Transcript Blood supply to the brain The cerebrospinal fluid (CSF)

Blood supply to the brain
The cerebrospinal fluid (CSF)
Mark Kozsurek, M.D., Ph.D.
[email protected]
19/09/2011, EM II.
Extremly high demand for oxygen and nutrients: human
brain represents 2% of the body weight, but receives
15% of the cardiac output, 20% of total body oxygen
consumption and 25% of total body glucose utilization.
Cerebrovascular deseases and stroke are among the
major causes of death.
Arteries supplying the brain
2 sources of blood:
ICA and VA
Vertebro-basilar system
atlas
laterally
axis
upward
backward
C6
CTA: CT angiography
C6
C7 C5
C4
cavernous
sinus
(C3)
C2
C7
C6
C5
cavernous sinus
carotid
canal
C4
C3
ant. clinoid proc.
C2
C1
foramen lacerum
X-ray angiogram
ant. cerebral
ant. communicating
middle cerebral
striate
post. communicating
ophthalmic
ant. choroidal
inf. hypophyseal
sup. hypophyseal
caroticotympanic
Circle of Willis
Circle of Willis
Circle of Willis
pituitary
stalk
optic chiasm
oculomotor n.
mamillary
bodies
abducens n.
1. Circle of Willis encloses the optic chiasm, pituitary stalk and
mamillary bodies.
2. Oculomotor nerve exits between the post. cerebral and sup.
cerebellar arteries.
3. Vertebral arteries of the two sides unite to form the basilar
artery at the ponto-medullary junction. The root of the
abducens nerve and initial segment of the ant. inf.
cerebellar artery can also be found here.
A2
A1
pericallosal br.
A3
A2
A1
ant. communicating
recurrent artery of Heubner
Heubner’s
pericallosal br.
A3
A2
A1
ant. communicating
recurrent artery of Heubner
M3
M2
M3
M2
M3
M3
ACA
PCA
MCA
PCA
anterior cerebral
middle cerebral
posterior cerebral
oculomotor n.
PCA
sca
BA
aica
VA
sca: superior cerebellar
pica
aica: anterior inferior cerebellar
pica: posterior inferior cerebellar
Veins drainig the brain
SUPERFICIAL
VEINS
superior cerebral veins
superficial middle
cerebral vein
inferior cerebral veins
Similarly, there are superior and inferior celebellar veins for the cerebellum.
Superior cerebral veins open into the superior
sagittal sinus or into the adjacent lateral lacunae.
1.
2.
3.
4.
Inferior cerebral veins
drain mainly into the
sphenoparietal (1),
cavernous (2), superior
petrous (3), and
transverse (4) sinuses.
superior sagittal sinus
TROLARD’S
VEIN
LABBE’S
VEIN
cavernous sinus
transverse sinus
DEEP
VEINS
ant. cerebral
deep middle
cerebral
basal
(Rosenthal)
great cerebral
(Galen)
of septum pellucidum
thalamostriate
int. cerebral
*
choroid
great cerebral
v. of septum pell.
great cerebral vein
Almost the total volume of veinous blood collected from
the brain leaves the skull through the jugular foramen
and the internal jugular vein.
If the jugular foramen and/or the internal jugular vein is
getting occluded, blodd may escape through the diploic
and emissary veins connecting the dural sinuses with the
veins of the scalp skin.
Diploic veins (frontal, anterior and posterior temporal, occipital):
form a network between the external and internal compact bony
layers of the skull and connect dural sinuses with the external veins.
emissary
diploic
Emissary veins (occipital, parietal, condylar, mastoid): pearce the
skull directly and connect dural sinuses with external veins.
Blood-brain barrier (BBB)
The extracellular fluid of the CNS is separated from the blood by the
BBB ensuring strictly controlled and mainly carrier protein assisted
transport of macromolecules.
Is formed by endothelial cells attached to one other by tight junctions,
basement membrane, astrocytic endfeet.
Protects the CNS from possibly toxic agents but makes development
of medicines acting on the CNS difficult (e.g. antibiotics in infections).
Life outside the BBB:
the circumventricular organs
„Circumventricular” = around the ventricles
Incomplet or missing BBB
Highly capillarized structure
Secretion of neurohormons or detection of
hormons, glucose, ions, etc.
Subfornical organ
sensory
fluid regulation
Organum
vasculosum
sensory,
secretory
detects peptides, fluid regulation
Median eminence
secretory
regulates the anterior pituitary through the release
of neurohormones
Neurohypophysis
secretory
store and secretes the hormones oxytocin and
ADH into the blood, but does not synthesize
either hormone
Subcommissural
organ
secretory
secretes certain proteins into the cerebrospinal
fluid, its specific function is as yet unknown.
Pineal gland
secretory
stimulated by darkness to secrete melatonin and
is associated with circadian rhythms
Area postrema
sensory
the vomiting centre of the brain (can detect
noxious substances in the blood and stimulate
vomiting in order to rid the body of these toxic
chemicals)
The cerebrospinal fluid (CSF)
Provides mechanical protection for the brain and the
spinal cord.
When floating in the CSF brain weights only 50g (!)
according to the Archimedes’ principle.
internal and external
CSF spaces
internal = ventricles
external = subarachnoidal space
Surface of a choroid plexus
post. choroidal from PCA
ant. choroidal from ICA or MCA
choroidal a. of the 4th ventricle from pica
median aperture
of Magendi
cerebellomedullary
(or great) cystern
lateral aperture
of Luschka
lateral pontine
(or pontocerebellar) cystern
Site of CSF resorption: arachnoid granulations in the superior
sagittal sinus and lateral lacunae.
Thank You !!!