Brainstem & Cerebellum Flashcards

1
Q

What are the 3 general functions of the brainstem?

A
  1. Conduit
  2. Integrative
  3. Cranial nerve
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2
Q

How does the brainstem act as a conduit?

A

It allows ascending and descending pathways to reach the thalamus and cerebellum from the spinal cord

It contains relay nuclei

These are a collection of grey matter (nerve cell bodies) within the CNS

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3
Q

How does the brainstem have an integrative function?

A

It is involved in the control of cardiovascular, respiratory and consciousness

Consciousness is controlled by the reticular formation

It is involved in complex motor patterns (e.g. balance)

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4
Q

What does locked in syndrome result from?

A

An infraction of vessels in the ventral pons

as the reticular formation is intact, the patient is conscious but is unable to move

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5
Q

What is the ‘cranial nerve” function of the brainstem?

A

These are the head’s equivalent to spinal nerves

They are involved in sight, hearing, equilibrium and gustation

There are cranial nerve nuclei and reflex centres within the brainstem

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6
Q

What are the 3 structures within the brainstem?

A
  1. Midbrain
  2. Pons
  3. Medulla oblongata
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7
Q

What are the rostral, caudal, ventral and dorsal relationships of the brainstem?

A

Rostrally:

  • midbrain is continuous with the diencephalon

Caudally:

  • medulla is continuous with the spinal cord at the level of the foramen magnum

Ventrally:

  • clivus of occipital bone

Dorsally:

  • cerebellum
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8
Q

What components of the ventricular system run through the brainstem?

A
  1. IVth ventricle (IVth)
  2. Cerebral aqueduct (Caq)

This is continuous with the central canal of the spinal cord

These are cavities containing cerebral spinal fluid

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9
Q

Label the components of the ventricular system and brainstem

A
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10
Q

Which cranial nerves arise from the brainstem?

A

10 out of 12 cranial nerves arise from the brainstem

These are part of the PNS

They have sensory and motor parts

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11
Q

At any level of the brainstem, which 3 areas can be identified in cross section?

A

Tectum:

  • the tectum is only present in the midbrain

Tegmentum:

  • this contains cranial nerve nuclei and the reticular formation

Basal:

  • descending motor fibres travel through here
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12
Q

Label the different areas in cross section of the brainstem

A
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13
Q

Where is the tectum found?

A

It is posterior to the ventricular system

The only region with substantial tectum (roof) is the midbrain (superior and inferior colliculi)

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14
Q

Where is the tegmentum found?

What does it contain?

A

Found anterior to the ventricular system

it contains cranial nerve nuclei and tracts, reticular formation and some ascending/descending pathways

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15
Q

Where is the basal found?

What does it contain?

A

It is found most anteriorly

it contains descending fibres from the cerebral cortex (pyramids, cerebral peduncles)

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16
Q

Which junction is labelled?

A

Pontomedullary junction (PMJ)

this is between the medulla of the brainstem and the pons

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17
Q
A
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18
Q

Where is the rhomboid fossa?

What is this?

A

It forms the floor of the IVth ventricle

It is exposed when the cerebellum is removed

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19
Q

Label the ventral view of the medulla

A
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20
Q

What is the passage of the cranial nerves visible on the ventral view of the medulla like?

A

IX and X are lateral to the olives in the anterolateral sulcus

XI is below X

IX, X and XI all leave through the jugular foramen

XII emerges between the pyramids and olives and leaves through the foramen magnum

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21
Q

What is behind the pyramids?

A

Descending motor fibres - the pyramidal tract

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22
Q

What happens at the decussation of pyramids?

A

Fibres travelling from the cerebrum cross over and travel on the opposite side of the spinal cord

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23
Q

Label the dorsal view of the medulla

A
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24
Q

What is the obex?

A

The point at which the IVth ventricle becomes continuous with the central canal of the spinal cord

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25
Q

What is the difference between the fasciculus cuneatus and fasciculus gracilis?

A

Fascicles contain a tract of white matter (axons)

Fasciculus cuneatus:

  • contains ascending sensory information from the upper limb

Fasciculus gracilis:

  • contains sensory information from the lower limbs
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26
Q

What is the difference between the open and closed medulla?

A

If you cut below the obex, this section is the closed medulla as there is brain tissue dorsally and centrally

If you cut above the obex, this is the open medulla as the IVth ventricle is anterior

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27
Q

What are the sections through the midbrain?

A
28
Q

Label the closed and open medulla sections

A

White matter is shown as black due to the staining

the nucleus within the olive (shown in rostral medulla) is part of the visual system

29
Q

What are the functions of the anterior median fissure, anterolateral sulcus and posterolateral sulcus?

A

Anterior median fissure:

  • separates the two pyramids of the medulla
  • contains descending motor fibres

Anterolateral sulcus:

  • separates pyramids from olives
  • hypoglossal nerves emerge here

Posterolateral sulcus:

  • dorsal to the olives
  • vagus and glossopharyngeal nerves emerge here
30
Q

Which pathway are the gracile and cuneate fascilicles part of?

A

They are part of the dorsal column pathway

this carries sensory information from the body to the brain

31
Q

What 2 junctions are labelled?

A
32
Q
A
33
Q

Label the ventral view of the pons

A
34
Q

What travels in the basilar groove?

A

Basilar artery

35
Q

Which nerves arise from within the cerebellopontine angle?

A

VII (facial) and VIII (vestibulocochlear)

36
Q

Label the dorsal view of the pons

A
37
Q

What is the function of the cerebellar peduncles?

A

They connect the brainstem to the cerebellum

38
Q

What forms the facial colliculus?

A

Fibres of the facial nerve (VII) loop around the nucleus of CN VI

they emerge at the pontomedullary junction

the facial colliculus is due to the fibres of CN VII looping around VI

Injury to CN VI can negatively affect VII

39
Q

Label the cross sections of the caudal and rostral pons

A
40
Q

How is the pons positioned?

A

It is transversely orientated and bridges between the two cerebellar hemispheres

Caudally:

  • medulla (pontomedullary junction)

Rostrally:

  • midbrain (pontomesencephalic junction)
41
Q

Where do the nerves on the ventral view of the pons emerge from?

A

Cerebellopontine angle:

  • this is where the medulla and pons join the cerebellum laterally
  • facial and vestibulocochlear emerge here

Pontomedullary junction:

  • abducens nerve emerges here

mid-pontine level:

  • trigeminal nerve enters here
42
Q

What are the functions of the 3 cerebellar peduncles?

A

Superior:

  • connects the midbrain to the cerebellum
  • forms roof of IVth ventricle

Middle:

  • connects pons to cerebellum

Inferior:

  • connects medulla to cerebellum
43
Q

What junction is shown?

A

Pontomesencephalic junction of the midbrain

44
Q

Label the ventral view of the midbrain

A
45
Q

Where do CN III and IV emerge from?

A

CN III emerges from the interpeduncular fossa between the cerebral peduncles

CN IV emerges from the dorsal view of the midbrain

46
Q

Label the ventral view of the midbrain

A
47
Q

What is the role of the brachium of the superior and inferior colliculi?

A

The brachium connects the colliculi to the thalamus

48
Q

What is significant about CN IV?

A

It is the only cranial nerve that emerges from the dorsal view of the midbrain

49
Q

Label the midbrain at the level of the inferior colliculi?

A
50
Q

What is the main feature of anterior view of the midbrain?

A

The main feature is the cerebral peduncle

This is separated by the interpeduncular fossa

The oculomotor nerve emerges from the interpeduncular fossa

51
Q

What are the main features of the dorsal view of the midbrain?

A

The paired superior and inferior colliculi

52
Q

What is the difference in function of the superior and inferior colliculi?

A

Superior colliculus:

  • associated with the visual pathway

Inferior colliculus:

  • Associated with the auditory pathway
53
Q

Where does the trochlear nerve emerge from?

A

Inferior to the inferior colliculi and at junction with the pons

it is the only nerve to emerge from the dorsal surface

54
Q

What is the reticular formation?

A

A complex, multisynaptic network of neurones within the tegmentum of the brainstem

55
Q

What are the roles of the reticular formation?

A

Reticular nuclei:

  • give rise to a descending motor pathway - reticulospinal tract

Vital autonomic centres:

  • e.g. respiratory, cardiovascular

Cells giving rise to ascending reticular activating system:

  • these cells pass to the cortex and are involved in consciousness
  • damage leads to coma
  • pain modulation
  • sleep wake cycle
  • arousal
56
Q

Label the blood supply to the brainstem

A
57
Q
A
58
Q

Label the blood supply to the brainstem

A
59
Q

Label the cranial nerves

Which ones are missing and where do they originate from?

A

I and II are extensions of the forebrain

IV comes from the dorsal aspect of the midbrain

60
Q

What actions is the cerebellum primarily involved in?

A

It is primarily involved in coordination of movement, maintenance of balance and posture

61
Q

What is the location of the cerebellum?

A

It is found under the occipital lobes of the cerebral hemispheres

it is attached to the brainstem by three paired cerebellar peduncles - superior, middle and inferior

62
Q

Label the cerebellar peduncles

A
63
Q

What are the views of the cerebellum?

A
64
Q

Label the superior/dorsal surface of the cerebellum

A

The vermis is the middle portion between the 2 hemispheres

65
Q

Label the inferior/ventral surfaces of the cerebellum

A