
Q

What is the reticular formation involved in?

A

Things you do not want to think about

  • Control of Breathing
  • Control of Heart Rate
  • Involuntary Movements
  • Alert System (keep you awake)
    *
173
Q

How can the reticular formation be helpful with a corticospinal tract lesion?

A
  • It can voluntarily control movements
  • You can move using your reticular-spinal axons
  • Axons from Cerebral Cortex synapse with reticular formation therefore they can influence the reticulospinal tract and help control movements
174
Q

Where is the reticular formation found?

A
  • Fills all the spaces between the other structures we talk about

NB: Nuclei are indicated

Neuroanatomy (7 decks)

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