A1 - protection of the CNS 1 Flashcards
1
Q
what 3 things is the brain composed of?
A
- cerebrum
- cerebellum
- brainstem
2
Q
what does the brainstem consist of?
A
pons, medulla and midbrain
3
Q
what are the hemispheres of the cerebrum separated by?
A
falx cerebri of the dura mater
4
Q
what bones does the cerebrum extend from anteriorly and to posteriorly?
A
frontal bone anteriorly to the occipital bone posteriorly
5
Q
what are the 4 lobes of the cerebrum and what are their main functions?
A
- frontal — motor
- parietal — sensory
- temporal — hearing
- occipital — vision
6
Q
what is a sulci?
A
groove or depression
7
Q
what is a gyrus?
A
ridge or elevation
8
Q
name 3 roles of the cerebellum
A
movement, balance, posture
9
Q
what fossae does the cerebrum full within the skull?
A
anterior and middle cranial fossae
10
Q
what layer is the cerebrum located above inferoposteriorly?
A
tentorium cerebelli
11
Q
name the fissure in the occipital lobe
A
calcarine fissure
12
Q
name A-I
A
A = occipital lobe
B = temporal lobe
C = frontal lobe
D = parietal lobe
E = central sulcus
F = lateral sulcus
G = precentral gyrus
H = postcentral gyrus
I = superior temporal gyrus
13
Q
A vs B
A
A = commissural fibres — connect RHS to LHS of brain
B = projection fibres — connect the cortex with subcortical regions and spinal cord
14
Q
what do association fibres do?
A
connect areas within the same hemisphere
15
Q
identify the different regions of the brain A-G
A
A = midbrain
B = cerebellum
C = pons
D = medulla
E = thalamus
F = hypothalamus
G = pituitary stalk
16
Q
what is the diencephalon?
A
thalamus + hypothalamus
17
Q
what is the mencephalon?
A
midbrain
18
Q
what does the hindbrain consist of?
A
pons, medulla and cerebellum
19
Q
what is another word for the brain?
A
encephalon
20
Q
where is the primary motor cortex?
A
precentral gyrus
21
Q
where is the primary sensory cortex?
A
postcentral gyrus
22
Q
what is the thalamus either side of?
A
the 3rd ventricle
23
Q
where is the motor speech area (Broca’s)?
A
in frontal lobe above lateral fissure
24
Q
where is the auditory association area (Wernicke’s)?
A
near back of temporal lobe
25
damage to Broca’s vs damage to Wernicke’s
broca’s — words dont come out
wernicke’s — words spoken perfectly but don’t make sense
26
what does the central sulcus do?
divides frontal from parietal lobe
27
what does the lateral sulcus do?
divides temporal from frontal and parietal
28
name 3 parts of basal ganglia
putamen, caudate nucleus and globus pallidus
29
what kind of fibres are in ventral rami?
sensory and motor
30
what is a dorsal root ganglion?
cell bodies of sensory neurones
31
what are the cerebral meninges?
the membranous coverings of the brain and spinal cord
32
name the 3 layers of the meninges
1. dura mater
2. arachnoid mater
3. pia mater
33
where is the CSF?
subarachnoid space
34
identify A-E
A = meningeal layer of dura mater
B = arachnoid mater
C = pia mater
D = subarachnoid space
E = arachnoid granulations
35
what are arachnoid granulations a site of?
a site of transfer of CSF into the dural venous sinuses
36
pia mater vs arachnoid mater in terms of brains concavities and convexities
pia follows all of brains concavities and convexities, arachnoid doesn’t
37
describe the dura mater
- outermost layer
- dense irregular connective tissue
- located directly underneath the bones of the skull and vertebral column
- thick, tough and inextensible
38
what are the 2 layers of dura mater?
- periosteal layer — lines the under surface of bones in cranium
- meningeal layer — located deep to the periosteal layer
39
what is between the 2 layers of the dura mater?
dural venous sinuses
40
what are dural venous sinuses responsible for? where do they empty?
responsible for venous drainage of the cranium and empt into the internal jugular vein
41
dura mater vascular supply
- receives its own vascular supply
- mainly from the middle meningeal artery and vein
42
what is the dura mater innervated by?
trigeminal nerve
43
name 3 major divisions of the brain
1. forebrain — cerebrum, thalamus, hypothalamus
2. midbrain
3. hindbrain — pons, medulla, cerebellum
44
when does an extradural haematoma occur?
when a blood-filled space occurs between the dura mater and the skull
45
what forms 4 dural reflections?
meningeal layer of dura mater
46
name the 4 dural reflections
- falx cerebri
- falx cerebelli
- tentorium cerebelli
- diaphragm sella
47
what is the largest dural reflection?
falx cerebri
48
name 2 functions of dural reflections
1. compartmentalise the cranial cavity
2. hold the brian in place and stop it rotating
49
describe the falx cerebelli
- separates the right and left cerebellar hemispheres
- projects from the midline of the occipital bone
50
describe the falx cerebri
- separates the right and left cerebral hemispheres
- blends with the tentorium cerebelli posteriorly
51
describe the diaphragma sellae
- a flat membrane — covers the pituitary stalk
- covers the hypophysial fossa of the sphenoid bone
- it contains a small opening for passage of the stalk of the pituitary gland
52
describe tentorium cerebelli
- separates the cerebrum from the cerebellum
- it is between the cerebellum and occipital lobes
- encircles the midbrain
- contains the tentorial notch = a space anteromedially for the passage of the midbrain
- spans the transverse plane from the inner surface of the occipital bone
53
which dural reflection houses the superior and inferior sagittal sinuses?
falx cerebri
54
which dural reflection houses the anterior and posterior intercavernous sinuses?
diaphragma sellae
55
which dural reflection houses the occipital sinus?
falx cerebelli
56
where are the lateral ventricles?
- within each cerebral hemisphere
- c-shaped structures
57
where is the 4th ventricle?
between the brainstem and cerebellum
58
via what do the lateral and 3rd ventricles communicate?
interventricular foramen
59
via what do the 3rd and 4th ventricles communicate? what does it extend through?
cerebral aqueduct — extends through midbrain
60
what is CSF produced by?
ependymal cells of the choroid plexus
61
what are ventricles lined with?
ependymal cells
62
identity A-F
A = lateral ventricle
B = cerebral aqueduct
C = 4th ventricle
D = interpeduncular cistern
E = quadgeminal (superior) cistern
F = cisterna manga (cerebellomedullary cistern)
63
what cistern is at the base of the brain?
interpeduncular cistern
64
what is the pontomedullary cistern?
subarachnoid cistern on the ventral aspect of the pons
65
where is the cerebellomedullary cistern?
lies between the cerebellum and the dorsal surface of the medulla
66
where does CSF flow into from the 4th ventricle?
cerebellomedullary cistern
67
identify A-E
A = superior sagittal
B = inferior sagittal
C = straight
D = confluence of sinuses
E = transverse
68
where does the transverse dural sinus drain?
drains into sigmoid —> internal jugular vein
69
what fossa is the cavernous sinus in?
middle cranial fossa
70
label the diagram
71
what do the dural venous sinuses not have?
valves
72
what is a continuation of the great cerebral vein and he inferior sagittal sinus?
straight sinus
73
what sinuses are found in the falx cerebri of the dura mater and converge at the confluence of sinuses?
straight, superior and inferior sagittal sinuses
74
label A-F
A = anterior cerebral
B = middle cerebral
C = posterior cerebral
D = internal carotid
E = vertebral
F = basilar
75
what does the vertebral artery arise from?
subclavian artery
76
draw the circle of willis
77
what does the anterior communicating unite?
the right and left anterior cerebral arteries
78
what does the posterior communicating unite?
internal carotid with the posterior cerebral arteries
79
what are A, B and C supplied by?
A = middle cerebral artery
B = posterior cerebral artery
C = anterior cerebral artery
80
what would the effects be of a lesion in the middle cerebral artery?
can have extensive detrimental effects — motor and sensory loss in upper limbs and face, speech and hearing problems
81
what the effects be of a lesion in the posterior cerebral artery?
may affect vision
82
what would the effects be of a lesion in the anterior cerebral artery?
may lead to motor and sensory loss of lower limb
83
what are the 2 lines pointing to?
superior petrosal and inferior petrosal sinuses
84
where is CSF and what is it produced by?
- produced by the choroid plexus within the cerebral ventricles
- in subarachnoid space
85
what is the choroid plexus formed from?
formed by an invagination of the vascular pia mater into the ventricular lumen, where it becomes highly convoluted — sponge-like appearance
86
how does CSF enter the ventricles?
enters 3rd and 4th through their roofs but enters the lateral ventricle through the choroid fissure
87
what is the approx volume of CSF in the combined ventricular and subarachnoid spaces?
150ml
88
how is CSF reabsorbed into the venous system?
- by passing into the dural venous sinuses, mainly the superior sagittal sinus
- absorbed through arachnoid granulations
89
describe the circulation of CSF
1. lateral ventricle
2. interventricular foramen
3. 3rd ventricle
4. cerebral aqueduct
5. 4th ventricle
6. median aperture (of Magendie) and 2 lateral apertures (of Luschka)
7. cisterna manga and cerebellopontine cisterns, respectively
8. subarachnoid space of brain and spinal cord
9. eventually reabsorbed into dural venous sinuses
90
where is most of the CSF absorbed and why?
superior sagittal and transverse sinuses — have the highest number of arachnoid granulations
91
describe the functions of the CSF
1. shock absorber, by providing a fluid buffer and thus protecting the brain from injury
2. provides neutral buoyancy — prevents the brain from compressing the blood vessels and cranial nerves against the internal surface of the bones of the skull
3. removes by-products of metabolism and plays an important role in the homeostasis and metabolism of the CNS
92
describe hydrocephalus
obstruction of flow of the CSF within the ventricular system or the subarachnoid space leading to a rise in fluid pressure causing swelling of the ventricles
93
what is the blood brain barrier?
- formed by layers of choroid plexus
- a selectively permeable barrier
94
what does the blood brain barrier consist of from superficial to deep?
- choroid ependymal cells and their tight junctions
- pia mater
- endothelial cells of capillaries
- basal membrane of endothelial capillary cells
95
what is the function of BBB?
to control the movement of water and solutes into the CSF, as well as CSF into the neural tissue
96
what dural reflection encircles the midbrain?
tentorium cerebelli
97
what does the diaphragma sella cover?
covers the hypophysial fossa of the sphenoid bone
98
the middle meningeal artery enters the middle cranial fossa via what? what does it divide into in the skull?
- foramen spinosum
- frontal and parietal branches
99
Inside the cranium the middle meningeal arteries lies between the meningeal dura mater and the _________
periosteal dura mater
100
The ________ branch of the middle meningeal artery is at risk following trauma to the lateral side of the head because it crosses the thinnest past of the skull where the frontal, parietal, sphenoid and temporal bones meet. The area is named the _________
- frontal branch
- pterion
101
The middle meningeal artery arises in the __________ fossa, which vessel does it arise from?
- infratemporal fossa
- arises from maxillary artery
102
The middle meningeal veins accompany the arteries. They exit the skull via the foramen spinosum and drain into the ________
pterygoid plexus
103
104
label the cisterns
105
106
label this cavernous sinus
107
The cavernous sinus is in direct communication with the superior and inferior ____________ and with the ___________. This has important clinical implications
superior and inferior ophthalmic veins and with the pterygoid plexus
108
the superior ophthalmic vein forms an anastomosis with the ______ vein. Therefore, the ophthalmic veins represent a potential route by which infection can spread from an __________ to an __________ site
facial vein
extracranial to intracranial site
109
Through which foramen does the internal carotid artery enter the skull?
carotid canal
110
The great cerebral vein (of Galen) unites with the inferior sagittal sinus to form which sinus?
straight sinus
111
Which sinus does the superior cerebral vein drain into?
superior sagittal
