2. INTRODUCTION
About 18% of the total blood volume in the body
circulates in the brain, which accounts for about 2%
of the body weight.
loss of consciousness occurs in less than 15
seconds after blood flow to the brain has
stopped, and irreparable damage to the brain tissue
occurs in about 5 minutes.
Blood supply = arterial supply + venous drainage
7. CIRCLE OF WILLIS
The circle of Willis (after the
English neuroanatomist Sir Thomas
Willis
Formed by
Vertebro-basilar system branches
Internal carotid and its branches
11. PICA
the largest branch of the vertebral artery arises at the caudal end of
the medulla on each side
Runs a course winding between the medulla and cerebellum
It supplies
a. posterior part of cerebellar hemisphere
b. inferior vermis
c. central nuclei of cerebellum
d. choroid plexus of 4th ventricle
e. medullary branches to dorsolateral medulla
12.
13. AICA
It arises from the basilar artery at the level of the junction
between the medulla oblongata and the pons in the brainstem.
It passes backward to be distributed to the anterior part of the
undersurface of the cerebellum, anastomosing with the
posterior inferior cerebellar branch of the vertebral artery.
It supplies
a. the anterior inferior quarter of the cerebellum.
b. the middle cerebellar peduncle,
c. facial (CN VII) and vestibulocochlear nerves (CN VIII)
14. SUPERIOR CEREBELLAR
ARTERY
Branch of from lateral aspect of basilar artery
It supplies
a. most of the cerebellar cortex,
b. the cerebellar nuclei, and
c.
The superior cerebellar peduncles
19. POSTERIOR CEREBRAL
ARTERY
1. Central branches
Thalamoperforating &
thalamogeniculate
supply the medial surfaces of the
thalami and the walls of the third
ventricle
Peduncular perforating branches
supply a considerable portion of
the thalamus.
20. POSTERIOR CEREBRAL
ARTERY
2. Choroidal branches
Medial posterior choroidal
branches
supply the tela chorioidea of the
third ventricle and the choroid
plexus
Lateral posterior choroidal
branches
small branches to the cerebral
peduncle, fornix, thalamus, and
the caudate nucleus
21. POSTERIOR CEREBRAL
ARTERY
3. Cortical branches
Anterior temporal & Posterior temporal
Lateral occipital
Medial occipital
Splenial or the posterior pericallosal branch
Supplies infero-medial part of the temporal
lobe,
occipital pole, visual cortex, and
splenium of the corpus callosum
23. MIDDLE CEREBRAL
ARTERY
arises from the Internal Carotid
continues to lateral sulcus and divides into different branches
Course is divided into segments M1, M2 , M3 , M4
M1 from orgin to trifurcation
M2 from bifurcation to origin of cortical branches
M3 opercular branches (within sylvian fissure)
M4 emerges from sylvian fissure into surface of the hemisphere
26. MCA (BRANCHES)
M2
Superior and inferior and some times to middle branch
Superior terminal branch
•lateral frontobasal (orbito-frontal) artery
•prefrontal sulcal artery
•pre-Rolandic (precentral) and Rolandic (central) sulcal arteries
Inferior terminal branch
•three temporal branches (anterior, middle, posterior)
•branch to the angular gyrus
•two parietal branches (anterior, posterior)
30. ANTERIOR CEREBRAL
ARTERY
forms at the termination of the
internal carotid artery
arches antro-medially to pass
anterior to genu of the corpus
callosum
It supplies medial aspect of the
cerebral hemispheres back to the
parietal lobe.
segments
•A1 - origin from the ICA to the
anterior communicating artery
(ACOM)
•A2 - from ACOM to the origin of the
callosomarginal artery
35. INTERNAL CAPSULE
BLOOD SUPPLY
INTERNAL CAROTID Ant.
Choroidal artery
Supply lower part of posterior limb &
retro-lentiform part
inferolateral part of the lateral
geniculate body.
ACA Medial striate branch
(Heubner’s)
the lower part of the anterior limb and
genu of the internal capsule
MCA Lateral striate (lenticulostriate)
Supplies to the anterior
limb, genu, and posterior limb of the
internal capsule
36. WATERSHED ZONES
Area where the
blood supply of
cortical vessels
overlap. These
overlapping
vessels are
Terminal
branches
Watershed
Infarct:
An area of
necrosis in the
brain caused by
an insufficiency of
blood where the
distributions of
60. Structure:
The walls of the dural venous sinuses are composed of dura
mater lined with endothelium
Name
Inferior sagittal
sinus
Superior sagittal
sinus
Drains to
Straight sinus
Typically becomes right transverse sinus or
confluence of sinuses
Straight sinus
Typically becomes left transverse sinus or
confluence of sinuses
Occipital sinus
Confluence of sinuses
Confluence of
sinuses
Sphenoparietal
sinuses
Right and Left transverse sinuses
Cavernous sinuses
Cavernous sinuses
Superior and inferior petrosal sinuses
Superior petrosal
sinus
Transverse sinuses
61.
62. CAVERNOUS SINUS
Lateral to body of sphenoid bone
Lateral to body of sphenoid bone
Connected to opposite – intercavernous S
Receives blood
Middle cerebral V
Drains into
Int Jugular V –via Inf petrosal sinus
Transverse S – via Sup petrosal S
Dural Venous sinuses – emissary veins – extracranial V
At the upper margin of the Axis (C2) it moves outward and upward to the transverse foramen of the Atlas (C1). It then moves backwards along the articular process of atlas into a deep groove, passes beneath the atlanto-occipital ligament and enters the foramen magnum. The arteries then run forward and unite at the caudal border of the pons to form the basilar artery
Direct branch of the vertebral arteries . As is Anterior Spinal Artery
Inferior to bifurcation of PCA The SCA branches off the lateral portion of the basilar artery, just inferior to its bifurcation into the posterior cerebral artery. Here, it wraps posteriorly around the pons (to which it also supplies blood) before reaching the cerebellum. The SCA supplies blood to most of the cerebellar cortex, the cerebellar nuclei, and thesuperior cerebellar peduncles
Just an introduction on the vascular territory of brain and water shed zones……
P1 peduncal arises near the intersection of the posterior communicating artery and basilar arteryBranches
BRANCHES --- CENTRAL + CHOROIDAL + CORTICALa group of small arteries which arise at the commencement of the posterior cerebral artery: these, with similar branches from the posterior communicating, pierce the posterior perforated substance, and supply the medial surfaces of the thalami and the walls of the third ventricle.The thalamogeniculateartery shown supplies thegeniculate bodies and theposterior two-thirds of thethalamus.Peduncular perforating or postero-lateral ganglionic branches: small arteries which arise from the posterior cerebral artery after it has turned around the cerebral peduncle
Anterior temporal, distributed to the uncus and the anterior part of the fusiform gyrusPosterior temporal, to the fusiform and the inferior temporal gyriMedial occipital, which branches into the:Calcarine, to the cuneus and gyruslingualis and the back part of the convex surface of the occipital lobeParieto-occipital, to the cuneus and the precuneus
As mentioned earlier IC and its branches form the anterior Circulation will discuss on details
The middle cerebral arteries supply the majority of the lateral surface of the hemisphere apart from the superior portion of the parietal lobe and the inferior portion of the temporal lobe and occipital lobe. In addition, they supply part of the internal capsule and basal ganglia.
Division of the MCA is variable after the horizontal segment, although most commonly, it divides into two trunks - superior and inferior :78% bifurcate into superior and inferior divisions 12% trifucate into superior, middle and inferior divisions 10% branch into many smaller branchescharcoats Supply the Corpus striatum, internal capsule, and Anterior ofthalamus.
# 50% in A2 44% in A1 6% from A Co A It supplies head of caudate and adjacent part of the internal capsuleCortical branches supply anterior 2/3rds of medial hemisphere . Small superior area extending over convexities
pericallosal artery *with the exception of the spleniumParacentral lobule – responsible for lower limb
Territory supplied by branches of the anterior and middle cerebral arteries is shown in red. Territorysupplied by the anterior choroidal artery is shown in green.
There are two patterns of border zone infarcts:1.Cortical border zone infarctions Infarctions of the cortex and adjacent subcortical white matter located at the border zone of ACA/MCA and MCA/PCA 2.Internal border zone infarctions Infarctions of the deep white matter of the centrum semiovale and corona radiata at the border zone between lenticulostriate perforators and the deep penetrating cortical branches of the MCA or at the border zone of deep white matter branches of the MCA and the ACA.
Just to summariz
Superior Sagittal SinusInfreior Sagittal Sinus Transverse sinus , sigmoid sinus Cavernous sinusws, superior and inferior petrosal sinusesFigure shows relationshi[