Topography of the brain Flashcards

1
Q

describe the formation of the midbrain, hindbrain, forebrain and spinal cord?

A

The forebrain vesicle gives rise not only to the diencephalon but also the cerebral hemispheres.

The midbrain vesicle doesn’t grow very much, whereas the hindbrain vesicle it grows, it falls and forms the pons and medulla in front and the cerebellum at the back.

So the entire brain stem is formed from the midbrain vesicle and then parts of the hindbrain vesicle that form the pons and the medulla.

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2
Q

what happens as soon as the neural tube is formed?

A

it divides into 3 primary vesicles

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3
Q

during what week does the neural tube dovide into 3 primary vesicles?

A

week 4

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4
Q

what do the three primary vesicles divide into during week 5?

A

5 secondary vesicles

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5
Q

what do the 5 secondary vesicles divide into?

A

the adult brain

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6
Q

how does the neural tube cavity persist during vesicle development?

A

the five secondary vesicles are formed the cavity persists within these and it is these cavities that form your ventricles.

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7
Q

what vesicle is found within the cerebral hemisphere?

A

lateral ventricles

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8
Q

what ventricle is found within the diacephalon?

A

3rd ventricle

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9
Q

what is found within the midbrain?

A

cerebral aqueduct

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10
Q

which ventricle is found within the hindbrain vesicle, which gives rise to the pons and medulla in front and the cerebellum at the back

A

fourth ventricle

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11
Q

What are the different ventricles?

A

Lateral ventricles (x2)

III ventricle

Cerebral aquaduct

IV ventricle

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12
Q

Where are the lateral ventricles located?

A

Within cerebral hemispheres

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13
Q

Where is III ventricle located?

A

Within diencephalon

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14
Q

Where is cerebral aquaduct located?

A

Within midbrain

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15
Q

Where is IV ventricle located?

A

Between pons and medulla (in front) and cerebellum (at the back)

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16
Q

Where is CSF found?

A

Inside ventricles and in the subarachnoid space

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17
Q

what are cerebellar peduncles?

A

the structure connecting the cerebellum to the brain stem and the cerebrum

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18
Q

label the different parts of the brainstem?

A

midbrain
pons
medulla

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19
Q

what cranial nerves emerge from the brainstem?

A

Cranial nerves III – XII, tracts from spinal cord, vital centres for eg: cardiorespiratory centre

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20
Q

what are the three functions of the brainstem?

A

Pathway for fibre tracts running between higher & lower centres.

Brainstem nucleii are involved with 10 of the 12 cranial nerves, so innervation of head & neck.

Brainstem centres produce the rigidly programmed automatic behaviours essential for survival.

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21
Q

what does medulla continue as in foramen magnum?

A

At the foramen magnum it becomes the spinal cord.

lum by the inferior cerebellar peduncle.

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22
Q

what is the cavity within the medulla?

A

4th ventricle, located between the medulla and cerebellum.

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23
Q

what are the pyramidal projections beside the 4th ventricle of the the medulla known as?

A

pyramids of the medulla

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24
Q

what are the small projections lateral to the medulla?

A

Lateral to that are little projections that look like olives - called olives

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25
Q

there are a lot of fibres that seem to be criss crossing at the lower part of the pyramids, joining up or going from one pyramid to the other what are they?

A

decussation of the pyramids

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26
Q

how do motor signals travel to the pyramids?

A

These fibres that you have in the ventral part of the medulla that formed this prominence here are nothing but your motor fibres,
motor fibres that originate in the cerebral hemisphere and are carrying the impulses down to your skeletal muscle.
want to move your right upper limb.

The left side of the brain controls the right and therefore motor impulses that have to go to your right upper limb muscle are originating in your left cerebral hemisphere.

They are tracking down from your cerebral hemisphere, down through these fibres just here, down through this part of the pons,
until they reach the medulla that they are going to be sitting within the pyramid.

And at the lower part of the pyramid is where they’re going to cross to the opposite side, so that when they come down
they can leave the spinal cord and then go through the brachial plexus to go to the upper limb muscles on the right.

In order to go to my right upper limb, impulses from my left brain come down from the pyramid of the medulla oblongata,
cross to the right side at the lower part of the pyramids, continues down into the spinal cord, finally leaving it through the ventral horn somewhere between C5 and T1,
goes through the brachial plexus, through the nerves of the brachial plexus and then supplies the muscles of my upper limb

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27
Q

connection of cerebral peduncles?

A

Superior cerebellum connects cerebellum to the midbrain, middle to the pons and inferior to the medulla oblongata.

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28
Q

describe the caudal part of the medulla section?

A

Closed around IV ventricle

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29
Q

desribe the cranial part of the medulla section?

A

Open with IV ventricle posteriorly.

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30
Q

desribe what is found within the white matter of the medulla section?

A

Pyramidal tract
Medial lemniscus
Inferior cerebellar peduncle
Other tracts.

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31
Q

desribe what is found within the grey matter of the medulla section?

A

Cranial n nucleii & inferior olivary nucleus
Nucleii of the Reticular formation (vital centres)
Sensory nucleii (gracile and cuneate)

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32
Q

From the surface of the pons what should you should see arising?

A

cranial nerve 5

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33
Q

what is cranial nerve 5?

A

Cranial nerve five, or trigeminal as we know, mainly carries general sensory information from all of the face.
But there are also motor fibres in its mandibular division.

Cranial nerve five at its origin from the brainstem is quite a chunky nerve.
in gross specimens, while it might sometimes be difficult to identify most of these smaller nerve rootlets, you will always be able to see where cranial nerve five emerges from.

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34
Q

what other cranial nerves arise from the pons?

A

three nerves from the pontomedullary junction.

cranial nerves six (abducent) and cranial nerves seven and eight which come together.
Seven is your facial nerve and eight your vestibulocochlear nerve.

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35
Q

what is located posterior to the pons?

A

IV ventricle

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36
Q

what would you find in the white matter of the pons?

A

1.Middle cerebellar peduncle
2.Medial lemniscus (sensory)
3.Pyramidal tract (motor)

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37
Q

what would you find in the grey matter of the pons?

A

A.Cranial n. nucleii
B.Pontine nucleii
C.Nucleii of Reticular formation

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38
Q

what does the midbrain develop from?

A

mesencephalon.

39
Q

what is the central cavity of the midbrain?

A

cerebral aqueduct.

40
Q

what are surface features of the midbrain?

A

Cerebral peduncle
Superior cerebellar peduncle
Corpora quadrigemina (superior & inferior colliculus)

41
Q

what are Corpora quadrigemina (superior & inferior colliculus)?

A

largest nuclei are the corpora quadrigemina, creating four rounded protrusions on the dorsal surface of the midbrain. The superior colliculi are two visual reflex centers coordinating head and eye movements. The inferior colliculi relay impulses from the auditory center.

42
Q

what nerves emerge from midbrain?

A

Oculomotor (CN III) & Trochlear (CN IV)

IV nerve is the only nerve to originate posteriorly

43
Q

label the different sections of the midbrain?

A
44
Q

what is the function of the cerebral aqueduct within the central cavity of the midbrain?

A

connects III & IV ventricles

45
Q

describe the grey matter in the midbrain?

A

Periaqueductal grey matter with nucleus for III & IV cranial nerves.

46
Q

describe the white matter in the midbrain?

A

White matter with embedded nucleii surrounds the periaqueductal grey matter.

47
Q

what cranial nerves arise from the brainstem?

A

Cranial nerves III – XII, tracts from spinal cord, vital centres for eg: cardiorespiratory centre

48
Q

describe the grey matter of the cerebellum?

A

Cortex on surface
Deep nucleii

49
Q

describe the white matter of the cerebellum?

A

Arbor vitae
Cerebellar peduncles

3rd arrow - flocculonodular lobe

50
Q

what are left and right cerebellum separated by?

A

Vermis

51
Q

what does each hemisphere contain?

A

has an anterior, posterior and flocculonodular lobe

52
Q

what is a flocculonodular lobe?

A
53
Q

what are the two primary functions of the cerebellum?

A

Posture maintenance
Fine tuning motor activity

54
Q

what are the different types of information the cerebellum processes?

A

Information from pyramidal tracts (motor intention of brain)
Information from ipsilateral proprioceptors from periphery
Information from vestibular nucleii re. balance & posture

55
Q

what does the cerebellum do to the information it receives?

A

Calculates best way to coordinate force, direction, extent of muscle contraction to maintain posture prevent overshoot and ensure smooth coordinated muscle contraction.

Sends ‘blueprint’ back to cerebral cortex via superior cerebellar peduncle

56
Q

what is a common abnormality of cerebellum?

A

Ataxia
Finger – nose test
Knee-heel test
Walking in a straight line

57
Q

where is the diencephalon located?

A

Deep within cerebral hemispheres, around the III ventricle.

58
Q

what does diencephalon develop from?

A

diencephalic vesicle (part of forebrain vesicle)

59
Q

what are paired structures of the diencephalon?

A

Thalamus, Hypothalamus (and pituitary), Epithalamus (pineal gland).
All are mainly grey matter.

60
Q

what is 80% of the diencephalon made up of?

A

thalamus

61
Q

what is the function of the thalamus?

A

All sensory information, be they general sensory or special sensory, always synapses within the thalamus.
then the thalamus that triages it and decides which is the most important sensory information that it needs to focus on

62
Q

label the different parts of the brain?

A
63
Q

what does the thalamus mainly contain?

A

groups of nucleii - anterior, medial and lateral group

64
Q

what is the lateral group of nucleii in thalamus responsible for?

A

involved in processing sensory information

65
Q

label the different parts of the left thalamus?

A
66
Q

where is the hypothalamus located?

A

lies below the thalamus separated from it by the hypothalamic sulcus.

67
Q

what is the function of the hypothalamus?

A

main visceral control centre & is essential for overall homeostasis

68
Q

what separates the thalamus from the hypothalamus?

A

a sagittal cut, a little groove or sulcus called the hypothalamic sulcus,it separates the thalamus on top from the hypothalamus below.

69
Q

how is the hypothalamus connected to the pituitary?

A

by the pituitary stalk.

70
Q

where does the pituitary stalk lie?

A

behind that optic chiasm

71
Q

what are homeostatic roles of the hypothalamus?

A

Autonomic Control Centre
Body temperature regulation
Regulation of food intake
Regulation of water balance & thirst
Regulation of sleep-wake cycle
Control of endocrine system functioning

72
Q

what is the blood supply of the brain?

A

The two Internal Carotid Arteries enter the skull through the carotid canal (Foramen Lacerum) to supply the brain.

The two Vertebral arteries (branches of the subclavian artery) also enter the skull through the foramen magnum to supply the brain.

73
Q

what foramen do the internal carotids pass through?

A

Foramen Lacerum

74
Q

what formane do the vertebral arteries pass through?

A

foramen magnum

75
Q

label the different arteries that make up the circle of willis?

A
76
Q

what forms the circle of willis?

A

Branches of the ICA join with those of the opposite side and with the PCA (branch of the basilar artery) to form a continous circle at the base of the brain

77
Q

What branches come of the ICA?

A

Anterior communicating artery (ACA)

Middle communicating artery (MCA)

Posterior communicating artery (PComA)

78
Q

What do the anterior and middle communicating arteries supply a large part of?

A

Cerebral hemispheres

79
Q

What do the two vertebral arteries join together to form and where does this occur?

A

Basilar artery, happens on the ventral surface of the brainstem

80
Q

What does the vertebral-basilar system give off branches to supply?

A

Brainstem and cerebellum

81
Q

Where does the basiliar artery end and what does it divide into?

A

Level of the midbrain dividing into two posterior cerebral arteries (PCA) which supply the posterior part of the cerebral hemispheres

82
Q

What does ACA stand for?

A

Anterior communicating artery

83
Q

What does MCA stand for?

A

Middle communicating artery

84
Q

What does PComA stand for?

A

Posterior communicating artery

85
Q

What does PCA stand for?

A

Posterior cerebral arteries

86
Q

What does the anterior cerebral artery supply?

A

Medial aspect of cerebral hemispheres exclding occipital lobe

87
Q

What does the medial cerebral artery supply?

A
88
Q

What does the posterior cerebral artery supply?

A
89
Q

What do superficial and deep veins of the brain drain into?

A

Venous sinuses that lie between 2 layers of dura mater

90
Q

Where do venous sinuses lie between?

A

2 layers of dura mater

91
Q

Where do the dural venous sinuses drain into?

A

Join together to ultimately drain into the internal jugular veins

92
Q

label the features of this cadaveric image?

A
93
Q

label the different parts of the cavernous sinus?

A