Brainstem 2 Flashcards
(174 cards)
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)
- Larynx
- Oropharynx
2
Q
At what level is the spinal nucleus of cranial nerve V?
A
- Open Medulla
3
Q
Which part is the open medulla & which is the closed medulla?
A
4
Q
Which nerve carries somatosensory fibres from the pharynx?
A
- Glossopharyngeal Nerve (9th cranial nerve)
5
Q
How is the corticospinal tract presented in the brainstem?
A
- Medulla –> aggregates into Pyramids
- Pons –> broken down into Bundles
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)
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
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
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!)
10
Q
What does PICA supply? (generally)
A
- Dorsolateral Medulla
11
Q
What does PICA stand for?
A
- Posterior Inferior Cerebellar Artery
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)
13
Q
What does the dorso-lateral part of the medulla include?
A
- Spinal Trigeminal Nucleus
- Vestibular Nucleus
- Spinothalamic Tract
14
Q
What level does PICA supply?
A
- Medulla
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)
16
Q
What structures are found at the medlla level? (picture)
A
17
Q
Where is the vestibular nuclei found? (what level?)
What does it do? (briefly)
A
- Medulla
- Affects Balance
18
Q
What 2 things do visceral afferent fibres carry?
Give examples.
A
- Taste Afferents
- General Visceral Afferents
Carotid Sinus & Body
19
Q
What is the nucleus with a hole in the middle called?
A
- Nucleus of the Solitary Tract (NST)
20
Q
Where do visceral afferent fibres all end up?
A
- Nucleus of the Solitary Tract
21
Q
Where do vestibular & cochlear (special sense) fibres end up?
A
- Vestibular Nuclei
- Cochlear Nuclei
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)
- Centre for Autonomic Control
- Parts of it forms –> Dorsal Inspiratory Respiratory Centre
23
Q
What nucleus is involves with ANS reflexes such as HR & BP?
A
- Nucleus of the Solitary Tract
24
Q
Where do baroreceptors & chemoreceptors sent their afferents to?
NB: From the carotid sinus & carotid body)
A
- Nucleus of the Solitary Tract
25
If you interfered with the NST, what effects would you cause?
* Heart Rate
* Blood Pressure
26
What **2 nuclei** is the **Nucleus of the Solitary Tract (NST)** connected to?
1. Raphe Nuclei
2. Locus Ceruleus
27
What does the Raphe Nuclei release?
5HT (Seratonin)
NB: Lowermost nuclei is in the medulla
28
What does the **Locus** **Ceruleus** release?
* Noraadrenaline (NA)
This has a bigger effect in terms of analgesia than 5-HT
Nuclei is found on the floor of the 4th ventricle
29
Name 2 monoamines.
* 5-HT (seratonin)
* Noradrenaline (NA)
30
How does vagal stimulation help epilepsy?
* **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**
31
Other than epilepsy, what can vagal stimulation help with?
* Motor Recovery after stroke
32
Where do motor axons in cranial nerves arise from?
* Motor Nuclei
33
What does the hypoglossal nucleus/nerve innervate?
How can we test this cranial nerve?
* **Tongue Muscle**
* Tested by asking patient to **stick out their tongue**
34
Where are all somatic motor nuclei found near?
* Near the Midline
35
Where is the hypoglossal Nucleus found?
What is it beneath?
* Floor fo the 4th Ventricle
* Upper Part of the Medulla (open)
* Foudn beneath the locus cereleus (which is slightly above)
36
What is the clinical presentation for someone who has a lesion in their hypoglossal nerve/nucleus?
What cranial nerve number is this?
* Test: Stick tongue out
* Tongue will deviate to side with lesion
* Found close to midline
* Cranial Nerve 12
37
What is the route of the hypoglossal nerve from inside the brainstem to outside?
* Axons move **anteriorly** at the **upper medulla level**
* Leave **just** **lateral** to **corticospinal pyramids**
38
Where is the **dorsal nucleus of the vagus (X) nerve** found?
What fibres does it send out?
Where do they go?
* **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**
*
39
What does the nucleus ambiguus supply?
Motor or sensory?
* **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**
40
What do the muscles of the pharynx, larynx and soft palate have in common?
* They are all Brachial Muscles which are derived from the 4th & 6th pharyngeal arch musculature
*
41
What fibres are found in the Vagus (X) Nerve?
42
The **nucleus** **ambiguus** allows for safe....
* **Speech**
If you have a damaged nucleus --\> foreign bodies can go down airway --\> causing pneumonia (can kill)
43
What do cells in the **nucleus** **ambiguus** and **around it** form and supply?
* Forms **Ventral Respiratory Centre**
* Supplies **heart**
**NB:** Some axons from it join the vagus nerve & cranial accessory nerves
44
What is the mneumonic for remebering eye muscles innervation?
LR6 SO4 3
45
Where abouts are the following located?
- Level?
- Position?
* Dorsal Nucleus of Vagus Nerve (X)
* Nucleus Ambiguus
46
What does the abducens nerve (6th cranial nerve) supply?
* Lateral Rectus
47
Where is the abducens nucleus?
* **Pons**
* Near **Floor** of **4th Ventricle**
*
48
What happens in left abducens palsy?
* Patient cannot look to the left hand-side (right eye works but left does not)
49
What commonly affects the abducens nerve?
(What cranial nerve number is it?)
* Any **problems affecting** the **skull**
* It is a **thread-like nerve**
* **Cranial Nerve 6**
50
What is **Bell's palsy**?
* **Loss** of **muscle** **control** on **one** **side** of the **face**
51
What do **axons** of the **facial** **motor** **nucleus** do that is **unusual**?
* They **loop** around the **abducens** **nucleus**
* They then **exit** the **brain** **stem** through the **front** **side**
This is due to embryology
52
What **pharyngeal** **arch** musculature does the **facial motor nucleus** supply?
* 2nd pharyngeal arch (important in facial expression)
53
What does the **facial** **nerve** supply? (2 things)
(what cranial number is it?)
* Muscles of Facial Expression
* Stapedius (ear)
54
What is facial palsy?
Same as Bell's Palsy
Loss of muscle control on one side of the face
55
What can cause Bell's palsy?
* Can be due to **herpes** **virus** (unkown for certain)
56
How can we test the facial motor nucleus?
* 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
57
Which part of the **trigeminal** **nucleus** is found at the **rostral part of the pons**?
* Chief Sensory Nucleus (V) (usually just does discriminative touch of the face)
58
What does the **motor nucleus** of the **trigeminal** **nerve** supply?
* **Muscles of Mastication**
* **Tensor Muscles** (Ear)
These are the 1st pharyngeal arch musles
59
How do you **test** the **motor** **nucleus** of the **trigeminal** **nerve**?
* Ask patient to **clench their teeth**
* Feel the **masseter / temporalis** **contracting** on **either side**
* **Symmetry** is important!
60
Which **pharyngeal** **arch** **musculature** does the **motor** **nucleus** of the **trigeminal** **nerve** supply?
* 1st pharyngeal arch
61
Label this image of the midbrain.
62
What are the **2 parts** of the **oculomotor** **nucleus**?
1. **Somatic Motor Nucleus Part**
2. **Edinger-Westphal Nucleus** (parasympathetic part)
63
What are the **2 functions** of the **oculomotor** **nerve**?
(Which cranial nerve?)
* **Somatic Motor Part** --\> supplies **somatic** **muscles** of the **eye**
* **Parasympathetic Part (edinger-westphal)** --\> **controls** **dilation** of the **pupils** (constrictor papillae)
64
Is the **optic** **nerve** involved in the **light** **reflex**?
* Yes
* It is needed for the **detection of light (afferent pathway)**
65
How can we simultaneously test the **optic** **nerve** & **oculomotor** **nerve**?
* 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**
66
What is the light reflex pathway (generally)?
* **Optic** **Nerve** --\> DETECTS LIGHT
* **Edinger-Westphal Nucleus** --\> causes Oculomotor to --\> PUPILLARY CONSTRICT
*
67
What **2/3 ways** can the **light** **reflex** present a **problem**?
* One Side not responding at all
* Both sides not responding at all
* One side responding more than the other side (should be equal)
68
Where is the oculomotor nucleus found?
69
What is the **afferent** & **efferent** **limb** of the **light** **reflex**?
* Afferent Limb --\> Optic Nerve (2)
* Efferent Limb --\> Oculomotor Nerve (3)
70
Does the light reflex require **visual** **cortex**?
* No
71
Describe the light reflex pathway.
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
What is the role of the pretectal nucleus?
* 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
What does the **posterior** **cerebral** **artery** supply in the **midbrain**?
* Corticospinal Tract
* Substantia Nigra
* Oculomotor Fibre
74
What is the **route** of the **PCA** **around** the **midbrain**?
* It **winds** **around** the **midbrain** --\> **towards** the **back** of the **forebrain**
75
How is the oculomotor fibre lost via a PCA lesion?
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
What are the effects of a PCA lesion?
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
What is the **main** **overall** **function** of the **cerebellum**?
1. Coordinate Movements
2. Balance
78
What does the **lateral** **hemisphere** of the **cerebellum** coordinate?
* **Coordinates** **voluntary** **movements** (especially **upper** limb)
NB: It does many other things too
79
What is the **anterior** **lobe** of the **cerebellum** important for?
* Important in **walking**
80
What is the **midline** **part** of the **cerebellum** important for?
* Important in **balance**
**NB**: Specifically the **floculomotor** **lobe**
81
What is **ataxia**?
**Uncoordinated movement**
82
What is the **midline** called?
* Vermis ('worm like')
83
Why is the **tonsil** **clinically** relevant?
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
What **2 things** will cause the **tonsils** of the **cerebellum** to try to **escape** down the **foramen** **magnum**?
1. High Intracranial Pressure (ICP)
2. Lumbar Puncture
85
Which part of the **brainstem** is **breathing** organised in?
* Medulla
86
Summarise how the **cerebellum** allows for **accurate** **movement**.
* **Cerebellum** --\> coordinates movement
* It **influences** **motor** **areas** of the **cerebral** **cortex** which **primarily** **control** **movements**
* It does **_not_** **control** **motor** **neurones** **itself**
87
What is **intention** **tremor**?
* Occurs when **cerebellum** is **_not_** **correcting** the **motor** **function** from **M1**
88
How does the body **compensate** for a **problem** in the **cerebellum** when **doing** **movements**?
* 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
**Via** what does the **cerebellum** **influence** **motor** **movements**?
* Thalamus
* Cerebral Cortex
90
What is **ataxia** a sign of?
* That the **cerebellum** is **_not_** **working** **properly**
* It is **_not_** **coordinating** **movements** like it should be
91
If you can do **accurate** **movement**, what does this mean?
* Relevant side of the **cerebellum** is in **good function (ipsilateral)**
92
Where is the **vermis**, **hemisphere** and **tonsil**?
93
What does the **cerebellum** look like from **above**?
94
What are the different parts of the **cerebellum (cortex)**?
* **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
What is the **cerebellar** **cortex**?
* **Grey** **matter** that is **folded** into **folia**
96
Where is the Nodule?
Why is it important?
* Important in **Balancing**
* Can only be seen with a **sagital** **section** (from side)
* It is **very close** to the **4th ventricle**
97
What are the **3 layers** of the **cerebellar** **cortex**?
* **Molecular Layer** (outside)
* **Purkinje Cells**
* **Granule Cell Layer** (inside)
98
What are the **only** **axons** that leave the **cerebellar** **cortex**?
* **Purkinje Cell Axons**
99
Where do the **_axons_** and **_dendrites_** of the **purkinje** **cells** in the **purkinje** **cell** **layer** pass through?
* **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
What is found in the **_molecular_** **layer** of the **cerebellar** **cortex**?
* **Dendrites** of **Purkinje** **Cells** found
101
What is found in the **Purkinje** **cell** **layer** of the **cerebellar** **cortex**?
* Axons of Purkinje Cells
* These go to the **subcortical** **white** **matter**
* **Single** **row** of **purkinje** **cells**
102
What is found in the **granule** **cell** **layer** of the **cerebellar** **cortex**?
* 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
What is the **only** **_output_** from the **cerebellar** **cortex**?
* **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
Where are the deep nuclei in the cerebellum?
What do they do?
* 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
Where is the fastigial nucleus?
Where does it project to? (2 places)
* Near the **midline**
Projects to (2) places:
1. **Vestibular Nuclei**
2. **Reticular Formation**
106
Where is the dentate nucleus?
Where does it project to?
* **Toothy** **Shape** (hence the name)
* One in either hemisphere (just like fastigial nucleus)
Projects to the **Thalamus**
* **Influences** the **Motor** **Cortex** via **Thalamus**
107
Where is the **fastigial** & **dentate** nucleus located and where do they project to?
108
Where does the **processing** occur in the **cerebellum**?
* Cerebellar Cortex
109
What cell types are the output axons from the cerebellar cortex and are they inhibitory or excitatory?
* Purkinje Cell Axons
* Inhibitory (-)
110
What are the 2 types of afferent axons entering the cerebellum?
1. Mossy Fibres
2. Climbing Fibres
111
Is the input into the cerebellar cortex excitatory or inhibitory?
* Excitatory
112
Where does the output of the Purkinje Cell synapse?
* **Deep Nuclei**
* Onto **Efferent** **Axon** leaving **Cerebellum**
113
Where do incoming fibres into cerebellar cortex send collaterals to?
Are these excitatory or inhibitory?
* 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
What forms the **climbing** **fibres**?
Where do they **originate** from?
* **Olivocerebellar** **Fibres**
* Originate only from **inferior** **olivary** **nuclei**
115
Where is the principal inferior olivary nucleus found? (level?)
* Open Medulla
* Ventral Side
*
116
Where abouts is the bump formed by the inferior olive?
* This is why it is called an **olive**
* Found **lateral** to **pyramids**
117
What does the **inferior** **olivary** **nucleus** give rise to?
* **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
What are the **_main_** sources of **mossy** **fibres**?
* **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
Where is the information originally from? (show the route)
* Route: Cerebral Cortex --\> Pons --\> Cerebellum
* Originally information comes from the Cerebral Cortex (widespread areas)
120
From which part of the brainstem does the mossy fibres come from? (level)
* **Pons**
* They pass to the **cerebellum** via the **Middle** **Cerebellar** **Peduncle**
121
How are the pontine nuclei distributed?
* They are **intermingled** **among** the **corticospinal** **tract** **bundles**
122
Generally describe how the cerebral cortex & cerebellum work together using mossy fibres.
* 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
Describe the path of the neurones from the pontine nuclei (mossy fibres).
* 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
How many **climbing** **fibres** does each **purkinje** **cell** have?
* There is **(1) Climbing Fibre** per **Purkinje Fibre**
125
What is the **function** of the **climbing** **fibre**?
* When it **fires** it **_helps_** the **purkinje cells**
* They give **error** **signals** to the **cerebellar** **cortex**
126
What do **excitatory** **inputs** **synapse** with in the **cerebellar** **cortex**?
* Lots of **dendrites** of the **granule** **cells**
127
What do the mossy fibres synapse with?
Where do they come from?
* Mainly **pontine** **nuclei** (which get fibres from cerebral cortex)
* Synapse with **granule cells**
128
Gives **(3) examples** of **destinations** from the **outputs** of the **cerebellum**.
1. Thalamus
2. Red Nucleus
3. Vestibular Nuclei
129
Where does the axons of granule cells go?
What do they synapse with?
* **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
Overall, describe the information pathway in the cerebellar cortex.
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
What do mossy fibres do as soon as they come into the cerebellum? (2 things)
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
What is the source of mossy fibres & climbing fibres in the cerebellum?
* Mossy Fibres --\> **Pontine** **Nuclei**
* Climbing Fibres --\> **Inferior Olivary Nuclei**
133
What are the signs of **cerebellar** **hemisphere** **(lateral part) lesions**? (3 things)
1. Intention Tremor
2. Dysdiadochokinesia
3. Speech Problems
134
What is **dysdiadochokinesia**?
* **Cannot** do **rapid alternating movements**
135
Are the effects of a **cerebellar** **hemisphere** **lesion** **_contralateral_** or **_ipsilateral_**?
* **Ipsilateral**
* Symptoms are found on the **same** **side** as the **lesion**
136
What is **intention** **tremor**?
How do you **compensate**?
* 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
What is the **cerebellum** important for doing?
* **essential** for executing **smooth non-stereotypic movements**
138
How does the climbing fibre carry out its function?
* 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
What do lesions in the anterior lobe (orange) cause in terms of symptoms? (1 thing)
Who is this common in?
* **Gait** **Ataxia** (walking problem)
* **Common** in **Alcoholics**
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Why is the **effects** of the **cerebellar** **lesion** **ipsilateral**?
* 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
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Which **deep** **nuclei** do **purkinje** **fibres** in the **cerebellar** **hemisphere** send their axons to?
* **Dentate**
NB: Each part of the cortex sends axons to corresponding nuclei (dentate is furtherest out so this makes sense)
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Through what does the **lateral** **cerebellum** **influence** **movements**?
* Thalamus
* Motor Cortex (M1)
Corticospinal Tract
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Which tracts is the **fastigial** **nucleus** involved in? (name 3)
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**
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**Via** what does the **vestibulocerebellum** influence the **3 tracts**?
* Fastigial Nucleus
Influencing motor control via 3 tracts
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What are the **effects** of a **floccular-nodular lobe lesion**?
1. Truncal Ataxia
2. Nystagmus
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How does the **floccular-nodular lobe** influence **motor** **control**, via what? (name 3)
1. Vestibulospinal Tract
2. Reticulospinal Tract
3. Medial Longitudinal Fasciculus
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What **commonly** affects the **floccular-nodular lesion**?
* Medulla Blastoma
* Common Tumours in Children
They won't be able to sit upright due to this part of the cerebellum
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What is the obvious sign of someone who has a **lesion** of **floccular**-**nodular** **lobe**?
* Loss of Balance
* Unable to sit/stand upright
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What is the **floccular**-**nodular** **lobe**?
* **Vestibular** **Part** of the **Cerebellum**
* **Balance**
* It enables you to **stay** **upright**
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Where is the **floccular**-**nodular** **lobe** **found**? (roughly)
* Behind Cerebellar Peduncle
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Which **deep** **nuclei** & **lobe** of the cerebellum is influences **motor function in 3 tracts?**
* Fastigial Nuclei
* Floccular-Nodular Lobe
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What is the floccular-nodular lobe important in?
* Balance
* Sitting/standing upright
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From where does the **fastigial** **nucleus** **_receive_** **information** and where does it **send** **it** **to**?
* Receive from: **Floccular-Nodular Lobe**
* Send axons to: **Vestibular** **Nuclei** & **Reticular** **Formation** & **Medial Longitudinal Fasiculus**
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What **reflex** is the **medial** **longitudinal** **fasiculus** involved in?
* Vestibulo-Ocular Reflex
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Where is the **medial** **longitudinal** **fasiculus** found?
* Near Midline
* Along the Brainstem
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Which **4** **nuclei** is the **medial** **longitudinal** **fasiculus** connected to?
* Oculomotor (3)
* Trochlear (4)
* Abducens (6)
* Vestibulocochlear (8)
*
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What is the **main** **function** of the **medial** **longitudinal** **fasciculus**?
* To **connect** **nuclei** of **nerves controlling eye movement** (LR6SO43) with the **vestibular nuclei** (working with **floccular**-**nodular** **lobe**)
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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?
* **Lateral** **Part** of the **Floor** of the **4th Ventricle**
* Linked to **Utricle** & **Saccule**
* **Vestibular Ganglia**
* **Floccular-Nodular Lobe**
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What do the vestibulospinal tracts do? (generally)
Are they involuntary or voluntary?
* Keep you upright
* They are **_not_** **involved** in **voluntary** **movement**
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What is the **symptom** of a **lesion** **_above_** the **vestibulospinal** **tract**?
Why does this occur?
* **Decerebrate Rigidity**
* **Vestibulospinal** **tract** is normally subject to **descending** **inhibitory** **influences** --\> thus causing **rigidity** if this **inhibition is lost**
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What is the location in terms of **spinal** **cord white matter** for the **vestibulospinal tract?**
* **Ventral** **Part** of the **Spinal Cord White Matter**
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From which **2 places** does the **lateral** **vestibular** **nucleus** receive information?
1. Floccular-Nodular Lobe
2. Vestibular Apparatus
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What is **decerebrate** **rigidity**?
* When all the **extensor** **muscles** **contract a lot**
* Due to **loss** of **inhibition** causing **muscle** **overdrive** so they **all contract**
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Where does the **lesion** have to occur for **decerebrate** **rigidity** to occur?
* **Above** the **Lateral Vestibular Nucleus**
* To the **descending inhibitory influences** which usually come from the **forebrain**
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Can you **survive** with **no** **cerebellum**?
* Yes
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What does the **reticular** **formation** give rise to?
* Reticulospinal Tracts (medial & lateral tracts)
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What is the **reticulospinal** **tract** important in?
* Motor Pathways
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Where does the **brainstem** **reticular** **formation** **receive information** from?
What **kind** of **information** is this?
* **Cerebral Cortex**
* **Sensory** **Information** --\> particularly **nociception**
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Which **ascending** **tract** may give **collaterals** to the **reticular** **formation**?
What is the reticular information important for?
* Spinothalamic Tract
* **Reticular** **activating** **system** to **keep you alert**
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What **important** **centres** can some **reticular** **formation** nuclei form?
* Some nuclei form 'respiratory centres'
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What monoamine does the raphe nuclei project all over the CNS?
5-HT
Raphe Nuclei found in the midline mainly (lowest is medulla)
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What is the **reticular** **formation** involved in?
Things you do not want to think about
* Control of **Breathing**
* Control of **Heart** **Rate**
* **Involuntary Movements**
* **Alert** **System** (keep you awake)
*
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How can the **reticular** **formation** be **helpful** with a **corticospinal** **tract** **lesion**?
* 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**
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Where is the reticular formation found?
* Fills all the spaces between the other structures we talk about
NB: Nuclei are indicated
