Meninges, Ventricles

Front 1

What are the layers of the dura mater?

Back 1

an external, endosteal, and an internal,
meningeal, layer. These two layers are grossly indistinguishable; however, their
bilaminar nature is apparent in those regions where they are separated by the large
cerebral venous sinuses

Front 2

serves as the periosteum of the inner table of
the skull and is rich both in blood vessels and nerves

Back 2

external/endosteal layer of dura

Front 3

The falx cerebri, falx cerebelli, tentorium cerebelli, and diaphragma sella are portions of what?

Back 3

internal/meningeal layer of dura

Front 4

Innervation of dura

Back 4

a. The supratentorial portion - sensory innervation is provided by branches of the
trigeminal nerve.

b. The infratentorial portion - sensory innervation is provided by the meningeal
branches of the vagus and by the meningeal branches of the first three cervical
nerves.

Front 5

Does the spinal dura also have 2 layers?

Back 5

The spinal dura
consists only of this one layer as the vertebrae have their own separate
periosteum.

Front 6

What is the leptomeninges?

Back 6

Arachnoid membrane and pia mater

Front 7

What are the arachnoid granulations?

Back 7

The cerebral arachnoid sends tufted prolongations, called the arachnoid
granulations, through the inner layer of the dura into the superior sagittal sinus. It
is through these granulations that the cerebrospinal fluid passes into the venous
blood.

Front 8

Layers of spinal pia

Back 8

inner intimal layer
(membranous) and an outer epipial layer (loose collagen fibers). Around the brain
the epipial layer is poorly developed, consequently superficial arteries and veins
of the cortex lie on the intimal pia in the subarachnoid space.

Front 9

What is the clinical relevance of the fact the epipial layer is poorly developed in in brain?

Back 9

superficial arteries and veins
of the cortex lie on the intimal pia in the subarachnoid space. This is of clinical
importance as these vessels are exposed to the CSF and thus, alterations therein
can elicit vascular change. The presence of blood in CSF due to aneurysmal
bleeding or other causes can trigger reactive vascular change leading to
vasospasm. This decreases cerebral blood flow with serious CNS consequences.
In the spinal cord, the blood vessels run within the epipial tissue.

Front 10

Which meningeal layer dips into the sulci of brain?

Back 10

pia

Front 11

midline third ventricle communicates with the midline fourth ventricle via

Back 11

Sylvian aqueduct

Front 12

Fourth ventricle communicates with the subarachnoid space via

Back 12

foramina of Magendie and Luschka.

Front 13

Communication between the two lateral
ventricles and the third ventricle is established through

Back 13

The paired foramina of Monroe

Front 14

Lateral ventricles:
The anterior horn is roofed by the _______. Its medial wall is formed by
the __________, while the floor and lateral wall are formed by the _____________.

Back 14

corpus callosum; septum pellucidum; head of
the caudate nucleus

Front 15

a thin space in the midline of the diencephalon, bounded by
the thalami and hypothalami.

Back 15

3rd ventricle

Front 16

midline cavity whose floor is formed by the substance of
the medulla and the pons and whose roof is formed by the cerebellum.

Back 16

4th ventricle

Front 17

Where are the choroid plexuses found?

Back 17

within all the ventricles

Front 18

How does CSF drain?

Back 18

Drains thru the ventricles (lateral->3rd->4th) then thru paired lateral foramina of Luschka.to reach the subarachnoid space approximating the brain stem. From here, the fluid
travels upward in the subarachnoid space over the cortical convexities to reach the
arachnoid granulations which protrude directly into the superior sagittal sinus or its
related lacunae. In general, the CSF is under a 5-10 mm/Hg pressure, while the sinus
pressure approximates 0. This pressure difference creates transcellular channels in
arachnoid villi and allows the CSF to move into the venous return.

Front 19

What would happen if venous pressure rises?

Back 19

CSF drainage would be impaired. CSF drainage depends on the higher pressure of the CSF to drain into the venous sinuses.

Front 20

What does CSF have WAY less of than blood?

Back 20

Amino acids, proteins, Igs

Front 21

Subarachnoid hemorrhage from
ruptured aneurysm would include what in the CSF LP that's not normally there?

Back 21

RBCs

Front 22

What would bacterial/fungal meningitis show in the CSF LP?

Back 22

WBCs and lowered glucose

Front 23

Elevated gamma globulins most likely IgG - discrete
subfractions forming oligoclonal bands in the CSF would be a sign of what?

Back 23

MS

Front 24

T/F choroid epithelial cells are sealed by tight junctions

Back 24

T

Front 25

vascular supply of cerebral dura is mainly from _______

Back 25

middle meningeal artery

Front 26

purpose of Na/K pump sitting on surface facing CSF

Back 26

Pumps Na in, pulls K out
(of CSF)

Front 27

T/F Brain become hypermetabolic – metabolism of brain can possibly outstrip blood flow.

Back 27

T

Front 28

2 major artery systems in the brain

Back 28

Vertebral-basilar system and carotid system

Front 29

What links the 2 systems?

Back 29

posterior communicating artery

Front 30

CN III is always found between what 2 arteries?

Back 30

Posterior cerebral and superior cerebellar

Front 31

Which vessel of the circle of Willis is mostly likely to be hypoplastic/nonfunctioning?

Back 31

Typically, the posterior
communicating shows the most predilection for hypoplasia

Front 32

What arteries does the internal carotid a. give off after it goes thru the cavernous sinuses?

Back 32

1) Ophthalmic
2) Posterior communicating
3) Anterior Choroidal
4) Anterior cerebral
5) Middle cerebral

Front 33

What arteries enter the cranial vault through the foramen magnum?

Back 33

Vertebral

Front 34

What arteries do the vertebral arteries give off?

Back 34

1) PICA
2) Anterior spinal
3) Posterior spinal

Front 35

Branches of basilar artery (from fusion of 2 vertebrals)

Back 35

1) AICA
2) Pontine arteries
3) Superior cerebellar
4) Posterior cerebral
5)Labyrinthine/auditory a

Front 36

T/F Cerebral veins parallel cerebral arteries

Back 36

F

Front 37

. Elevated PaC0 2 , lowered Pa0 2 or a
reduction in pH will cause _______. Lowered PaC0 2 or increased pH will cause
__________________.

Back 37

vasodilation; vasoconstriction

Front 38

Sympathetic input will cause ________. Limited parasympathetic
input will cause ____________.

Back 38

vasoconstriction ; vasodilation

Front 39

What causes the BBB?

Back 39

capillary endothelium

Front 40

What are unique props of brain's vascular endothelium?

Back 40

1. Unlike non-neural vascular beds, the brain's vascular endothelium lacks
fenestrations and vesicles.

2. Unlike many non-neural vascular beds, the brain's vascular endothelium is joined
by continuous tight junctions.

3. Thus, the brain's vasculature appears as a continuous endothelial layer bound
together by tight junctions. In essence then, the BBB can be viewed as a
continuous lipoprotein plasma membrane.

Front 41

What do these sites have in common:
a. Choroid plexus
b. Median eminence of the hypothalamus
c. Subfornical organ
d. Area postrema
e. Pineal gland

Back 41

No BBB. Endothelium is fenestrated here.

Front 42

cerebrovascular endothelium behaves as a____________

Back 42

continuous lipoprotein membrane

Front 43

T/F Lipid soluble non-
electrolytes would readily diffuse through such a membrane, whereas non-lipid soluble
agents would not pass readily.

Back 43

T

Front 44

T/F water diffuses thru BBB

Back 44

T

Front 45

T/F small ions diffuse thru BBB

Back 45

F

Front 46

T/F Glucose (D-glucose but not L glucose) readily crosses the BBB

Back 46

T

Front 47

T/F certain compounds are actively transported thru BBB in the blood --> brain direction

Back 47

F. There is some evidence for certain things in the other direction tho

Front 48

T/F BBB contains numerous enzymes which degrade
compounds moving through the vascular endothelium.

Back 48

T. Don't want active NTs to get into the BBB unless tightly controlled.

Front 49

Where is the blood-CSF barrier?

Back 49

choroid plexuses

Front 50

How does glucose get into brain?

Back 50

Glucose passes by facilitated diffusion through the wall of blood vessels and is
largely taken up by astrocytes.

Front 51

___________is the rate-limiting step in glycolysis during aerobic respiration

Back 51

Hexokinase

Front 52

What happens to the glucose that gets into the brain?

Back 52

85% goes thru glycolysis for aerobic respiration

5% for glycogen storage

5% to pentose shunt

Front 53

Phospho-glucose isomerase
: significance of in brain

Back 53

Enzyme that uses G6P to enter aerobic pathway/glycolysis

Front 54

What is the rate-limiting step for entering oxidative phosphorylation?

Back 54

Pyruvate dehydrogenase

Front 55

Which neurons are the most sensitive to hypoglycemia, and therefore the first to die ?

Back 55

Glutamatergic neurons

Front 56

What is astrocytes-neuron lactate
shuttle ?

Back 56

theorized to support rapid neuronal firing rates;
however, neurons will also perform glycolysis, particularly when at rest.

Glucose taken up by astrocytes, which export lactate to neurons (also reduces NADH to NAD+ to facilitate glycolysis).
Neurons convert lactate back to pyruvate to feed aerobic respiration.
Astrocytes maintain glycogen reserve – used to produce extra lactate upon heightened demand

Front 57

What's the glutamate feedback loop?

Back 57

Astrocyte processes sense level of glu that’s being released. If [glu] goes up, it calls for more glucose to be converted to lactate.

Front 58

Prenatal brain relies on what process for energy?

Back 58

glycolysis, not aerobic respiration.

Front 59

T/F At birth, lipid
production increases and the brain becomes ketotic in response to the high fat content of
mother’s milk. At this point ketones are a significant fuel source and the brain is actual
hypoglycemic

Back 59

T

Front 60

What's used for myelination?

Back 60

ketones

Front 61

Childhood brain uses ___ of oxygen consumed.

Back 61

50%

Front 62

T/F After about age 20, metabolism of brain is kept pretty constant unless there's a disease process

Back 62

T

Front 63

What happens in hyperinsulinemia?

Back 63

Despite normal oxygenation
and blood flow, inadequate glucose will stop aerobic metabolism and if severe enough
will end up in coma.

(Free FAs decreased in this case too)

Front 64

What happens to neurons when ATP runs out?

Back 64

ion pump function fails within a
few minutes (Fig. 5). Potassium exits the cell and sodium floods in. The cell membrane
depolarizes within minutes and proton and calcium ion channels open. Once flooded
with calcium, proteases will activate and induce cell death within minutes to hours.

Front 65

What is spreading depression?

Back 65

dying neurons release K+ from their insides to ECM. This depolarizes surrounding neurons and causes their deaths.

Front 66

What is excitotoxicity?

Back 66

When dying neurons release glutamate, causing activation of NMDArs and opening of Ca2+ channels.

Front 67

TPA is adminstered in cases of ______

Back 67

ischemic stroke

Front 68

Foramen of Magendia is _______ while foramen of Luschka is _________

Back 68

medial; lateral.

Both are involved in draining CSF from 4th ventricle to subarachnoid space.