brainstem and cranial nerves I Flashcards

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1
Q

where is the brainstem located?

A

between the forebrain and spinal cord

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2
Q

what foes the forebrain divide into?

A

telencephalon

diencephalon

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3
Q

what makes up the brainstem?

A

midbrain
pons
medulla

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4
Q

what is the oldest part of the brain evolutionarily?

A

brainstem

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5
Q

what are the functions of the midbrain?

A

processes visual, auditory data.
Maintains consciousness
Also reflexive somatic motor responses bc of the colliculi on top of the midbrain)

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6
Q

what are the functions of the pons?

A

relays sensory information to cerebellum and thalamus. Subconscious somatic and visceral motor centres

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7
Q

what are the functions of the medulla?

A

relays sensory information to thalamus. Contains autonomic centres for regulation of visceral function

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8
Q

name the main functions of the brainstem?

A

conduit - long tracts to or from spinal cord pass through brainstem

cranial nerve function - sensory input/motor output for the head plus parasympathetic motor output. Cranial nerves carry special senses, brainstem coordinates reflexes involving them

integration centres - relays info to cerebellum

reticular formation - interconnected nuclei throughout brainstem

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9
Q

what do the nuclei of reticular formation mediate?

A

o Autonomic control of important respiratory/cardiovascular reflexes and other behaviours e.g. swallowing, sneezing
o Somatic/autonomic modulation via descending pathways
o Important in regulation of consciousness.

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10
Q

what is the brainstem?

A

an extension and elaboration of the spinal cord

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11
Q

at what spinal level does the spinal cord become the brainstem?

A

C2

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12
Q

what happens to sensory and motor nuclei when they move from the spinal cord to the brainstem?

A

Sensory nuclei that were dorsal in the spinal cord move laterally, motor nuclei move medially

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13
Q

what is found in the dorsal part of the brainstem?

A

cranial nerve nuclei found here and sensory reflex centres

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14
Q

what is the name for the dorsal part of the brainstem?

A

tectum

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15
Q

what is the name for the middle part of the brainstem?

A

tegmentum

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16
Q

what does the tegmentum contain?

A

ascending pathways and reticular formation

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17
Q

what does the ventral part of the brainstem contain?

A

descending motor pathways e.g. corticospinal and corticobulbar tracts

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18
Q

where are the superior and inferior colliculus found?

A

in the midbrain

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19
Q

where is the cerebral peduncle found?

A

in the midbrain

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20
Q

what does the cerebral peduncles contain?

A

tracts descending from the cortex through the brainstem to the spinal cord (corticospinal).

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21
Q

what are the functions of the different regions of the pons?

A
  • Superior: main output path from the cerebellum to the midbrain.
  • Middle: afferent input from pontine nucleus (motor activity).
  • 4th ventricle (found medially).
  • Basal pons: bridge composed of transverse and descending fibres
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22
Q

from what surface can you see the cranial nerves?

A

ventral

23
Q

how many cranial nerves are associated with the brainstem?

A

11

24
Q

what cranial nerves are found in the midbrain?

A

II - IV

25
Q

what are the main functions of the the midbrain?

A

auditory, visual, pupillary reflexes as well as eye movements

26
Q

what cranial nerves are found in the pons?

A

V - VIII

27
Q

what are the main functions of the pons?

A

mastification, eye movements, facial expression, taste, blinking, lacrimation, audition, salivation.

28
Q

what cranial nerves are found in the medulla?

A

VIII - XII

29
Q

what are the main functions of the medulla?

A

equilibrium, audition, deglutition, salivation, taste, respiration, circulation, Gi function, neck and shoulder movements, tongue movements, coughing, vomiting

30
Q

what cranial nerves are purely sensory?

A

I, II and VIII

31
Q

what cranial nerves are pure motor nerves?

A

III, IV, VI, XI, XII

32
Q

what cranial nerves are mixed sensory and motor nerves?

A

V, VII, IX and X

33
Q

what are the 3 types of motor nuclei and what do they do?

A

o Somatic motor nuclei project to skeletal muscle (eye muscles and tongue)
o Branchial motor nuclei project to muscles derived from branchial arches (craniofacial structures)– movement of jaws (V), facial expression (VII), motor to larynx and pharynx (X) and neck and shoulder muscles (XI)
o Visceral motor nuclei: pre-ganglionic parasympathetic fibres

34
Q

what type of nucleus does the hypoglossal nerve have?

A

somatic motor

35
Q

what does the hypoglossal nerve do?

A

innervates internal and external tongue muscles

36
Q

what type of nucleus does the spinal accessory nerve have?

A

pure branchial motor

37
Q

what does the spinal accessory nerve innervate?

A

SCM and trapezius

38
Q

where does the spinal accessory nerve enter and exit the skull?

A

enters via foramen magnum

exits via jugular foramen

39
Q

what are the motor neurons that give rise to the accessory nerve?

A

a separated fragment of the long column of the nucleus ambiguus. They arise from C3-C5

40
Q

what nerves arise from the nucleus ambiguus?

A

XI and X

41
Q

what does the vagus innervate?

A
  • Branchial motor innervation of the palate, pharynx and larynx is conveyed via CN X
  • Parasympathetic outflow to the heart and digestive system arises from the dorsal motor nucleus of the vagus (and parasympathetic part of n. ambiguous)
  • Afferents from the lungs and gut travel in the vagus nerve mediating parasympathetic reflexes, swallowing, coughing, retching etc.
42
Q

what does damage to the vagus nerve lead to?

A

difficulty swallowing and vocalizing – paralysis of vocal cords on the affected side

Poor secretion of gut gluids, salica, stomach acid bc of loss of parasympathetic control

43
Q

is the glossopharyngeal nerve sensory or motor?

A

Mainly sensory BUT parasympathetic secretomotor to the parotid gland (mixed)

44
Q

what are the main functions of the glossopharyngeal nerve?

A

o Detect taste of things in the back of the mouth – conveys to the NTS and stimulates saliva secretion
o Gag reflex – has touch fibres at the back of the mouth to trigger this

45
Q

what does damage to the glossopharyngeal nerve lead to?

A

loss of gag reflex on affected side

46
Q

what are the parts of the vestibulocochlear nerve and what do they each do?

A

o Cochlear – special sense of hearing

o Vestibular - perception of self motion, head position and spatial orientation relative to gravity

47
Q

where does the vestibulocochlear nerve enter the brainstem?

A

ponto-medullary junction

48
Q

what is the main function of the facial nerve?

A

provide motor supply to muscles of facial expression

49
Q

what does the medial longitudinal fasciculus connect?

A

connects cranial nerve nuclei controlling eye movement and vestibular nuclei

50
Q

what is internuclear opthalmoplegia?

A

problem with adduction in the affected eye

51
Q

what causes internuclear opthalmoplegia?

A

o Damage can occur with stroke (unilateral) or multiple sclerosis lesion (often bilateral).

leads to damage to MLF

52
Q

what does the MLF become in the spinal cord?

A

medial vestibulospinal tract (mVST)

53
Q

what does the mVST do?

A

coordinates reflexive head and neck movements to keep eyes stable in space.