Transcript RADIOLOGICAL BRAIN ANATOMY

BLOOD SUPPLY OF
BRAIN
BY:
DR. IBRAR AHMED HASHMI
ARTERIAL SUPPLY OF BRAIN
COMMON 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 VESSELS
ARTERIAL SUPPLY OF BRAIN
EXTERNAL CAROTID ARTERY
1.
2.
3.
4.
5.
6.
7.
8.
ASCENDING PHARYNGEAL ARTERY
SUPERIOR THYROID ARTERY
LINGUAL ARTERY
EXTERNAL MAXILLARY=FACIAL ARTERY
OCCIPITAL ARTERY
POSTERIOR AURICULAR ARTERY
SUPERFICIAL TEMPORAL ARTERY
INTERNAL MAXILLARY ARTERY
INTERNAL CAROTID ARTERY
1.
2.
3.
4.
CERVICAL SEGMENT
PETROUS SEGMENT
CAVERNOUS SEGMENT
SUPRACLINOID SEGMENT
INTERNAL CAROTID ARTERY
•
CERVICAL SEGMENT:
–
Ascends posterior and medial to ECA: enters carotid canal
of petrous bone;
–
–
NO BRANCHES
CAROTID 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:
–
–
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:
–
–
Ascends to posterior clinoid process, then turns
anteriorly and superomedially through cavernous
sinus: exits medial to ant clinoid process piercing
dura.
BRANCHES:
1. Meningohypophysial trunk
2. Anterior meningeal artery
3. Cavernous rami for trigeminal ganglia, cavernous
sinus and inf. petrosal sinuses.
•
SUPRACLINOID SEGMENT:
–
–
Ascends posterior + lateral b/w oculomotor
and optic nerv.
BRANCHES:
1. OPHTHALMIC A.
2. SUPERIOR HYPOPHYSEAL A. (not routinely
visualized)
3. PCOM
4. ANTERIOR CHOROIDAL A.
5. MCA
6. ACA
•
CAROTID SIPHON: (3rd + 4th 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 SIPHON
ANTERIOR CEREBRAL ARTERY
1. A1 SEGMENT= HORIZONTAL
PORTION b/w origin and aCom.
•
•
Inferior branches to optic nerve and chiasma
Superior branches to ant hypothalamus, septum
pellucidum, ant commisure, fornix, columns,
medial lenticulostriate artery to anteroinferior
portion of corpus striatum.
2. A2 SEGMENT= INTERHEMISPHERIC
PORTION after the origin of aCom.
•
BRANCHES:
1.
2.
3.
4.
•
Medial orbitofrontal artery.
Frontopolar artery.
Callosomarginal artery.
Pericallosal artery.
SUPPLY: anterior 2/3 of medial cerebral surface
and 1cm of superomedial brain over convexity.
MIDDLE CEREBRAL ARTERY
• Largest 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:
– Lateral cerebrum
– Insula
– Anterior and Lateral temporal lobes
• M1 SEGMENT:
– Origin to MCA bifurcation
– Lateral lenticulostriate
• M2 SEGMENT:
– Insular branches
• M3 SEGMENT:
– MCA branches beyond sylvian fissure
BLOOD SUPPLY OF BRAIN
INTERNAL CAROTID ARTERY
INTERNAL CAROTID ARTERY
INTERNAL CAROTID ARTERY
VERTEBRAL ARTERY
• 1st branch of subclavian(95%)
• Left vertebral arises directly from aortic arch
in 5%.
• Left artery is dominant in 50%, in 25% co
dominant, in 25% right is dominant.
VERTEBRAL ARTERY
A. PREVERTEBRAL SEGMENT: Enters
transverse foramina at C6, only muscular
branches.
B. CERVICAL SEGMENT: Anterior
meningeal artery.
C. ATLANTIC SEGMENT: exits through
transverse foramina of atlas till it peierces dura
to enter cranial cavity. Branch: Post.
Meningeal.
D. INTRACRANIAL SEGMENT:
INTRACRANIAL SEGMENT
•
•
Ascends anteriorly + laterally around medulla to
reach midline at pontomedullary junction and forms
basilar artery with other vertebral a at clivus.
BRANCHES:
1.
2.

ANTERIOR + POSTERIOR SPINAL A.
PICA
BASILAR ARTERY BRANCHES:
1.
2.
3.
4.
5.
AICA
INTERNAL AUDITORY A.
SUPERIOR CEREBELLAR A.
POSTERIOR CEREBRAL A.
MEDULLARY AND PONTINE PERFORATING
ARTERIES
POSTERIOR 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:
– Origin to PCOM.
– Posterior thalamoperforators
• P2 SEGMENT:
– Distal to PCOM
– Thalamogeniculate
– Posterior choroidal arteries.
• TERMINAL CORTICAL BRANCHES.
ARTERIAL ANASTOMOSES OF
BRAIN
A.
AT BASE OF BRAIN:
I. CIRCLE OF WILLIS
II. DEVELOPMENTAL ANOMALIES: (3
transient carotid-basilar anastomoses appear
in fetal life)
•
•
•
Primitive hypoglossal artery
Primitive acoustic artery
Persistent primitive trigeminal artery
CIRCLE OF WILLIS
• Complete in 25%,
incomplete in 75%.
• Made by
– Supraclinoid ICAs
– A1 segment of ACA
– ACOMs
– PCOMs
– P1 segment of PCAs
ARTERIAL ANASTOMOSES OF
BRAIN
B. VIA SURFACE VESSELS:
•
•
LEPTOMENINGEAL ANASTOMOSES OF
CEREBRUM:
ACA
 MCA  PCA
OF CEREBELLUM:
SUP CEREBELLAR AICA  PICA.
C. RETE MIRABILE:
•
ECA MIDDLE MENINGEAL/SUP
TEMPORAL A.
LEPTOMENINGEAL ACA/MCA.
NORMAL VARIANTS OF VASCULAR
ANATOMY
• ICA:
– PERSISTENT EMBRYONIC ARTERIES
– ABERRANT PETROUS PART ICA: Courses posterolateral
• ECA:
– MIDDLE MENINGEAL FROM OPHTHALMIC
– VARIATION IN ORDER OF BRANCHING.
• CIRCLE OF WILLIS:
– HYPOPLASTIC PCOM
– HYPOPLASTIC OR ABSENT A1 SEGMENT
– FETAL PCA(FROM ICA) WITH ATRETIC P1
SEGMENT
– HYPOPLASTIC ACOM.
ANTERIOR CEREBRAL ARTERY
MIDDLE CEREBRAL ARTERY
POSTERIOR CEREBRAL ARTERY
CEREBRAL VEINS
THANK YOU