Organisation of the Brainstem and cranial nerves Flashcards
1
Q
what are the 3 categories of the brainstem function
A
- cranial nerve functions
- conduit functions
- integrative functions
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
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
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
5
Q
what is the midbrain divided into
A
- superior colliculus
- inferior colliculus
- cerebral peduncle
6
Q
what does the superior colliculus do
A
- controls eye movements and direction of visual attention
7
Q
what does inferior colliculus do
A
- this is a component of the auditory pathway
8
Q
what does the cerebral peduncle do
A
- fibre tracts descending from cortex to brainstem and spinal cord respectively
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
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
11
Q
what 2 midbrains
A
- rostral midbrain
- caudal midbrain
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
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
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
15
Q
what is the periaqueductal gray involved in
A
- involved in descending pain control and regulation of autonomic functions
16
Q
what are the two different types of pons
A
rostral pons and caudal pons
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
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
19
Q
where is the widest part of the 4th ventricle
A
- the junction at the pons and medulla
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
where do cells using serotonin arise from
sermoning form the midline raphe nucleic
26
where do cell using acetylcholine arise from
midbrain and pons- lateral tegmenjtum and penculopontien nucleus and the forembrain
27
what is the midbrain functionally associated with
- auditory, visual and pupillary reflexed and with eye movement
- associated with input from cranial nerves II- IV and VIII
28
what is the pons functionally associated with
- 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
where do nerves at the brainstem join
- nerves VI and VIII joint he brainstem at the pontomedullary junction
30
what is the medulla functionally associated with
- equlibrium and audition, deglutition, coughing, vomiting, salivation, tongue movement, respiratory and cardiovascular function
- cranial nerves VIII- XII
31
what do second order neurones receive input from
- they receive input from peripheral sensory neurones
32
where are the primary sensory ganglia found
- found in the peripheral sensory ganglia
33
what is the sulcus limitans
- 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
where are the 2nd order sensory neurones found
- lateral to the sulcus limitans
35
what are the brainstem motor neurones
- they are medial to the sulcus limitans
36
what is most lateral
somatic sensory nucleic
37
what is most medial
somatic lower motor neurones
38
what nucleic is closest to the sulcus limitans
- visceral nuclei
| -
39
what is the significance of brainstem organisation
- 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
describe the visual reflex
afferent arch - CNII
efferent arc - CNIII
- brainstem area - midbrain
41
describe the accommodation reflex
afferent arc - CNII
efferent arc - CNIII
brainstem area - midbrain
42
describe the doll's eye reflex
Afferent arc - CN VIII
efferent arc - CNIII, IV, VI
brainstem area - Midbrain/pons
43
describe the jaw jerk reflex
Afferent arc - CN V3
efferent arc - CN V
brainstem area - pons
44
describe the blink reflex
Afferent arc - CN V1, CN VIII CNII
efferent arc - CN VII
brainstem area - pons
45
describe the gag reflex
Afferent arc - CNIX
efferent arc - CN X
brainstem area - medulla
46
what is the blood supply to the brain
- vertebral basilar posterior cerebral artery system
47
where do the vertebral arteries fuse
- they fuse to form the basilar this runs on the ventral surface of the pons
48
what do the PICA and AICA supply
- they supply parts of the brainstem and then run around to get to the cerebellum or other structures
49
where do vertebral and posterior inferior cerebellar arteries occlusion do
- they effect the medial and lateral medullary syndromes that are caused by occlusion
