brief description about vascular anatomy of head and carotid artery

1. VASCULAR ANATOMY OF HEAD,
INTERNAL CAROTID ARTERY
AND EXTERNAL CAROTID
ARTERY BRANCHES
DR.KAMAL ADHIKARI
1st YEAR RESIDENT RADIODIAGNOSIS

2.  COMMON CAROTID ARTERY
 EXTERNAL CAROTID ARTERY
 INTERNAL CAROTID ARTERY
 VERTEBRO-BASILAR SYSTEM
 CIRCLE OF WILLIS
 CEREBRAL VENOUS SYSTEM

3. origin: branch of the aorta (left) and
brachiocephalic trunk (right)
course: posterior to sternoclavicular joint,
lateral to thyroid and trachea
supply: head and neck
termination: at the carotid bifurcation to form
the external and internal carotid arteries
key relationships: internal jugular vein and
vagus nerve
COMMON CAROTID ARTERY

6. Carotid angiogram

7. origin: bifurcation of the common carotid
artery
course: under the submandibular gland and
into the parotid gland
supply: neck, face and base of skull
termination: division into (internal) maxillary
artery and superficial temporal artery
EXTERNAL CAROTID ARTERY

8. Branches of ECA
• Superior Thyroid Artery
• Lingual Artery
• Facial Artery
• Ascending Pharyngeal Artery
• Occipital Artery
• Posterior Auricalar Artery
• Internal Maxillary Artery
• Superficial Temporal Artery

9. SUPERIOR THYROID ARTERY
• origin: branch of the external carotid artery at the level of the hyoid
bone
• supply: larynx and thyroid gland
• termination: thyroid gland
• variants:
• origin at the level of the carotid bifurcation (20%)
• origin from the common carotid artery (10%)

10. LINGUAL ARTERY
• origin: branch of the external carotid artery at the level of the C3
• supply: oral floor and tongue
• termination: tongue

11. FACIAL ARTERY
• origin: branch of the external carotid artery a little above the level of the
lingual
• Branches:
1)cervical:Ascending palatine artery
tonsillar branch
submental artery
glandular branches
2)facial:inferior and superior labial
lateral nasal branch
termination: anterior face as angular artery (terminal branch)

12. ASCENDING PHARYNGEAL ARTERY
• origin: branch of the external carotid artery
• supply: base of skull; anastamosis with anterior and posterior
cerebral circulations
• termination: base of skull

13. OCCIPITAL ARTERY
origin : branch of the external carotid artery at the level of the posterior belly of
digastric
course :ascends posteriorly towards the occiput
termination : scalp over occipital bone
POSTERIOR AURICULAR ARTERY
origin: branch of the external carotid artery above digastric and stylohyoid
opposite the styloid process
course: ascends beneath the parotid toward the ear
supply: scalp and auricle
termination: scalp posterior to auricle

14. INTERNAL MAXILLARY ARTERY
 Larger terminal branch; origin behind the neck of the mandible.
 Course: divided into 3 parts by the lateral pterygoid muscle
 Passes anteriorly, deep to the neck of the mandibular condyle (1st or
mandibular part)
 Passes between the temporalis and lower head of the lateral pterygoid muscle
( 2nd or pterygoid part)
 Passes between the upper and lower head of lateral pterygoidto enter the
infratemporal fossa ( 3rd or pterygopalatine part)
 Termination: sphenopalatine artery

15. Wide distribution
•Ext and middle ears and
auditory tubes.
•Dura mater
•Upper and lower jaw
•Muscles of temporal and
infratemporal fossa
•Nose and PNS
•Roof of pharynx

16. MIDDLE MENINGEAL ARTERY
• Branch of Ist part of IMA.
• Of all the branches of IMA, MMA is very imp neuroradiologically –
commonest source of EDH, a surgical emergency.
• MMA enters the cranial cavity together with accompanying veins
through foramen spinosum.
• Course in cranial cavity: forwards and laterally then terminates into
terminal branches
• Supplies the dura matter and bone of cranium.

17.  Frontal branch:
 Larger
 Forwards and laterally upto lateral end of lesser wing then parallel and ant
to the central sulcus.
 More vulnerable to injury than parietal branch
 Parietal branch
 Runs backwards over or near the superior temporal sulcus

18. PTERION
FRONTAL BRANCH
PARIETAL BRANCH

19. INTERNAL CAROTID
ARTERY
• Assumes
posterolateral
course off the
carotid bulb.

20. There are 7 segments in the Bouthillier
classification:
• cervical segment
• petrous segment
• lacerum segment
• cavernous segment
• clinoid segment
• ophthalmic (supraclinoid) segment
• communicating (terminal) segment

21. BRANCHES
• C1 : cervical segment - none
• C2 : petrous segment
• caroticotympanic artery
• vidian artery
• C3 : lacerum segment - none
• C4 : cavernous segment
• meningohypophyseal trunk
• inferolateral trunk
• C5 : clinoid segment - none
• C6 : ophthalmic segment
• ophthalmic artery
• superior hypophyseal artery
• C7 : communicating segment
• posterior communicating artery
• anterior choroidal artery
• anterior cerebral artery
• middle cerebral artery

23. CERVICAL SEGMENT
 No branches, but
occasionally the ascending
pharyngeal or other
branches of the external
carotid may arise from it
 Also the rare proatlantal
intersegmental artery and
the hypoglossal artery may
arise from it.
 No narrowing and dilations

24. CERVICAL SEGMENT
 Courses posterolateral first
and then posteromedial to
ECA
 Sometimes show a
prominent loop as it lies
lateral to oropharynx , k/a
the TONSILLAR LOOP.

25. PETROUS SEGMENT
 Intraosseous segment in petrous
temporal bone
 Begins where ICA enters carotid
canal
 Ends at the posterior edge of the
foramen lacerum
 BRANCHES
 Vidian artery- inconstant branch;
artery to pterygoid canal
 Carotico-tympanic artery-
supplies middle and inner ear.

26. VARIANTS AND ANOMALIES OF PETROUS SEGMENT
 Aberrant ICA- Traverses
posterolaterally and present
as a pulsatile retrotympanic
mass.
 Persistent stapedial artery(
PSA) is rare. Caused by
intrapetrous embryonic
vascular channels.

27. LACERUM SEGMENT
C3
 Courses above but not
through the exocranial
foramen lacerum, and
contains the lateral loop
of the ICA , and
ascends in the vertical
canal of the of the
foramen lacerum
toward the posterior
carvernous sinus.
 Ends at the superior
margin of the
petrolingual ligament

28. CAVERNOUS SEGMENT (C4)
 Distal to petrolingual
ligament, ICA enters
cavernous sinus
 Usually has a vertical portion,
a posterior bend, a horizontal
portion, and an anterior bend
 Ends at the proximal dural
ring, which incompletely
surrounds the ICA
 Normal ICA forms a loop as it
lies in the lateral wall of the
cavernous sinus, usually
referred to as the carotid

29. BRANCHES OF CAVERNOUS ICA
 Meningohypophyseal artery( posterior trunk)- arises
near C4/C5 junction.
 Marginal tentorial branch or artery of Bernasconi and
Cassinari
 Dorsal meningeal artery
 Inferior hypophyseal artery
 Inferior cavernous artery
 Supplies wall of cavernous sinus and its contents
 Anastomoses with middle meningeal artery
 Small capsular branches to supply anterior
pituitary gland.

31.  CLINOID SEGMENT C5
 Begins at the proximal dural ring and ends at
the distal dural ring where the ICA becomes
intradural
 Part of the anterior loop of the ICA
 Wedged shaped segment, because the proximal
and dural rings fuse posteriorly at the cavernous
sinus roof.

32. • OPHTHALMIC SEGMENT C6
• Begins at distal dural ring and ends just proximal to
origin of the PCoA
• Branches: ophthalmic and superior hypophyseal
artery

33. SUPERIOR HYPOPHYSEAL TRUNK
 Supply pituitary stalk and gland,optic chiasm and optic
nerve.
OPHTHALMIC ARTERY
 From ant aspect of ICA medial to ant clinoid process.
 In majority origin is intradural
 Course: passes into the orbit via the optic canal
 Branches:supply the orbital content and globe
 DR MCLESSI
-Dorsal nasal artery -Supraorbital artery
-(central) Retinal Artery -Supratrochlear artery
-Muscular artery -Internal palpebral artery
-Ciliary artery
-Lacrimal artery
-Ethmoidal arteries

34.  The artery of falx arises from the
anterior ethmoidal branches and
passes through cribriform plate to
supply the anterior part of the falx
 May be hypertrophied to
supply meningiomas and AV
malformations
 OA branches anastomoses with
maxillary artery branches –
potential for collateral flow in
cases of proximal carotid
occlusion
 Anomalies:
 intracavernous origin
 OA gives MMA in 0.5 % cases
1

35.  COMMUNICATING
SEGMENT C7
 Begins just proximal to the
origin of PCoA and ends at
the ICA bifurcation.
 Two major branches:
PCoA and Anterior
choroidal artery

36. POSTERIOR COMMUNICATING ARTERY
 From post aspect of
intradural ICA just below
AChA
 Connects anterior
circulation with posterior
circulation
 Courses post-laterally
above the CN III to join
PCA
 Branch: Ant
thalamoperforating arteries
 Supply: part of optic
chiasm; thalamus ;
hypothalamus; pituitary
stalk and mammilary

37.  Sometimes the origin, as seen in lateral view, is
slightly expanded, k/a infundibulum of the
PCoA(normal variant)
 May be assassociated with defect in the vessel
and predisposes to aneurysm formation
 Common anomaly:
 Hypoplasia( one third cases)
 Junctional dilatation at PCoA origin in 6%.

38. ANTERIOR CHOROIDAL
ARTERY
 Arises from the posterior aspect
of ICA just distal to the origin of
PCoA.
 Course: directed backward and
medially to the medial aspect of
the anterior part of the temporal
lobe – passes round the uncus
and turns laterally and backward
into the choroidal fissure to enter
the temporal horn
 Supplies the choroid plexus,part
of hippocampus,posterior limb of
IC

39. ANTERIOR CEREBRAL ARTERY
 Smaller of the two terminal branches
 Supplies the medial part of the frontal and the
parietal lobe and the anterior portion of the corpus
callosum,basal ganglia and internal caplsule.
 Passes medially to reach the midline, near the
midline joined by the ACoA to its fellow on the
opposite side, then turns forward and upward in the
interhemispheric fissure, then around the anterior
aspect of the corpus callosum and turns backward
along its upper surface

41. • divided into three
segments:
• A1 : origin from the
ICA to the anterior
communicating artery
(ACOM).
• A2 : from ACOM to
the origin of the
callosomarginal artery
• A3 : distal to the
origin of the
callosomarginal
artery

42. A1 segment
 From ICA bifurcation to ACoA
 Courses horizontally from lateral to medial
direction.
 Perforating branches :
- the recurrent artery of Heubner-supplies
the head of caudate nucleus,paraterminal
gyrus,anterior portion of lentiform nucleus
and anterior limb of internal capsule
- medial lenticulostriate artery-supply globus
pallidus and medial portion of the putamen

43. A2 SEGMENT
 ACoA junction to origin of the callosomarginal
artery
 Courses cephalad and curves around the genu
of CC and gives terminal branches
 Branches
 Frontopolar artery
 Supplies orbital gyri,inferomedial portion of
frontal lobe,lateral orbitofrontal cortex

44. CORTICAL BRANCH AND VASCULAR TERRITORY
 Callosomarginal artery
 One of the two terminal branches
 In callosomarginal sulcus (while in the sulcus, it
may be lateral to the midline, sud not be mistaken
for a true displacement by a mass)
 Gives numerous branches (anterior, middle and
posterior internal frontal branches), and
terminates in the paracentral branch around the
paracentral lobule

45. • Pericallosal artery
• Continuation of ACA after it has given off
callosomarginal artery.
• Passes over corpus callosum and terminates in
posterior callosal branch.
• Posteriorly anastomose with splenial artery of PCA
• Territory: Anterior two-third of medial hemisphere
plus small superior area of cerebral convexity.

47. ANTERIOR COMMUNICATING ARTERY
 Connects bilateral
anterior circulations
 Gives small perforating
branches supplying
 Cingulate gyrus
 Anterior columns of the
fornix
 Optic chiasma
 Lamina terminalis
 Hypothalamus
 Paraolfactory areas
 Common location for
cerebral aneurysms

48. VARIANTS AND ANOMALIES OF ACA
 Present in almost one-third of anatomic
dissections
 Common are
1. Hypoplastic or absent A1 seg(5- 18 %)- major part
of the vessel fills from the opposite side through
the ACoA. Sud be distinguished from spasm ass
with subarachnoid hemorrhage
2. Duplicated ACoA( 18 % )
3. Azygos ACA- rare condition (two aca joins to form
a single aca, thus no acoa)
4. Bihemispheric ACA- rare. One side ACA
hypoplastic. Other side gives branches to
contralateral hemisphere.

49. MIDDLE CEREBRAL ARTERY
 Larger of the two terminal branches.
 Supplies most of the temporal lobe, anterolateral
frontal lobe, and parietal lobe
 Major segments
 Horizontal ( M1) segment
 Insular( M2) segment
 Opercular ( M3) segment

50. M1 SEGMENT
 Origin to bifurcation/trifurcation at sylvian fissure.
 Branches:
 lateral lenticulostriate arteries supplying lentiform
nucleus, parts of IC and caudate nucleus.
 Anterior temporal
 Orbitofrontal

51. LENTICULOSTRIATE ARTERIES
 Arise in two groups of 2-4 tiny
arteries(medial and lateral)
 Course: pass upward and medially
for a short distance and then
laterally in an arc that is concave
inward, pass directly up through the
anterior perforated substance into
the basal ganglia and internal
capsule
 Recognised in AP, but usually
obscured in lateral because of
superimposed larger middle
cerebral vessels

52. INSULAR( M2) SEGMENT
 At its genu,MCA divides
into its insular
branch,which loop over
insula and pass laterally to
exit from sylvian fissure.
 Superior and inferior
terminal branches
 Supply: temporal lobe and
insular cortex, parietal lobe
(sensory cortical areas),
inferlolateral frontal lobe

53. OPERCULAR(M3) SEGMENT
 Which gives off
branches that emerge
from sylvian fissure and
ramify over
hemispheric surface.
 The insular and
opercular branches
supply the
temporal,parietal and
variable parts of frontal
and occipital lobes.

55. VARIANTS AND ANOMALIES OF MCA
 Less frequent than other major intracranial arteries.
 Fenestration, duplication, single trunk and accessory
arteries are all uncommon- less than 5%.

56. VERTEBRAL ARTERY
 origin : branch of the subclavian artery
 course :ascends posterior to the internal carotid
artery in the transverse foramina of the cervical
vertebrae
 termination : combines with the contralateral
vertebral artery to form the basilar artery
 key relationships : posterior to the internal
carotid artery; ascends anterior to the roots of the
hypoglossal nerve (CN XII)
 Left VA dominant in 50 to 60 %

59. Segments
V1(preforaminal):origin to transverse foramen of C6
V2(foraminal):from the transverse foramen of C6 to the
transverse foramen of C2
V3(atlantic,extradural or extraspinal):from C2 to dura
V4(intradural or intracranial)from the dura to their
confluence to form basialr artery

60. Branches
1)V1:segmental, cervical ,muscular and spinal
branches
2)V2:anterior meningeal artery,muscular and spinal
branches
3)V3:posterior meningeal artery
4)V4: anterior and posterior spinal arteries,
perforating branches to medulla,
posterior inferior cerebellar artery

61.  The anterior and post spinal arteries are tiny and
difficult to identify, although the anterior spinal artery
is usually visible in a good-quality vertebral
arteriogram ( passing downward into the spinal canal
as a very fine vessel directly anterior to the cord)
 The posterior meningeal artery, when identified, is
seen as a near midline vessel passing upward and
just anterior to the occipital bone in the lateral view

62. VARIANTS AND ANOMALIES OF VA
 Asymmetry due to vertebral artery
hypoplasia,absence or terminations into PICA of one
of the vertebral artery is common.
-dominant left vertebral artery(60%)
-dominant right vertebral artery(25%)
-both vertebra symmetrical (25%)
 Complete or partial vertebral artery duplication
 Vertebral artery fenestration
 Variable origin
-aortic origin of left vertebral artery
-second branch of subclavian artery
-external carotid artery(rare)

63. PICA
 Generally arises as a single trunk from distal VA.
 The point of origin of the artery may be from the
vertebral artery below the foramen magnum or as
high as the junction of vertebral and basilar
arteries. Sometimes it arises from the basilar or in
common with the AICA

64.  Segments
1. Anterior medullary seg - in front of medulla
2. Lateral medullary segment - curves forming the
caudal loop,located anteroinferior to the tip of
cerebellar tonsil
3. Posterior medullary segment – ascends posterior
to the medulla along the posterior medullary velum
4. Supratonsillar segment

65.  Branches:
 Anterior and lateral medullary
segments: small perforating
medullary branches
 Supratonsillar segment:
tonsillohemispheric branch and
inferior vermis branch

66. Supply of PICA
 Posterioinferior cerebellar hemisphere
-cerebellar tonsils
-biventral lobule
-nucleus gracilis
-Superior semilunar lobule
 Inferior portion of the vermis
 Lower part of the medulla
 Inferior cerebellar peduncles

67. BASILAR ARTERY
 Formed by the union of two VAs just above the
foramen magnum
 Course:
 passes upward directly behind the clivus and
terminates behind or just above the tip of the
dorsum sellae
 Runs cephalad in prepontine cistern and
terminates in interpeduncular cistern .
 Lies in the midline, however, displacement
from midline or lateral kinking is quite common
in the middle aged and elderly, particularly in
hypertensive patients.

69.  Branches
 AICA
 Superior cerebellar artery:
 perforating branches along the entire length of BA to
supply ventral pons and rostral brain stem

70. .
 AICA
 Originates within a cm of the origin of the basilar
artery.
 Comes posterolaterally within the CP angle cistern
toward the internal auditory canal.
 supply branches to the internal auditory meatus
and also to the inferior surface of the cerebellum.
 Supply
 CN VII and VIII
 Inferolateral pons
 Middle cerebellar peduncle
 Flocculus
 Anterolateral surface of cerebellum

71. • Superior cerebellar artery:
• Arise just before the termination of the basilar
artery
• Curve round the midbrain to reach the superior
surface of the cerebellum, where they divide into
several branches
• Supply : superior surface of vermis and cerebellum

72. Variants and anomalies of BA
 Persistent embryonic carotid- vertebrobasilar
anastomosis
 Superior cerebellar arteries may arise from PCA or
even directly from ICA

73. POSTERIOR CEREBRAL ARTERY
 Terminal branches of basilar arteries.
 Course: curve around the cerebral peduncles to reach the
dorsal aspect of midbrain. Then pass through the tentorium
to reach the undersurface of the temporal lobes.
 Segments
 P1 : from it origin at the termination of the basilar artery to posterior
communicating artery (PCOM), within interpeduncular cistern.
 P2 : from the PCOM around the mid-brain, divided into P2A
(anterior) and P2P (posterior) sub-segments. P2A is within crural
cistern which then bridges to the P2P segement in ambient cistern
(thus ambient segment)
 P3 : quadrigeminal segment (segment with the quadrigeminal
cistern)
 P4 : cortical segment (e.g., calcarine artery, within the calcarine
fissure)

74. BRANCHES
 medial posterior choroidal
arteries
 lateral posterior choroidal
arteries
 perforators
 anterior thalamoperforator
 posterior thalamoperforator
(from P1)
 thalamogeniculate perforator
(from P2)
 peduncular perforator (from
P2)
 circumflex (long and short)
 temporal branches
 anterior temporal artery
 posterior temporal artery
 lateral occipital artery
 anterior inferior temporal
artery
 middle inferior temporal
artery
 posterior inferior temporal
artery
 medial occipital artery
 calcarine artery
 parieto-occipital artery
 splenial artery

75. VARIANTS AND ANOMALY OF PCA
 Most common is fetal origin of PCA from ICA instead
of basilar artery ( 15 to 20%)
 Carotid-basilar anastomosis

76. ARTERIES TO SPECIFIC AREAS OF BRAIN
 1.Internal Capsule

77. CIRCLE OF WILLIS
 Vessels comprising circle of
Willis
 two ICA
 A1 segment of ACA both
 ACOM
 Two PCOM
 P1 segments of both PCA
 Basilar artery
 Branches of the circle of Willis (supply optic chiasm and tracts,
infundibulum, hypothalamus and other structures at base of brain):
 medial lenticulostriate arteries (from A1 segment of ACA)
 thalamoperforating and thalamogeniculate arteries (from basilar tip,
proximal PCAs and PCOMs)
 perforating branches (from the ACOM)

79. Normal variants:
 Posterior circle anomalies seen in ~50% of
anatomic specimens
 Common:
 Hypoplasia of PCOM (34%)
 Hypoplastic or absent A1
 Fetal origin of PCA from ICA
 Hypoplastic or absent P1 segment
 Infundibular dilatation at PCOM origin (10%)

81. PERSISTENT CAROTID-VERTEBROBASILAR
ANASTOMOSES
 The persistent carotid-vertebrobasilar
anastomoses are named (with the exception of the
proatlantal artery) using the cranial nerves with which
they run.
 Persistent trigeminal artery
 arises from proximal cavernous ICA
 most common persistent carotid-vertebrobasilar anastomosis
 present in 0.1 - 0.6% of cerebral angiograms and is usually
unilateral.
 Vertebral, posterior communicating and caudal basilar
arteries are often hypoplastic.
 There is an association with intracranial aneurysms and
vascular malformations.

82.  Persistent otic (acoustic) artery
 controversial, perhaps non-existent
 arises from petrous ICA and communicates with basilar
artery inferiorly
 rare, as it is the first anastomosis to regress
 Persistent hypoglossal artery
 arises from cervical ICA at C1 to C3 levels
 After passing through an enlarged hypoglossal canal, it
joins the basilar artery inferiorly. If large, the
ipsilateral vertebral artery is often hypoplastic or absent.
 Persistent proatlantal artery
 It arises from the internal carotid artery (similar to
the hypoglossal artery) but instead of heading for
the hypoglossal canal, it joins the vertebral artery through
the foramen magnum.

83. VENOUS SYSTEM OF BRAIN
 Unlike the majority of the rest of the
body,doesnot follow the cerebral arterial system.
 Cerebral venous system is composed of two
components:
1)Dural venous sinuses
2)cerebral veins

85. Venous sinuses

86.  Dural sinuses
1)Superior sagital sinus:situated in the midline and
typically originates near the crista galli anteriorly
and extends posteriorly to its confluence with the
straight and lateral sinuses at torcula
2)Inferior sagital sinus:Situated in inferior free
margin of the falx cerebri and joins the vein of
Galen to form straight sinus

87. 3)Transverse and occipital sinus:the torcula herophili
divides into transverse(lateral)and occipital sinuses
The transverse sinus courses laterally to form
sigmoid sinuss and drain into internal jugular veins
on either side.
Occipital sinus is rudimentry.
4)Cavernous sinuses:largest venous sinuses
Tributaries:superior and inferior ophtalmic veins

88. • Cerebral veins
-Superficial(cortical) veins
-Deep veins
Superficial cortical veins
-variable in number and enter the superior sagital sinus
near the vetrex
Larger veins:superficial middle cerebral veins and veins
of Trolard and Labbe

89. • Vein of Trolard
-passes upward and backward over over the
hemisphere to enter superior sagital sinus in parietal
region
Vein of labbe
-passes horizontally across the temporal lobe to enter
the lateral sinus

91. • Deep cerebral vein:
-The medullary veins originate 1 to 2 cm below the
cortex and course cenrtally towards subependymal
veins which surrounds the lateral ventricles.
-Internal cerebral veins lie on each side of
midline,commences behind the foramen of monro
and passes backward in the roof of third ventricle.

92. • Two smaller vein(septal veins and striothalamic vein)
drain to the internal cerebral vein
• At its posterior end,ICV joins with its fellow of
opposite side and enters into vein of Galen,which
joins the inferior sagittal sinus to form straight sinus.
• Straight sinus usually drains to left lateral sinus
• Superior sagital sinus drains to right lateral sinus

93. • Veins draining posterior fossa:anterior
pontomesencephalic vein,precentral vein,superior
and inferior vermian veins and hemispheric vein

94. THANK YOU