OCB03-2006 Flashcards

1
Q

What makes up the hindbrain?

A

Pons

Cerebellum

Medulla

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2
Q

What is an alternative name for the midbrain?

A

Mesencephalon

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3
Q

What makes up the brainstem?

A

Midbrain and hindbrain

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4
Q

What is the diencephalon made up of?

A

Thalamus

Hypothalamus

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5
Q

What is the reticular formation responsible for and where is it found?

A

Arousal, cardiovascular and respiratory centres/roles

Found at level of medulla

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6
Q

Where is the raphe nucleus found?

A

Midline of brainstem

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7
Q

Where is the locus coeruleus nucleus found and what is its significance?

A

At level of pons in brainstem

Centre of noradrenergic pathways

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8
Q

What are the raphe and locus coeruleus nuclei mainly responsible for?

A

Mood

Sleep

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9
Q

Where is the substantia nigra found?

A

At level of midbrain, ventromedially

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10
Q

What is the function of the substantia nigra and its clinical importance?

A

Movement control

Loss of dopaminergic neurons => Parkinson’s disease

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11
Q

Where is the centre of all dopaminergic pathways?

A

Ventral tegmental area and substantia nigra

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12
Q

How does the dorsal surface of the brainstem differ at the level of the closed and open medulla?

A

Closed medulla = rounded

Open medulla = flaps/concave

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13
Q

Why is there a “closed” and “open” medulla?

A

Medulla becomes open when the central canal opens superiorly into the fourth ventricle

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14
Q

Describe the gracile fasciculi.

A

Ascending pathways for fine touch and conscious proprioception or vibration

Synapse at level of closed medulla with gracile nuclei

Dorsal and more medial than cuneate fasciculi

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15
Q

Describe the cuneate fasciculi.

A

Ascending pathways for fine touch and conscious proprioception or vibration

Synapse at level of closed medulla with cuneate fasciculi

Doral and more lateral than gracile fasciculi

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16
Q

Describe the medullary pyramids.

A

Contain axons of corticospinal tract (motor)

Main pathway in voluntary control of limbs

Ventral

Axons cross over at level of closed medulla = “decussation of pyramids”

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17
Q

What fills the central canal of the medulla?

A

CSF

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18
Q

Which cranial nerve nuclei are found at the level of the closed medulla?

A

Accessory nerve nuclei medially

Trigeminal nerve spinal nuclei laterally

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19
Q

What is the hole found dorsally at the level of the pons?

A

Cerebral aqueduct

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20
Q

What is the function of the axons running horizontally at the level of the pons?

A

Pontocerebellar fibres

Take motor info from pontine nuclei to cerebellum through basilar pons and middle cerebellar peduncle

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21
Q

Where do corticobulbar tracts originate and terminate?

A

Cortex to cranial nerve motor nuclei

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22
Q

What is the periaqueductal grey and why is it important?

A

Grey matter around the beginning of the cerebral aqueduct

Important in pain control

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23
Q

What is the importance of the superior and inferior colliculi?

A

Responsible for reflex eye movement (connected to extraocular muscles)

Superior colliculi = in response to visual stimuli

Inferior colliculi = in response to sound

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24
Q

What are the structures that indicate the position of the midbrain?

A

2 bumps = superior and inferior colliculi

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25
What are the cerebral peduncles?
2 big blocks of white matter ventrolaterally at level of midbrain Mainly descending axons
26
What is the position of the substantia nigra relative to the cerebral peduncles?
Medial
27
What gives the substantia nigra its name?
Neuromelanin
28
Is the substantia nigra grey or white matter?
Grey matter
29
Which part of the autonomic system has associations with cranial nerves?
Parasympathetic
30
What is the clinical significance of the brainstem housing cranial nerve nuclei?
Cranial nerve testing can be used to look at brainstem integrity
31
What is the function of the first cranial nerve?
Carries special sensory info responsible for olfaction/smell
32
Describe how information about smell reaches the brain.
Olfactory neurons present in olfactory epithelium and synapse within the olfactory bulbs Second-order neurons extend through olfactory tract to olfactory cortex
33
What is the function of the second cranial nerve?
Vision
34
Where is the optic nerve?
Area between retina and optic chiasm
35
What cells does the optic nerve arise from?
Retinal ganglion cells which project axons back as optic nerve to the optic chiasm
36
Describe how visual information reaches the brain.
Optic nerve extends from retina to optic chiasm Axons of nasal retinae decussate, temporal retinae axons stay ipsilateral at optic chiasm Axons travel as optic tract to lateral geniculate nucleus Most axons synapse in lateral geniculate nucleus of thalamus to travel to visual cortex
37
Why do only the nasal retinae axons decussate?
Allows formation of stereoscopic image
38
What will a lesion of one optic nerve cause?
Loss of sight from that eye
39
What will a lesion of one optic tract cause?
Loss of half the visual field in each eye
40
Where does the optic tract start?
Optic chiasm
41
What are the functions of the oculomotor nerve?
Somatomotor to 4 extraocular muscles Parasympathetic to pupillary muscles (light reflex) and ciliary muscles (accommodation reflex)
42
Where does the parasympathetic aspect of C.III arise from?
Edinger-Westphal nucleus/accessory oculomotor nucleus
43
Which is the thickest cranial nerve?
Trigeminal nerve (C.V)
44
What is the function of the trochlear nerve?
Innervate superior oblique muscle To depress and laterally move eyeball
45
What gives the trochlear nerve its name?
Innervates the superior oblique muscle which has a tendon running through a small ligamentous "pulley" called the trochlear
46
What is the function of the abducens nerve?
Innervates lateral rectus To abduct the eyeball (move laterally)
47
If both eyes are looking to the left, which nerves will be acting on each eye?
Left eye will be abducting => abducens (C.VI) Right eye will be adducting => oculomotor (C.III)
48
What are the general functions of the trigeminal nerve?
Somatosensory from almost all head and neck Motor to muscles of mastication
49
Describe the parts of the trigeminal nucleus responsible for different sensory information.
Spinal nucleus = pain or temperature Principal/chief nucleus = fine touch and conscious proprioception Mesencephalic nucleus = unconscious proprioception
50
What sensory info is the spinal nucleus responsible for?
Pain and temperature
51
What sensory info is the principal/chief nucleus responsible for?
Fine touch and conscious proprioception
52
What sensory info is the mesencephalic nucleus responsible for?
Unconscious proprioception
53
What is the path of information from the trigeminal nucleus to the somatosensory cortex?
Travels up to synapse at the ventral postero-medial nucleus of the thalamus
54
What do each of the trigeminal branches supply (generally)?
Ophthalmic/V1 = forehead and upper parts of orbit Maxillary/V2 = inferior parts of orbits and cheeks Mandibular/V3 = lower jaw and tongue
55
What are the general functions of the facial nerve?
Somatosensory to eardrum and skin of external auditory meatus Special sensory = taste to anterior 2/3 tongue, palate Motor to muscles of facial expression Parasympathetic to all salivary glands except parotid, lacrimal glands
56
What is another term for muscles of facial expression?
Mimetic muscles
57
What causes Bell's palsy?
Lesion of lower motor neuron of facial nerve (after leaving motor nucleus)
58
What is Bell's palsy?
Lesion of lower motor neuron of facial nerve Causing paralysis of one side of the face
59
What is another term for Bell's palsy?
Peripheral facial palsy
60
What is central facial palsy caused by?
Lesion of upper motor neuron of facial nerve (corticobulbar tract)
61
What is central facial palsy?
Lesion of upper motor neuron of facial nerve Causing paralysis of lower part of half the face
62
What is another name for central facial palsy?
Corticobulbar palsy
63
Why does an upper facial motor neuron lesion only paralyse the lower part of half the face?
Facial nerve is paired so won't affect other side of face Upper parts of face receive info from both hemispheres so allows for compensation
64
What are the functions of the vestibulocochlear nerve?
Vestibular branch monitors balance, position, movement Cochlear branch monitors hearing
65
Where does the cochlear branch of C.VIII arise from?
Organ of Corti
66
Where does the vestibulocochlear nerve enter the brainstem?
Pontine angle (junction of pons, medulla and cerebellum)
67
What are the functions of the glossopharyngeal nerve?
Special sensory = taste to posterior 1/3 tongue Sensory to posterior 1/3 tongue and oropharynx Motor to muscles of upper pharynx Parasympathetic to parotid gland Visceral sensory in measuring blood pCO2 and pH via carotid body
68
What are the functions of the vagus nerve?
Somatosensory to mucous membranes of laryngopharynx, larynx, upper trachea Visceral sensory to trachea, lungs, carotid sinus, abdominal veins, gut Somatic motor to lower pharynx and upper oesophageal muscles Parasympathetic to cardiac muscles, smooth muscle of GI tract, trachea and bronchi
69
Where does the spinal accessory nerve arise?
C1 to C4/5
70
What are the functions of the accessory nerve?
Innervates muscles associated with head and shoulder movement Sternocleidomastoid = turning and depressing head Trapezius = shrugging
71
What is the function of the hypoglossal nerve?
Somatomotor to intrinsic muscles and most extrinsic muscles of tongue
72
How does the hypoglossal nerve arise?
As a series of rootlets from the medulla
73
What are the two special nuclear groups in the brainstem formed by more than one cranial nerve?
Nucleus ambiguus Nucleus tractus solitarius
74
What cranial nerves contribute to the nucleus ambiguus and what is the function of this nucleus?
Glossopharyngeal and vagus nerves Motor supply to larynx, pharynx and upper oesophagus Important in reflexes like swallowing, vomiting, phonation and coughing
75
What cranial nerves contribute to the nucleus tractus solitarius and what is the function of this nucleus?
Facial, glossopharyngeal and vagus nerves Visceral sensory supply from tongue, carotid sinus, GI tract, trachea and bronchi Important in taste, chemoreception, gut distention and blood pressure monitoring
76
Which special nucleus can be referred to the "main chemoreceptive centre of the brain"?
Nucleus tractus solitarius