BLOOD SUPPLY OF BLOOD SUPPLY OF BRAINBRAIN

BY: BY: DR. IBRAR AHMED HASHMIDR. IBRAR AHMED HASHMI

ARTERIAL SUPPLY OF ARTERIAL SUPPLY OF BRAINBRAIN

COMMON CAROTID ARTERYCOMMON CAROTID ARTERY• 70% blood is delivered to ICA• Carotid bifurcation is a physiological

stenosis due to inertial forces of blood flow divert main flow stream from midvessel to a path along vessel margin at flow divider

• CCA divides lateral to upper border of thyriod cartilage: C3-4 intervertebral disc.

• ECA arises anterior and medial to ICA(95%)

CAROTID VESSELSCAROTID VESSELS

ARTERIAL SUPPLY OF ARTERIAL SUPPLY OF BRAINBRAIN

EXTERNAL CAROTID EXTERNAL CAROTID ARTERYARTERY

1.1. ASCENDING PHARYNGEAL ARTERYASCENDING PHARYNGEAL ARTERY

2.2. SUPERIOR THYROID ARTERYSUPERIOR THYROID ARTERY

3.3. LINGUAL ARTERYLINGUAL ARTERY

4.4. EXTERNAL MAXILLARY=FACIAL EXTERNAL MAXILLARY=FACIAL ARTERYARTERY

5.5. OCCIPITAL ARTERYOCCIPITAL ARTERY

6.6. POSTERIOR AURICULAR ARTERYPOSTERIOR AURICULAR ARTERY

7.7. SUPERFICIAL TEMPORAL ARTERYSUPERFICIAL TEMPORAL ARTERY

8.8. INTERNAL MAXILLARY ARTERYINTERNAL MAXILLARY ARTERY

INTERNAL CAROTID INTERNAL CAROTID ARTERYARTERY

1.1. CERVICAL SEGMENTCERVICAL SEGMENT

2.2. PETROUS SEGMENTPETROUS SEGMENT

3.3. CAVERNOUS SEGMENTCAVERNOUS SEGMENT

4.4. SUPRACLINOID SEGMENTSUPRACLINOID SEGMENT

INTERNAL CAROTID INTERNAL CAROTID ARTERYARTERY

• CERVICAL SEGMENT:CERVICAL SEGMENT:– Ascends posterior and medial to ECA: enters Ascends posterior and medial to ECA: enters

carotid canal of petrous bone; carotid canal of petrous bone; – NO BRANCHESNO BRANCHES– CAROTID BULB= CAROTID SINUSCAROTID BULB= CAROTID SINUS

• Dilated proximal part of ICA with thinner media and thicker adventitia containing many receptor endings of glossopharyngeal nerve.

• Baroreceptor responsive to change in arterial BP.

• Hypersensitive carotid sinus: slight touch or neck movement initiates drop in BP and SA/AV blocks.

• PETROUS SEGMENT:PETROUS SEGMENT:– Ascends briefly in carotid canal ; bends

anteromedially in horizontal course(ant to tympanic cavity and cochlea); exits near post portion foramen lacerum;ascends to juxtasellar location and pierces dural layer of cavernous sinus.

– BRANCHES: (rarely seen on angiograms)1. CORTICOTYMPANIC A.2. PTERYGOID (VIDIAN) A.(inconstant)

• CAVERNOUS SEGMENT:CAVERNOUS SEGMENT:– Ascends to posterior clinoid process, then

turns anteriorly and superomedially through cavernous sinus: exits medial to ant clinoid process piercing dura.

– BRANCHES:1. Meningohypophysial trunk2. Anterior meningeal artery3. Cavernous rami for trigeminal ganglia,

cavernous sinus and inf. petrosal sinuses.

• SUPRACLINOID SEGMENT:SUPRACLINOID SEGMENT:– Ascends posterior + lateral b/w

oculomotor and optic nerv.– BRANCHES:

1. OPHTHALMIC A.2. SUPERIOR HYPOPHYSEAL A. (not

routinely visualized)3. PCOM4. ANTERIOR CHOROIDAL A.5. MCA6. ACA

• CAROTID SIPHON: (3CAROTID SIPHON: (3rdrd + 4 + 4thth part of ICA) part of ICA)– FLOW DIRECTION: C4---C1

a)C4 SEGMENT= Before origin of ophthalmic a.

b)C3 SEGMENT= Genu of ICA.c) C2 SEGMENT= Supraclinoid segment

after origin of ophthalmic a.d)C1 SEGMENT= Terminal segment of

ICA b/w pCom + ACA.

CAROTID SIPHONCAROTID SIPHON

ANTERIOR CEREBRAL ANTERIOR CEREBRAL ARTERYARTERY

1.1. A1 SEGMENT= HORIZONTAL A1 SEGMENT= HORIZONTAL PORTIONPORTION b/w origin and aCom. b/w origin and aCom.

• Inferior branches to optic nerve and chiasmaInferior branches to optic nerve and chiasma• Superior branches to ant hypothalamus, Superior branches to ant hypothalamus,

septum pellucidum, ant commisure, fornix, septum pellucidum, ant commisure, fornix, columns,columns, medial lenticulostriate artery to medial lenticulostriate artery to anteroinferior portion of corpus striatum.anteroinferior portion of corpus striatum.

2.2. A2 SEGMENT= INTERHEMISPHERIC A2 SEGMENT= INTERHEMISPHERIC PORTION PORTION after the origin of aCom.after the origin of aCom.

• BRANCHES:BRANCHES:1.1. Medial orbitofrontal artery.Medial orbitofrontal artery.

2.2. Frontopolar artery.Frontopolar artery.

3.3. Callosomarginal artery.Callosomarginal artery.

4.4. Pericallosal artery.Pericallosal artery.

• SUPPLY: SUPPLY: anterior 2/3 of medial cerebral surface and 1cm of superomedial brain over convexity.

MIDDLE CEREBRAL MIDDLE CEREBRAL ARTERYARTERY• LLargest branch of ICA, arises lat to optic

chiasma, passes horizontal and lateral direction to enter in sylvian fissure and divides into 2/3/4 branches

• SUPPLY:SUPPLY:– Lateral cerebrumLateral cerebrum– InsulaInsula– Anterior and Lateral temporal lobesAnterior and Lateral temporal lobes

• M1 SEGMENT:M1 SEGMENT:– Origin to MCA bifurcationOrigin to MCA bifurcation– Lateral lenticulostriate Lateral lenticulostriate

• M2 SEGMENT:M2 SEGMENT:– Insular branchesInsular branches

• M3 SEGMENT:M3 SEGMENT:– MCA branches beyond sylvian fissureMCA branches beyond sylvian fissure

BLOOD SUPPLY OF BLOOD SUPPLY OF BRAINBRAIN

INTERNAL CAROTID INTERNAL CAROTID ARTERYARTERY

INTERNAL CAROTID INTERNAL CAROTID ARTERYARTERY

INTERNAL CAROTID INTERNAL CAROTID ARTERYARTERY

VERTEBRAL ARTERYVERTEBRAL ARTERY

• 11stst branch of subclavian(95%) branch of subclavian(95%)• Left vertebral arises directly Left vertebral arises directly

from aortic arch in 5%.from aortic arch in 5%.• Left artery is dominant in 50%, in Left artery is dominant in 50%, in

25% co dominant, in 25% right is 25% co dominant, in 25% right is dominant.dominant.

VERTEBRAL ARTERYVERTEBRAL ARTERY

A.A. PREVERTEBRAL SEGMENT: PREVERTEBRAL SEGMENT: Enters transverse foramina at C6, Enters transverse foramina at C6, only muscular branches. only muscular branches.

B.B. CERVICAL SEGMENT: Anterior CERVICAL SEGMENT: Anterior meningeal artery. meningeal artery.

C.C. ATLANTIC SEGMENT:ATLANTIC SEGMENT: exits exits through transverse foramina of atlas through transverse foramina of atlas till it peierces dura to enter cranial till it peierces dura to enter cranial cavity. cavity. Branch: Post. Meningeal.Branch: Post. Meningeal.

D.D. INTRACRANIAL SEGMENT:INTRACRANIAL SEGMENT:

INTRACRANIAL SEGMENTINTRACRANIAL SEGMENT• Ascends anteriorly + laterally around Ascends anteriorly + laterally around

medulla to reach midline at medulla to reach midline at pontomedullary junction and forms basilar pontomedullary junction and forms basilar artery with other vertebral a at clivus.artery with other vertebral a at clivus.

• BRANCHES:BRANCHES:1.1. ANTERIOR + POSTERIOR SPINAL A.ANTERIOR + POSTERIOR SPINAL A.

2.2. PICAPICA BASILAR ARTERY BRANCHES:BASILAR ARTERY BRANCHES:

1.1. AICAAICA

2.2. INTERNAL AUDITORY A.INTERNAL AUDITORY A.

3.3. SUPERIOR CEREBELLAR A.SUPERIOR CEREBELLAR A.

4.4. POSTERIOR CEREBRAL A.POSTERIOR CEREBRAL A.

5.5. MEDULLARY AND PONTINE MEDULLARY AND PONTINE PERFORATING ARTERIESPERFORATING ARTERIES

POSTERIOR CEREBRAL ARTERYPOSTERIOR CEREBRAL ARTERY• Originates from bifurcation of basilar

artery, within interpeduncular cistern (in 15% as direct continuation of pCom) lies above occulomotor nerve and circles midbrain above tentorium.

• P1 SEGMENT:P1 SEGMENT:– Origin to PCOM.Origin to PCOM.– Posterior thalamoperforatorsPosterior thalamoperforators

• P2 SEGMENT:P2 SEGMENT:– Distal to PCOMDistal to PCOM– ThalamogeniculateThalamogeniculate– Posterior choroidal arteries.Posterior choroidal arteries.

• TERMINAL CORTICAL BRANCHES.TERMINAL CORTICAL BRANCHES.

ARTERIAL ANASTOMOSES ARTERIAL ANASTOMOSES OF BRAINOF BRAIN

A.A. AT BASE OF BRAIN:AT BASE OF BRAIN:I.I. CIRCLE OF WILLISCIRCLE OF WILLIS

II.II. DEVELOPMENTAL ANOMALIES: DEVELOPMENTAL ANOMALIES: (3 transient carotid-basilar (3 transient carotid-basilar anastomoses appear in fetal life)anastomoses appear in fetal life)

• Primitive hypoglossal arteryPrimitive hypoglossal artery• Primitive acoustic arteryPrimitive acoustic artery• Persistent primitive trigeminal arteryPersistent primitive trigeminal artery

CIRCLE OF WILLISCIRCLE OF WILLIS

• Complete in 25%, Complete in 25%, incomplete in 75%.incomplete in 75%.

• Made byMade by– Supraclinoid ICAsSupraclinoid ICAs– A1 segment of A1 segment of

ACAACA– ACOMsACOMs– PCOMsPCOMs– P1 segment of P1 segment of

PCAsPCAs

ARTERIAL ANASTOMOSES ARTERIAL ANASTOMOSES OF BRAINOF BRAIN

B.B. VIA SURFACE VESSELS:VIA SURFACE VESSELS:• LEPTOMENINGEAL ANASTOMOSES LEPTOMENINGEAL ANASTOMOSES

OF CEREBRUM: OF CEREBRUM: ACA ACA MCA MCA PCA PCA

• OF CEREBELLUM: OF CEREBELLUM: SUP CEREBELLAR SUP CEREBELLAR AICA AICA PICA. PICA.

C.C. RETE MIRABILE:RETE MIRABILE:• ECAECA MIDDLE MENINGEAL/SUP MIDDLE MENINGEAL/SUP

TEMPORAL A. TEMPORAL A. LEPTOMENINGEALLEPTOMENINGEAL ACA/MCA. ACA/MCA.

NORMAL VARIANTS OF NORMAL VARIANTS OF VASCULAR ANATOMYVASCULAR ANATOMY

• ICA:ICA:– PERSISTENT EMBRYONIC ARTERIESPERSISTENT EMBRYONIC ARTERIES– ABERRANT PETROUS PART ICA: Courses ABERRANT PETROUS PART ICA: Courses

posterolateral posterolateral

• ECA:ECA:– MIDDLE MENINGEAL FROM OPHTHALMICMIDDLE MENINGEAL FROM OPHTHALMIC– VARIATION IN ORDER OF BRANCHING.VARIATION IN ORDER OF BRANCHING.

• CIRCLE OF WILLIS:CIRCLE OF WILLIS:– HYPOPLASTIC PCOMHYPOPLASTIC PCOM– HYPOPLASTIC OR ABSENT A1 SEGMENTHYPOPLASTIC OR ABSENT A1 SEGMENT– FETAL PCA(FROM ICA) WITH ATRETIC P1 FETAL PCA(FROM ICA) WITH ATRETIC P1

SEGMENTSEGMENT– HYPOPLASTIC ACOM.HYPOPLASTIC ACOM.

ANTERIOR CEREBRAL ANTERIOR CEREBRAL ARTERYARTERY

MIDDLE CEREBRAL MIDDLE CEREBRAL ARTERYARTERY

POSTERIOR CEREBRAL ARTERYPOSTERIOR CEREBRAL ARTERY

CEREBRAL VEINSCEREBRAL VEINS

THANK YOUTHANK YOU