Overview of Brainstem Organisation Flashcards

1
Q

What is the brainstem a gateway between?

A

Spinal cord and higher cortical areas

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2
Q

Why do anencephalic babies survive?

A
Born without forebrain
Have brainstem
- Breathe
- Suckle
- Swallow
- Cry
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3
Q

What are the functions of the brainstem?

A

Reflexive and unconscious behaviour

Modulation of arousal and conscious states

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4
Q

What are the parts of the brainstem?

A

Midbrain
Pons
Medulla oblongata

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5
Q

Which part of the brainstem is most rostral and continuous with the structures above it?

A

Midbrain

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6
Q

Which part of the brainstem is most caudal and continuous with the spinal cord?

A

Medulla

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7
Q

In which cranial fossa is the brainstem?

A

Posterior

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8
Q

What is the rostral to caudal boundary of the brainstem?

A

Mammillary bodies rostrally to pyramidal decussation caudally

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9
Q

Describe the dorsal aspect of the midbrain

A

Two pairs of bumps = superior and inferior colliculi

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10
Q

What are the superior colliculi important for?

A

Eye movement control

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11
Q

What are the inferior colliculi important for?

A

Hearing

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12
Q

Describe the dorsal aspect of the pons

A

Linked with cerebellum via cerebellar peduncles

Limited by 4th ventricle

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13
Q

What are the cerebellar peduncles?

A

White matter tracts

Where cerebellum joins rest of brain

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14
Q

Describe the dorsal aspect of the medulla

A

Caudally, dorsal columns and nuclei:

- Gracile and cuneate fasciculus

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15
Q

What happens at the gracile and cuneate fasciculi?

A

Synapse of spinothalamic tract, carrying somatosensory info

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16
Q

Describe the ventral aspect of the midbrain

A

Cerebral peduncles between interpeduncular fossa

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17
Q

What are the cerebral peduncles?

A

White matter tracts coming down from cerebrum and out carrying corticospinal tracts = motor information

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18
Q

Describe the ventral aspect of the pons

A

Attached to cerebellum dorsolaterally by cerebellar peduncles

  • Superior
  • Middle
  • Inferior
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19
Q

Describe the ventral aspect of the medulla

A

Rostrally, two bulges = inferior olivary nuclei

Pyramids descending to pyramidal decussation

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20
Q

What are the inferior olivary nuclei important for?

A

Hearing

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21
Q

What is the tectum?

A

Roof
Another name for 4 superior and inferior colliculi
Only applies to midbrain

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22
Q

What is the tegmentum?

A

Most of action of brainstem

Continuous with spinal cord

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23
Q

Where are the cranial nerve nuclei?

A

Dorsal tegmentum

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24
Q

What is in the basus of the brainstem?

A

Nuclei and long fibre tracts containing motor control to body

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25
Q

Where is the motor control of the body in the brainstem: dorsally or ventrally?

A

Ventrally

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26
Q

Where is the reticular formation?

A

Tegmentum

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27
Q

What do cranial nerves supply?

A

Somatic and visceral motor and sensory information to head

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28
Q

Where else do CN IX and X supply visceral sensory and motor innervation to?

A

Neck
Chest
Most abdominal organs

29
Q

From which surface do most cranial nerves exit the brainstem?

A

Ventral

30
Q

Which cranial nerve doesn’t exit the brainstem ventrally?

A

CN IV

31
Q

Which cranial nerves are exclusively motor?

A
III
IV
VI
XI
XII
32
Q

Which cranial nerves are exclusively sensory?

A

I
II
VIII

33
Q

Which cranial nerves are mixed?

A

V
VII
IX
X

34
Q

What is the rule of 4s?

A

4 cranial nerves exit medulla
4 cranial nerves exit pons
4 exit above pons

35
Q

What determines the location of motor and sensory columns?

A

Development

36
Q

What do cranial nerve nuclei lie adjacent to during embryological development?

A

Ventricular system

37
Q

Which nuclei develop from the alar plate?

A

Sensory

38
Q

Which nuclei develop from the basal plate?

A

Motor

39
Q

What is the relationship of the alar and basal plates in the spinal cord?

A

Alar plate becomes dorsal horns

Basal plate becomes ventral horns

40
Q

What does the fourth ventricle do to the dorsal nuclei during development?

A

Pushes them laterally

41
Q

How are nuclei positioned in the brainstem?

A

In columns

42
Q

How are cranial nerve nuclei grouped?

A

Based on similar functions

43
Q

Where are motor nuclei located?

A

Closer to midline

44
Q

Where are sensory nuclei located?

A

Laterally

45
Q

How many motor columns are there, and what are they?

A

3

  • General somatic motor
  • Branchial motor
  • General visceral
46
Q

How many sensory columns are there, and what are they?

A

3

  • General and special visceral
  • General somatic
  • Special somatic
47
Q

Which columns are closer to the midline?

A

Motor

48
Q

Which columns are located laterally?

A

Sensory

49
Q

What is the reticular formation continuous with?

A

Rostrally, with certain nuclei in thalamus

Caudally, with intermediate grey of spinal cord

50
Q

What are the rostral functions of the reticular formation?

A

Higher cortical function

- Maintain alert conscious state

51
Q

Where is the rostral reticular formation?

A

Midbrain and upper pons

52
Q

What are the caudal functions of the reticular formation?

A

Many tasks of spinal cord but with greater complexity

Work together with cranial nerve nuclei and spinal cord to carry out important motor reflexes and autonomic functions

53
Q

Where is the caudal reticular formation?

A

Pons and medulla

54
Q

How does the reticular formation modulate forebrain activity rostrally?

A

Via

  • Ascending reticular activating system
  • Long projection systems
55
Q

What are long projection systems defined by?

A

Neurotransmitter

56
Q

What are some long projection systems?

A

Noradregernic from locus ceruleus
Dopaminergic from substantia nigra
Serotonergic via dorsal raphe nucleus
Cholinergic

57
Q

What does a lesion in the midbrain mean?

A

Coma

58
Q

What does the ventrolateral medullary reticular formation do?

A

Regulate visceral functions CN X

  • GI responses
    • Swallowing
    • Vomiting
  • Respiratory activities
    • Rhythm
    • Coughing
    • Hiccupping
    • Sneezing
  • Cardiovascular responses
59
Q

What are the lateral medullary anf pontine reticular formations important for?

A

Chewing

60
Q

What is the region surrounding facial nucleus important for?

A

Crying

Smiling

61
Q

Which major pathways traverse the brainstem?

A

Dorsal column-medial lemniscus system
Anterolateral system
Corticospinal system

62
Q

What are the ascending pathways in the brainstem?

A

Dorsal column-medial lemniscus system

Anterolateral system

63
Q

What are the descending pathways in the brainstem?

A

Corticospinal system

64
Q

Describe the dorsal column-medial lemniscus system

A
3 neurons
Fine touch
- Tactile
- Vibration
Crosses in medulla
Travels medially for the most but veers laterally in midbrain
65
Q

Describe the anterolateral system

A
3 neurons
Pain
Crosses in spinal cord
Travels laterally
Gets close to dorsal column-medial lemniscus pathway in midbrain
66
Q

Describe the corticospinal tract

A

2 neurons
Motor control
Crosses at pyramidal decussation at boundary of brainstem
Upper motor neuron synapses with lower motor neuron in spinal cord

67
Q

What do the dorsal aspects of the brainstem contain?

A

Cranial nerve nuclei

Reticular formation

68
Q

What do the ventral aspects of the brainstem contain?

A
Corticospinal tracts
Midbrain
- Cerebral peduncles
- Substantia nigra
- Red nuclei
Pons
- Cerebellar nuclei
- Middle cerebellar peduncle
Medulla
- Inferior olivary nuclei