Module 20: Blood Supply to the Brain, Meninges, Ventricles, and CSF

dura mater

outer layer of the meninges

dura mater

thickest layer of the meninges

dura mater

contains the venous sinuses

dura mater

forms reflections that fit into large crevasses in the brain

dura mater

has a periosteal layer and a meningeal layer

arachnoid mater

contains a filamentous mesh called trabeculae

arachnoid mater

thin, avascular, and transparent membrane

arachnoid mater

middle layer of the meninges

arachnoid mater

contains granulations that allow CSF to return to the bloodstream

pia mater

thin, innermost layer of the meninges

pia mater

supports large cerebral blood vessels on the surface of the brain

pia mater

follows the contours of the sulci and gyri

falx cerebri

located within the median longitudinal fissure

• contains superior sagittal sinus and inferior sagittal sinus

falx cerebelli

located between the right and left hemispheres of the cerebellum

tentorium cerebelli

located inferior to the occipital lobes, between the cerebrum and cerebellum

subarachnoid space

the space surrounding the brain within the meninges that contains CSF is called the:

subarachnoid space

contains blood vessels

subarachnoid space

is located between the arachnoid mater and pia mater

subarachnoid space

has arachnoid trabeculae, which are web-like threads extending across the ___

choroid plexus

CSF is produced by the ___

ependymal cells & highly-permeable capillaries

CSF production involves ___ & ___

true

True or False

CSF is constantly being produced

false

True or False

CSF is only produced within the lateral ventricle

• pressure from the constant production of CSF

• movement of the vertebral column

• movement of cilia on the ependymal cells

What helps the CSF move around the brain and spinal cord? (3)

CSF

maintains the environment around the brain

CSF

provides buoyancy for the brain

CSF

transports hormones, nutrients, chemicals, and wastes

septum pellucidum

the ___ separates the right and left lateral ventricles from each other

blood-brain barrier (BBB)

endothelial transport across the ___ is highly selective

blood-brain barrier (BBB)

the endothelial cells of the ___ contain small numbers of pinocytotic vesicles

blood-brain barrier (BBB)

lipid-soluble compounds can freely diffuse across the endothelial cell membranes

blood-brain barrier (BBB)

the endothelial cells of the ___ are extensively interconnected with tight junctions

1. lateral ventricles

2. intervertebral foramen (of Monro)

3. third ventricle

4. cerebral aqueduct

5. fourth ventricle

6. lateral apertures/median aperture/central canal

7. subarachnoid space

8. arachnoid granulations

9. dural venous sinuses

flow of CSF (9)

cranial meninges

cover and protect the brain

• protect against foreign substances, trauma, etc.

• separate the soft tissue of the brain from the bones of the cranium

cranial meninges

enclose and protect blood vessels

• support vessels supplying the brain

• form some of the veins (venous sinuses) draining blood from the brain

cranial meninges

stabilize the brain within the skull

cranial meninges

contain the CSF

meninges

are anchored to the skull, and the brain is suspended within the ___

meninges

extend around the spinal cord and are continuous throughout the CNS

periosteal layer

fused to the periosteum on the inner aspect of the skull (more superficial & lies between the dura mater and the arachnoid mater)

meningeal layer

closer to the arachnoid mater

dural venous sinuses

space between the periosteal & meningeal dura forms these large collecting veins

• veins of the brain empty into these sinuses

superior sagittal sinus

runs in the groove of the median longitudinal fissure, where it absorbs CSF from the meninges

inferior sagittal sinus

is in the inferior aspect of the falx cerebri within the median longitudinal fissure

straight sinus

connecting the inferior sagittal and superior sagittal sinuses, midline with the tentorium cerebelli

confluence of sinuses

posterior, where the superior sagittal, straight, and transverse sinuses merge

superior sagittal sinus, inferior sagittal sinus, transverse sinuses, straight sinus, confluence of sinuses

dural venous sinuses (5)

sigmoid sinus

• blood returns to jugular vein via the ___

• is a continuous of the transverse sinus

cranial dural reflections

where the meningeal layer of dura extends deep into the cranial cavity between sections of the brain

1. subdivide cranial cavity

1. support the brain

2. limit movement of the brain

cranial dural reflections (3)

epidural space

space located between the dura mater and the skull

subdural space

a potential space between the dura and the arachnoid mater, containing a thin layer of serous fluid (closer to the arachnoid)

arachnoid granulations

send CSF from the subarachnoid space into the blood within the superior sagittal sinus

subarachnoid space

between the arachnoid and pia mater

arachnoid trabeculae

the ___ are found in the subarachnoid space

arachnoid trabeculae

web like threads extending across the subarachnoid space from arachnoid mater to pia mater

subarachnoid space

contains CSF and blood vessels

choroid plexus

removes waste from CSF and alters its composition as-needed

CSF

colorless fluid that circulates in the ventricles and subarachnoid space

CSF

protection: brain floats in the ___ and does not sit against the skull

ependymal cells

• a glial cell

• surround blood capillaries in the choroid plexus and filter the blood to make CSF

lateral ventricles

• one in each hemisphere

• has an anterior horn, body, posterior horn, and inferior horn that extends into the temporal lobes

3rd ventricle

midline, between the right and left thalamus

3rd ventricle

interthalamic adhesion connecting the right and left thalamus forms the “hole” in the ___

4th ventricle

between the pons & cerebellum, extending into the superior portion of the medulla oblongata

interventricular foramen (of monro)

two of these, each connecting one lateral ventricle to the 3rd ventricle

cerebral aqueduct

connects the 3rd ventricle to the 4th ventricle

1. lateral aperture on either side of the 4th ventricle

2. median aperture at the midlin, posterior aspect of the 4th ventricle

3. central canal of the spinal cord

CSF can leave the 4th ventricle through:

blood-brain barrier (BBB)

tightly regulates what can leave the blood vessels and enter the space surrounding the brain tissue

blood-brain barrier (BBB)

continuous capillaries

blood-brain barrier (BBB)

extensive tight junctions prevent materials from diffusing between epithelial cells

blood-brain barrier (BBB)

astrocyte perivascular feet surround the capillaries

blood-brain barrier (BBB)

astrocytes restrict permeability of the capillary endothelial cells

blood-brain barrier (BBB)

increased permeability in parts of the hypothalamus allowing hormone diffusion

blood-brain barrier (BBB)

pituitary gland capillaries allowing hormone diffusion

blood-brain barrier (BBB)

high permeability in the pineal gland capillaries

blood-brain barrier (BBB)

choroid plexus capillaries for production of CSF

1. superior sagittal sinus or inferior sagittal to straight sinus

2. confluence of sinuses

3. transverse sinus

4. sigmoid sinus

5. internal jugular vein (merges with subclavian vein to form…)

6. brachiocephalic vein (right and left merge to form…)

7. superior vena cava

8. heart

veins of the head & neck (8)

internal carotid arteries

the right and left ___ branch from the common carotid artery on each side and enter the cranium through the carotid canal in the temporal bone

vertebral arteries

the ___ branch off of the subclavian arteries on each side, and they are protected as they pass through the neck region by the transverse foramina of the cervical vertebrae

basilar artery

the two vertebral arteries merge into the ___, which gives rise to branches to the brainstem and cerebellum

posterior cerebral arteries

The basilar artery then ends by dividing into the right and left ___, which supply the occipital lobe and inferior aspect of the posterior temporal lobe.

circle of willis

___ is a confluence of arteries that can maintain perfusion of the brain even if narrowing or a blockage limits flow through one part

anterior cerebral artery

supplies blood to the anterior, medial, and very superior portions of the frontal lobe

middle cerebral artery

supplies blood to the posterior frontal lobe and most of the temporal and parietal lobes

anterior communicating artery

the right and left anterior cerebral arteries join together to form an anastomosis called the ___

posterior communicating artery

the posterior portion of the arterial circle is formed by a left and a right ___ that runs from the internal carotid artery to the posterior cerebral artery on each side

middle cerebral artery

both Broca’s area and Wernicke’s area are located in areas supplied by the ___