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Medicine > Brainstem > Flashcards

Brainstem Flashcards

1
Q

what are the three types of function of the brainstem

A
  1. acts as a conduit- ascending/descending pathways
  2. cranial nerve functions via brainstem nuclei
  3. integrative and modulatory functions through reticulum
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2
Q

what does the brainstem exert neuronal influence over

A

heart rate
respiration
antigravity and postural muscles
eye movement
head tracking
lower motor neuron excitation
autonomic activation
arousal
sleep
vomiting

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3
Q

what is the location of the brainstem

A

housed by the POSTERIOR CRANIAL FOSSA

anterior there is:
clivus
nerves and vessels

posterior:
cerebellum and attachments

inferior:
foramen magnum
spinal cord

superior:
tentorium cerebelli
diencephalon

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4
Q

why does the brainstem need a central location

A

-takes info to and from the cortex
-takes info to and from cerebellum (to correct intended movements)
-cranial nerves

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5
Q

what are the three segments of the brainstem

A

midbrain
pons
medulla

the three segments have functional differences

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6
Q

name the neuronal types found in the internal part of the brainstem

A

tegmentum- 3 different kinds- runs theentire length of brainstem
tectum
substantia nigra
crus cerebri- base of pedicles top of midbrain
cerebral aqueduct
periaqueductal grey matter (around aqueduct)- MODULATE PATHWAY FOR INCOMING PAIN

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7
Q

what happens in the pons in the corticospinal tract

A

the fibers are broken into many bundles
before descending at the pyramids

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8
Q

where do the lateral corticospinal tract terminate

A

lower motor neurons in the anterior horn of the spinal cord

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9
Q

where do the anterior corticospinal tract terminate

A

LMNs

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10
Q

what does a brainstem lesion of the lateral corticospinal tract produce

A

contralateral UMNs signs

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11
Q

what happens to the pathway of the corticobulbar descending tract

A

carries motor info from motor cortex, go through internal capsule and branch off and innervate different motor nuclei in brainstem
these motor nuclei control facial and neck muscles
innervation is BILATERAL, decussation occurs at the level of the nucleus

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12
Q

what does a brainstem lesion of the corticobulbar tracts produce

A

usually ipsilateral
effects dependant on where the lesion is

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13
Q

what are the tracts that have descending pathways, where info is generated from the brainstem and not the cortex. they have sensory info coming to them via other pathways (extrapyramidal pathways- NOT CORTOSPINAL TRACTS)

A

Rubrospinal tract
Tectospinal tract
Vestibulospinal
Reticulospinal

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14
Q

describe the rubrospinal tract

A

subconscious coordination effect
contralateral pathway
upper limb coordination

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15
Q

describe the tectospinal tract

A

connects to cervical spinal cord- neck musculature
from superior colliculus (VISUAL oriented control of neck muscles)- inferior are involved in SOUND

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16
Q

describe the vestibulospinal pathway

A

2 pathways
LATERAL vestibular nuclei- arms (ipsilateral excitatory to extensors, inhibitors to flexors- so when fall you put your arms out)
MEDIAL- head (bilateral neck muscles, so move head away from falling)
info from vestibular cochlear apparatus, vestibular pathway

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17
Q

describe the reticulospinal pathway

A

mass of dendritic connections
pontine and medullary reticular formations

allow you to stay upright, spring in step

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18
Q

what are the effects of a brainstem lesion in the medial lemniscal pathway

A

contralateral loss of JPS and discriminating touch

19
Q

what are the effects of a lesion in the spinal lemniscal pathway (spinothalamic tract)

A

produces a contralateral loss of pain and temperature sensation

20
Q

what are the effects of a lesion in the spinocerebellar tract

A

ataxia
ipsilateral defect

21
Q

what is ataxia

A

inability to coordinate self
==cerebellar problem
therefore know it is ipsilateral

22
Q

what are the reticulum and what are their functions

A

they are found throughout the brainstem
found in the central tegmentum
diffuse network of nuclei- regulate activity
work predominately in groups of NT related networks

important in regulation of pain sensation, arousal (sleep) of cortex and modulation of descending motor output

23
Q

what is the final layout of the brainstem in regards to sensory and motor nuclei and how it compares to the spinal cord layout

A

as the tectum increases-enlarges, it pushes the nuclei from a ventral-dorsal order to a medial-lateral arrangement (what is found in the brainstem)

24
Q

what is the organisation of the the cranial nerve nuclei

A

three lateral sensory columns of nuclei
three Medial Motor columns

25
Q

are cranial nerves mixed

A

they can be either sensory, motor, mixed

26
Q

which cranial nerves are sensory

A

1, 2, 8

27
Q

which cranial nerves are motor

A

3,4,6,11,12

28
Q

which cranial nerves are mixed

A

5, 7, 9, 10

29
Q

what rule do the cranial nerves follow

A

rule of 4
4 in or ABOVE midbrain
4 in pons
4 in medulla

30
Q

what does the oculomotor nucleus connect to and its function

A

oculomotor nerve 3
extraocular eye muscles
EXCEPT superior oblique and lateral rectus

31
Q

what does trochlear nucleus connect to and its function

A

trochlear nerve
control superior oblique muscle of eye

32
Q

what does abducens nucleus connect to and its function

A

abducens nerve
control lateral rectus muscle of the eye

33
Q

what dies the hypoglossal nucleus connect to and its function

A

hypoglossal nerve
controls tongue muscle (deviation towards lesion side)

34
Q

look at cranial nerves and structures they go to!

A
35
Q

are there non-cranial nerve nuclei

A

yes found in different brainstem levels

midbrain
-medial geniculate
-red nucleus
-substantia nigra
-superior colliculus
-inferior colliculus
-reticular formation

pons
-pontine nuclie
-reticular formation

medulla
-olive
-vital centres
-non-vital centres
reticular formation

36
Q

what are the clues to diagnosing brainstem localisation lesion

A

midbrain– eye movement
pons– mastication
medulla– swallowing

brainstem lesions usually produce ipsilateral cranial nerve defects

37
Q

what are some signs there are lesions affecting CONDUCTION

A

weakness
loss of pain, temp
ataxia
loss of JPS and vibration

38
Q

what are some signs there are lesions affecting cranial nerve functions

A

eye muscle weakness
so sensation on face
autonomic dysregulation
problems speaking or swallowing
vertigo
changes in taste and hearing

39
Q

what are some signs there are lesions affecting the reticular function

A

uncontrolled movements-choria
tremor
ataxia
autonomic dysfunction
lethargy
locked in syndrome

40
Q

what is locked in syndrome

A

PONTINE lesion disrupting all motor traffic to spinal cord and face
sparing midbrain EYE muscle control

41
Q

what is chorea

A

writhing movements

42
Q

how do clues help with diagnosis

A

signs of both sides (traffic going up and down)
symptoms above and below lesion
look at cranial nerves are involved-gives level in brainstem
work out if medial, lateral, bilateral
if ipsilateral– sympathetic, LMN cranial nerve, limb ataxia
if contralateral– limb/body UMN, loos of pain, temp, fine touch, proprioception

43
Q

what is lateral medullary syndrome

A

wallenberg syndrome
medullary lesions starved of blood
characteristics above and below
ataxia on right side (therefore lesion on that side)
lose of pain, dysphagia and temp on other side
ptosis and small pupil also ipsilateral

Medicine (54 decks)

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