Lecture 3 Flashcards by Kaley Kalina

How much blood circulates to the head?

20-25% of cardiac output each stroke

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What two substances does the brain rely on?

glucose and oxygen, only uses amino acids or fatty acids if absolutely necessary

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What branch primarily supplies the anterior circulation of the brain?

internal carotid artery

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Disease of which artery would be an indicator for disease in the brain?

opthalmic artery

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Which artery supplies the lateral convexity of the brain?

middle cerebral artery

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In the anterior circulation of the brain, the upper and inferior divisions of the middle cerebral artery supply what areas of the brain?

upper - frontal and parietal lobes; inferior - temporal lobe

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Which arteries travel the length of the spinal cord?

anterior and posterior spinal arteries

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Which arteries may or may not be present to complete the circle of Willis?

anterior or posteror communicating arteries, if not present you will be more prone to stroke

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Which arteries supply irrigation to the pons?

pontine arteries

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In the posterior circulation of the brain, which arteries anastomose to form the basilar artery?

vertebral arteries (come through foramen magnum)

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The oculomotor nerve lies between which two arteries?

posterior cerebral and superior cerebellar arteries

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What are the three meningeal layers covering the brain and spinal cord?

dura, arachnoid, pia

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This sinus begins at the Crista Galli and runs to the Inion (external occipital protuberance) through the midline.

superior sagittal sinus

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This major vein drains the inside of the brain.

great vein of Galen

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This sinus runs in midline straight posteriorly to the Inion, converging with the superior sagittal sinus.

straight sinus

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This sinus runs along the falx cerebri (a dural reflection), converges with straight sinus.

inferior sagittal sinus

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These sinuses run laterally on both sides of the brain that run to the Inion.

transverse sinuses

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What is the confluence of sinuses?

where the superior sagittal sinus, straight sinus, and transverse sinuses all join at the inion

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What is the sigmoid sinus?

S-shaped curve the is continuous with internal jugular vein, here there is a change of tissue type: vein (endothelial cells line the inside of veins) and sinus system (fibroblasts)

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Which sinus sits on either side of Sella Turcica?

cavernus sinus (facial–>opthalmic vein drain into)

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The cavernus sinus provides a direct entry for infection to the brain. What structures could be affected?

oculomotor, trochlear, abducens, and V1 of trigeminal (ophthalmic) can all be directly affected

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If the cavernus sinus were infected, what might be some clinical symptoms?

wouldn’t be able to track, affected eye would be dilated, and would have decreased sensation to the forehead

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Approximately how much blood is in your brain at any given time?

750 mL….conversation starter

What four types of cells contribute to the BBB?

endothelial, pericytes, neurons, astrocytes

What is the method of transport for anything crossing the BBB?

active transport

These cells act as a physical barrier by surrounding endothelial cells in the BBB.

pericyte cells

The endothelial and pericyte cells are surrounded by what structure?

basal lamina, allow certain structures through and prevent others based on size

These cells surround and act as physical structure to hold the BBB in place (scaffolding).

astrocyte cells

Through this space, infection could spread to the brain (BBB not effective).

Virchow-Robin space (subarachnoid)

Non-Protected CNS Regions

pituitary gland, median eminence of hypothalamus, area postrema, pineal gland, choroidal endothelium

Area Postrema

controls vomiting reflex, no BBB, so any substance potentially toxic you will vomit

This creates the CSF.

choroid plexus (in lateral ventricles)

Normal Flow of CSF

lateral ventricles-->foramina of Monro-->third ventricle-->cerebral aquaduct-->fourth ventricle-->2 foramina of Luschka-->central canal of spinal cord and subarachnoid space

If CSF flows into the brain but it blocked from flowing out will result in what clinically?

hydrocephalus

Why is the potassium level in the CSF less than that of blood?

neurons will not be as excitable

What are the adaptations in CSF to make it less susceptible to bacteria?

more acidic, less glucose/protein/amino acids for energy

What is the significance of the lamina terminalis?

In development it is where the anterior neuropore of neural tube closes, If this doesn’t close during development the child will have anencephaly (no brain) because the brain will not develop

Functions of the BBB

protection from exogenous substance, conservation of endogenous neurotransmitters, modulation (and/or facilitation) of metabolite fluxes, ionic homeostasis

Factors that control solute flux.

concentration gradient, capillary permeability, capillary surface area, capillary metabolism, response to chemical mediators

How can we administer drugs to bypass the BBB?

intrathecal administration (directly into CSF compartment), carotid artery infusion, specific enzyme inhibitors, enhanced capillary permeability, structural modification of molecules, ommaya reservoir (pumps directly into CSF compartment ventricles of the brain)

The middle cerebral artery runs through which sulcus?

lateral fissure (sulcus)

The primary motor cortex is associated with which gyrus?

precentral gyrus

The primary sensory cortex is associated with which gyrus?

postcentral gyrus

Broca's area

primary speech

Wernicke's area

language comprehension area

Learn all the sulcus and gyrus nomenclature.

have fun.

Which artery supplies the basal ganglia?

manticulo strait/choroidal arteries

The superior and inferior petrosal sinuses (from the cavernus sinus) merge with the sigmoid sinus and drain into which vein?

internal jugular

What is the most important determinant of solute flux in the brain?

concentration gradient, drug delivery requires a high concentration or link to a transport molecule for diffusion through BBB

In early development, this forms the lateral, 3rd, and 4th ventricles.

choroid plexus

From these 3 forramina the CSF goes into the subarachnoid space at level of foramen magnum.

foramen of Magendie and 2 foramina of Luschka

CSF returning to the brain will enter which sinus?

superior sagittal

This sulcus separates frontal and parietal lobes from temporal lobes, and looking into the sulcus the insula is visible.

lateral sulcus

This sulcus runs parallel to central sulcus and anterior to the precentral gyrus.

precentral sulcus

This sulcus runs parallel to central sulcus and posterior to the postcentral gyrus.

postcentral sulcus

Two areas of occipital lobe.

cuneus (superior) and lingual (inferior)

What is the significance of the sulcus limitans?

landmark for motor vs. sensory, below the groove is the hypothalamus (motor area), above is the thalamus (sensory relay station)