Anat 401 > Brainstem nuclei > Flashcards

Brainstem nuclei Flashcards

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1
Q

What are the major ascending tracts of the brainstem?

A

Dorsal columns medial lemniscal pathway, spinothalamic tract and the trigeminothalamic tract

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2
Q

What are the afferent tracts that go into the inferior cerebellar peduncle?

A

Spinocerebellar tract, cuneocerebellar tract, olivocerebellar tract and the vestibulocerebellar tract

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3
Q

What are the major descending tracts of the brainstem?

A

Corticospinal tract, corticobulbar tract, corticopontine tract, vestibulospinal tract, rubrospinal tract, reticulospinal tract

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4
Q

What does the rubrospinal tract do?

A

It facilitates unconscious flexion of the upper limbs

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5
Q

What do the vestibulospinal and reticulospinal tracts do?

A

Control postural (anti-gravity) muscles

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6
Q

Where do the vestibulospinal and reticulospinal tracts project to?

A

They project to the spinal motor neurons

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7
Q

Where does the corticopontine tract synapse?

A

Onto neurons in pontine nuclei

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8
Q

Where does the corticobulbar tract synapse?

A

Onto cranial nerve nuclei

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9
Q

Where does the corticospinal tract descend to?

A

The ventral horn of the spinal cord

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10
Q

What are the pyramidal tracts?

A

The corticospinal, corticobulbar and corticopontine tracts

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11
Q

What are pyramidal tracts?

A

Tracts that control the direct and conscious control of movements

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12
Q

What are extrapyramidal tracts?

A

Tracts that control the indirect and unconscious movements

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13
Q

What are the extrapyramidal tracts?

A

The vestibulospinal, reticulospinal and rubrospinal tracts

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14
Q

What is the pathway for the corticospinal, corticopontine and corticobulbar tracts?

A

Neurons start in the cerebral cortex, the move into the internal capsule and they form cerebral peduncles in the ventral midbrain before splitting to perform individual functions

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15
Q

What are the brainstem nuclei in the midbrain?

A

Oculomotor nucleus, trochlear nucleus, Edinger-Westphal nucleus, mesencephalic nucleus and the red nucleus

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16
Q

What is the red nucleus also known as?

A

Mickeys eyes

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17
Q

What is the red nucleus? What does it control?

A

It is rubrospinal fibers that cross the midline and it does motor control, especially flexion of the upper limbs

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18
Q

What tracts are found in the cerebral crus?

A

The corticospinal, corticopontine and corticobulbar tracts

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19
Q

Where is the cerebral crus located?

A

At the level of the midbrain

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20
Q

What is the cerebral crus?

A

It is the anterior part of the cerebral peduncle that contains important motor tracts that connect the cerebral cortex to the brainstem and spinal cord

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21
Q

What disease does the substantia nigra play a big role in?

A

Parkinson’s disease

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22
Q

What type of neurons are found in the substantia nigra?

A

Dopaminergic neurons

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23
Q

Where do the dopaminergic neurons of the substantia nigra project to?

A

The striatum

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24
Q

What is the ventral tegmental area?

A

A group of dopaminergic neurons in the midbrain

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25
What nuclei are found in the pons?
Pontine nuclei, locus coeruleus, raphe nuclei and corticobulbar nuclei
26
What corticobulbar nuclei are found in the pons?
Abducens nucleus, Superior and inferior salivary nuclei, chief/main trigeminal nucleus, trigeminal motor nucleus and the facial motor nucleus
27
What nuclei are at the level of the medulla?
Gracile and cuneate nuclei, hypoglossal nucleus, dorsal motor vagal nucleus, nucleus ambiguous, solitary tract nucleus, vestibular nuclei, spinal trigeminal nucleus, inferior olivary nucleus, raphe nuclei
28
Is the reticular formation organized?
Yes, on a microscopic level
29
What is the reticular formation?
Loosely arranged neuron cell bodies intermingled with bundles of axons
30
Where does the reticular formation extend to?
Extends upwards to the level of the thalamus and downwards to be continuous with the interneurons of the spinal cord
31
What does the reticular formation do?
It receives and integrates input from all regions of the CNS and processes a great deal of information
32
What are the different functions of the reticular formation?
It controls arousal and consciousness The reticulospinal tracts help maintain tone and posture It is involved in autonomic relays (respiratory, cardiac and visceral) Is involved in the perception of pain
33
What does the control of arousal and consciousness of the reticular formation involve?
Reticular activating system (RAS) Biological clock Involved in sleep (especially REM)
34
What afferent projections does the reticular formation receive?
Projections from: Collateral branches of all sensory pathways (general or special sensation) Cerebral cortex Cerebellum Basal ganglia (corpus striatum) Vestibular nuclei, visual pathway Thalamus and hypothalamic nuclei
35
What efferent projections does the reticular formation send?
Projections from: Reticulobulbar and reticulospinal tracts Descending pathway to sympathetic and parasympathetic outflow of ANS Cerebellum Basal ganglia (corpus striatum) Thalamus and hypothalamic nuclei
36
What are the 3 main zones of the reticular formation?
The raphe nuclei, medial zone and lateral zone
37
What are the nuclei of the reticular formation?
Raphe nuclei Central group of nuclei Cholinergic (Ach) Catecholinergic Nuclei for cardiorespiratory centre Nuclei for visceral sensations
38
What tract are the central group of nuclei a part of?
The reticulospinal tract
39
What type of nuclei are Raphe nuclei?
Serotonergic
40
What are Cholinergic nuclei involved in?
Motor functions (locomotion), consciousness and arousal (reticular activating system)
41
Cathecholinergic nuclei include what neurons found where?
Dopaminergic neurons - substantia nigra Noradrenergic neurons - Locus coeruleus
42
Can a normal brain function without the reticular activating system (RAS)?
No
43
What does damage to the reticular activating system due?
Causes unconsciousness
44
What is the reticular activating system?
Ascending fibers of the reticular formation
45
What does the reticular activating system do?
Receives input from several sources and projects the inputs to the thalamus and then the cortex to promote arousal and consciousness
46
What does a lesion or tumour to the lateral zone of the reticular formation cause?
It could lead to unconsciousness or death
47
What does the lateral zone of the reticular formation do?
It controls the cardiorespiratory 'reflex'
48
What is the pathway for the lateral zone of the reticular formation?
It receives inputs from the glossopharyngeal nerves (chemo/baroreceptors) to solitary tract nucleus (NTS). The NTS then projects to the reticular zone respiratory centres which modulates the vagus efferent pathway to control breathing and heart rate
49
How are the neurons of the lateral zone of the reticular formation?
Reticular formation neurons involved in respiratory and cardiovascular control are intermingled within the medulla
50
Which zones do reticulospinal tracts come from?
Medial and lateral zones
51
What do the reticulospinal tracts of the medial zone do?
They control muscle tone and posture and balance via axial (core) musculature They are excitatory to leg extensors and arm flexors (ex: carries info telling hamstrings to contract before you bend forward - prevents you from falling)
52
What do the reticulospinal tracts of the lateral zone do?
They inhibit limb musculature during sleep Actively suppresses muscle activity during REM sleep
53
Where do reticulospinal neurons receive projections from?
Many areas including the basal ganglia, vestibular nuclei, and substantia nigra, somatosensory and motor cortex
54
What are the reticulospinal tracts?
A major alternative route (to the CST/pyramidal tract) by which spinal motor neurons are controlled, both influencing motor neurons directly and regulating the sensitivity of spinal reflex arcs
55
Are reticulospinal tracts pyramidal or extrapyramidal?
Extrapyramidal
56
Where do the reticulospinal tracts synapse?
Directly onto the spinal cord
57
What motor neurons of the spinal cord do the reticulospinal tracts terminate on?
Alpha and gamma motor neurons
58
What do the reticulospinal tracts act directly onto?
Lower motor neurons
59
What is a horizontal gaze?
Following an object that is moving horizontally
60
What causes internuclear ophthalmoplegia?
A lesion to the medial longitudinal fasciculus
61
What is internuclear ophthalmoplegia?
A condition that causes impaired movement when looking to the side. The affected eye cannot move towards the nose when looking contralaterally and the unaffected eye experiences nystagmus
62
What is nystagmus?
Involuntary rapid and repetitive eye movement
63
Is internuclear ophthalmoplegia contralateral, ipsilateral or bylateral?
Ipsilateral. An injury to the right medial longitudinal fasciculus causes a right internuclear ophthalmoplegia
64
What is the vestibulo-ocular reflex (VOR)?
An involuntary reflex that stabilizes visual images on the retinas during head movement by producing eye movements in the direction opposite to that of the head
65
Is the vestibulo-ocular reflex fast?
Yes, it is one of the fastest reflexes in the body, acting as the body's "internal steadicam" or optical image stabilizing system
Anat 401
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