Organisation of the Brainstem and cranial nerves Flashcards

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1
Q

what are the 3 categories of the brainstem function

A
  1. cranial nerve functions
  2. conduit functions
  3. integrative functions
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2
Q

what are the cranial nerve functions

A
  • brainstem contains function centres that are associated with 11 of the 12 pairs of cranial nerves
  • they have sensory and motor functions of the head are carried out by these nuclei
  • parasymapthric output originates and special sensory input is processed in these and associated brainstem nuclei
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3
Q

describe what the conduit functions do

A
  • it contains the ascending and descending pathways going to and from the spinal cord carrying sensorimotor information
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4
Q

describe what the integrative functions do

A
  • respiratory and cardiovascular activities
  • the maintenance of consciousness, sleep and arousal that occur via the reticular formation that runs throughout the length of the brainstem
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5
Q

what is the midbrain divided into

A
  • superior colliculus
  • inferior colliculus
  • cerebral peduncle
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6
Q

what does the superior colliculus do

A
  • controls eye movements and direction of visual attention
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7
Q

what does inferior colliculus do

A
  • this is a component of the auditory pathway
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8
Q

what does the cerebral peduncle do

A
  • fibre tracts descending from cortex to brainstem and spinal cord respectively
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9
Q

Describe the structure of pons

A
  • the cerebellar peduncles attach the caudal pons to the cerebellum while throughout the floor of the 4th ventricle is found medially
  • the superior cerebellar peduncle is in the rostral pons, is it a major output from cerebellum
  • the middle cerebellar peduncle carriers afferent input from the pontine nuclei
  • the inferior penduncle is the pathway for inferior olivary nucleus and other inputs to the cerebellum
  • basal pons - this is the bridge for which the pons is named, it is composed of transverse and descending fibres and pontine nuclei
  • the corticopontine fibres input to these nuclei
  • they then send crossing projections to the contralateral cerebellar cortex - enter via the MCP
  • CST axons continue thought the basal pons
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10
Q

describe the structure of the medulla

A
  • medially the floor of the 4th ventricle continues at the rostral or open medulla until it closes and forms the central canal
  • pyramid - the corticospinal tract in the medulla is compacted into two wedge shaped
  • the pyramidal decussation makes the junction of the medulla with the spinal cord
  • the olive is a bulge in the rostral medulla on the side of the pyramids containing the inferior olivary nucleus - this is an important projection nucleus to the cerebellum
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11
Q

what 2 midbrains

A
  • rostral midbrain

- caudal midbrain

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12
Q

what does the rostral midbrain do

A
  • it is a motor nucleus linked to cerebellar circuitry through the inferior olivary nucleus
  • the substantial nitra is important in motor function and is part of the basal ganglia
  • its compact part has dopmaingerigc neurones that degernate in Parkinson’s diseases
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13
Q

what does the caudal midbrain do

A
  • a small group of cells of the pontine nuclei can be found here in the cerebral peduncle as well as corticospinal axons
  • the corticopontine and cortiobulbar (to the Brainstem) fibres here
  • cerebellar output fibres of the SCP cross travelling rostrally to the red nucleus and thalamus
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14
Q

what are the medial longitudinal fascicles do

A
  • they connect the brainstem gaze centres and the vestibular system allows coordination of eye movements and maintenance of gaze with head movement
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15
Q

what is the periaqueductal gray involved in

A
  • involved in descending pain control and regulation of autonomic functions
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16
Q

what are the two different types of pons

A

rostral pons and caudal pons

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17
Q

describe the rostral pons

A
  • the superior cerebellar peduncle is prominent in the dorsal brainstem at this level
  • the 4th ventricle is formed from the cerebral aqueduct with most caudal periquaeductal gray surrounding it ventrally
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18
Q

describe the caudal pons

A
  • the cerebellum is attached physically here mainly by the middle cerebellar peduncles
  • deep cerebellar nuclei contribute efferent axons to the SCP surrounded by the cerebellum at this level
  • the 4 ventricle is wide
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19
Q

where is the widest part of the 4th ventricle

A
  • the junction at the pons and medulla
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20
Q

what are the two medulla

A
  • rostra medulla

- caudal medulla

21
Q

describe the structure of the rostral medulla

A
  • this is the part of the medulla that has the inferior olivary nucleus with crossing internal arcuate fibres entering into the inferior cerebellar peduncle
  • at the upper part of it there is the 4th ventricle which cis more caudally forms the central canal
  • the spinal nucleus of the trigeminal nerve receives pain and temperature information from the head
22
Q

describe the structure of the caudal medulla

A
  • extends from the pyramid decussation to the start of the 4th ventricle
  • this part of the medulla includes - the dorsal column nuclei - this is made up of the nucleus gracilis and nucleus cuneatus
  • from these axis of second order neurones cross as more internal arcuate fibres and then travel in the medial reminisces
  • spinothalamic axons are laterally placed similar to their position in the spinal cord
23
Q

what does the caudal medulla contain in it

A
  • the dorsal column nuclei

- this is made up of the nucleus gracilis and nucleus cuneatus

24
Q

where do cells using noradrenaline arise from

A
  • locus cerulean in the rostral pons
25
Q

where do cells using serotonin arise from

A

sermoning form the midline raphe nucleic

26
Q

where do cell using acetylcholine arise from

A

midbrain and pons- lateral tegmenjtum and penculopontien nucleus and the forembrain

27
Q

what is the midbrain functionally associated with

A
  • auditory, visual and pupillary reflexed and with eye movement
  • associated with input from cranial nerves II- IV and VIII
28
Q

what is the pons functionally associated with

A
  • functions are mastication, eye movement, facial expression, blinking and salivation and equilibrium and adutiton
  • cranial nerves V- VII
  • nerves VI and VIII joint he brainstem at the pontomedullary junction
29
Q

where do nerves at the brainstem join

A
  • nerves VI and VIII joint he brainstem at the pontomedullary junction
30
Q

what is the medulla functionally associated with

A
  • equlibrium and audition, deglutition, coughing, vomiting, salivation, tongue movement, respiratory and cardiovascular function
  • cranial nerves VIII- XII
31
Q

what do second order neurones receive input from

A
  • they receive input from peripheral sensory neurones
32
Q

where are the primary sensory ganglia found

A
  • found in the peripheral sensory ganglia
33
Q

what is the sulcus limitans

A
  • this is formed because of the way the neural tube opens at the level of the 4th ventricle
  • this is visible on transverse sections
34
Q

where are the 2nd order sensory neurones found

A
  • lateral to the sulcus limitans
35
Q

what are the brainstem motor neurones

A
  • they are medial to the sulcus limitans
36
Q

what is most lateral

A

somatic sensory nucleic

37
Q

what is most medial

A

somatic lower motor neurones

38
Q

what nucleic is closest to the sulcus limitans

A
  • visceral nuclei

-

39
Q

what is the significance of brainstem organisation

A
  • neurones with similar functions are brought into close proximity to reduce the amount of neural wiring needed
  • if there is a lesion different functions are affected depending on whether the lesion is lateral or near the midline
40
Q

describe the visual reflex

A

afferent arch - CNII
efferent arc - CNIII
- brainstem area - midbrain

41
Q

describe the accommodation reflex

A

afferent arc - CNII
efferent arc - CNIII
brainstem area - midbrain

42
Q

describe the doll’s eye reflex

A

Afferent arc - CN VIII
efferent arc - CNIII, IV, VI
brainstem area - Midbrain/pons

43
Q

describe the jaw jerk reflex

A

Afferent arc - CN V3
efferent arc - CN V
brainstem area - pons

44
Q

describe the blink reflex

A

Afferent arc - CN V1, CN VIII CNII
efferent arc - CN VII
brainstem area - pons

45
Q

describe the gag reflex

A

Afferent arc - CNIX
efferent arc - CN X
brainstem area - medulla

46
Q

what is the blood supply to the brain

A
  • vertebral basilar posterior cerebral artery system
47
Q

where do the vertebral arteries fuse

A
  • they fuse to form the basilar this runs on the ventral surface of the pons
48
Q

what do the PICA and AICA supply

A
  • they supply parts of the brainstem and then run around to get to the cerebellum or other structures
49
Q

where do vertebral and posterior inferior cerebellar arteries occlusion do

A
  • they effect the medial and lateral medullary syndromes that are caused by occlusion