Download Functional anatomy of the external carotid artery systems using

Functional anatomy of the external carotid artery systems
using cross sectional image of rotational digital angiography
Poster No.:
C-1694
Congress:
ECR 2010
Type:
Educational Exhibit
Topic:
Head and Neck
Authors:
Y. Kondo , H. Kiyosue , Y. Hori , H. Mori , S. Tanoue ; Oita/JP,
1
1
1
2
2 1
2
Yufu/JP
Keywords:
Neuroradiology, External carotid artery, Anatomy
DOI:
10.1594/ecr2010/C-1694
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Learning objectives
The objective is to illustrate the functional anatomy of the external carotid artery (ECA)
system using cross-sectional source images of 3-dimensional (3D) digital angiography.
Background
Knowledge of the functional anatomy of the ECA is essential for endovascular treatment
of head and neck lesions. However, it is often difficult to identify the branches of the ECA
in detail because they have complex courses and variations. The anatomical relationships
of the branches with the bony structures in the skull base, including the foramen, spinal
canal or sulcus, are important for their identification. Rotational digital angiography crosssectional images have high resolution and can clearly depict the course of the branches
in relation to the bony structures. In this paper we will demonstrate the 3D functional
anatomy of the ECA systems and present cases with head and neck tumors and vascular
lesions.
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Imaging findings OR Procedure details
Introduction
The external carotid artery (ECA) system, can be classified according to embryology,
into the following three groups; the internal maxillary artery system, derived from
the embryologic hyostapedial artery (second primitive aortic arch derivative), the
thyroid-facial-lingular artery system, derived from the regressed ventral aorta (ventral
pharyngeal artery), and the ascending pharyngeal-occipital artery system, formed
through caroticobasilar anastomoses (Fig. 1 on page 43).
Because embryologic and phylogenetic development closely links the ECA to the
intracranial arteries, there are certain common anastomotic routes, which often follow the
cranial nerves along the neural foramen.
In this paper, we outline the functional anatomy of the main branches of the ECA system
and their anatomical relationships to the skull base, using rotational digital angiography
cross-sectional source images. Knowledge of potentially adverse anastomotic routes and
identification of the cranial nerve supply from the ECA are essential for the clinician to
avoid possible major complications such as embolic stroke or cranial nerve palsy.
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Imaging System and Sample Images (Fig. 2 on page 44)(Fig. 3, click the play button
at the sidebar)
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IQ
Angiography system: Innova3131 Biplane, GE Healthcare, USA
Work station: Advantage workstation VolumeShare2 (AW 4.4), GE
Healthcare, USA
The 3D datasets were obtained from single rotation with a field of view of
20x20 cm using a floor-mounted C-arm.
A total angular range of 200° around patients, with a rotation of 40° per
second during administration of the contrast material (Iopamiron 300; Bayer
Health Care, France)
Injection rates were 21-25 mL at 3.5-4 mL/s, into the common carotid artery
and 12-15 mL at 2 mL/s, into the ECA.
Content
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External Carotid Artery System (meningeal branch) (Fig. 4 on page 45)
1.
Ascending Pharyngeal - Occipital Artery System
1-1. Ascending Pharyngeal Artery
1. Anterior division (pharyngeal branch)
2. Middle division (inferior tympanic artery)
3. Posterior division (neuromeningeal branch)
1-2. Occipital Artery
1. Stylomastoid artery
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2. Mastoid branch
2. Internal Maxillary Artery System
2-1. Middle Meningeal Artery
1. Petrosal branch
i. cavernous branch
ii. petrosal artery
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2. Anterior division
i. lateral branch
ii. meningeal branch
a. Meningolacrimal artery
b. Sphenoidal artery
3. Posterior division
i. petrosquamosal branch
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ii. parieto-occipital branch
2-2. Accessory Meningeal Artery
1. Anterior branch
2. Posterior branch
2-3. Artery of the Foramen Rotundum
(Note) Adverse Anastomoses to the Ophthalmic Artery
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1. Ascending Pharyngeal-Occipital Artery System
1-1. Ascending Pharyngeal Artery
The ascending pharyngeal artery is believed to have developed from the primitive
hypoglossal artery, one of the carotid-basilar anastomoses (Fig. 5 on page 46).
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Course
The ascending pharyngeal artery usually originates from the posterior or medial surface
of the proximal portion of the ECA, and ascends vertically between the internal carotid
artery (ICA) and the side of the pharynx, to below the surface of the base of skull, lying
on the longus capitis. The artery or its branch may also arise from the ICA after its origin
or from the carotid bifurcation. In such cases, its course can follow that of the ICA so that
the guidewire or catheter could be inserted unintentionally into it during angiographical
procedures (Fig. 6 on page 48).
Branches and anastomoses (Fig. 7 on page 48)
The ascending pharyngeal artery divides near the cranial base, into three divisions as
follows:
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- anterior division
- middle division
- posterior division
1. Anterior division (pharyngeal branch)
The anteriorly located pharyngeal trunk gives off three branches as follows (Fig. 8 on
page 49):
- inferior pharyngeal arteries
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- middle pharyngeal arteries
- superior pharyngeal arteries.
The latter, also called the eustachian ramus, constitute the most important anastomotic
routes, and connect with the vidian artery (artery of the pterygoid canal, Fig. 9 on page
50) from the petrous ICA or the distal internal maxillary artery and the accessory
meningeal artery (Fig. 10 on page 51)(Fig. 11 on page 52)(Fig. 12 on page 53).
Finally, this artery gives off a carotid branch which follows the ICA entering the carotid
canal and anastomoses with the recurrent lacerum branch (branch of the lateral clival
artery, which arises from the C5 portion of the carotid siphon) (Fig. 13 on page 54).
This recurrent artery of the foramen lacerum also anastomoses with the posterior branch
of the inferolateral trunk and the cavernous branch of the middle meningeal artery (MMA).
2. Middle division (inferior tympanic artery)
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The inferior tympanic artery is a small branch of the ascending pharyngeal artery, which
passes through a minute foramen in the petrous portion of the temporal bone in tandem
with the tympanic branch of the glossopharyngeal nerve (Jacobson's nerve) to supply
the medial wall of the tympanic cavity. It has potential for anastomosis with the other
tympanic arteries, such as the superior tympanic artery, which arises from the petrous
branch of the MMA, the anterior tympanic artery from the proximal internal maxillary
artery (IMA), the stylomastoid artery from the posterior auricular-occipital artery, and the
carotico-tympanic artery from the ICA (typically these anastomoses are not visualized on
the cerebral angiograms).
3. Posterior division (neuromeningeal branch)
The posterior division is the site of origin of neuromeningeal branches, the hypoglossal
and jugular branches, and enters the cranial cavity through the corresponding foramens
(Fig. 14 on page 55). Both branches give off medial/lateral clival branches immediately
after exiting the hypoglossal and jugular foramen, respectively (Fig. 15 on page 55).
In addition, they also anastomose with mastoid branches of the occipital artery via the
mastoid canal, and the posterior meningeal artery which is from the vertebral artery via
the foramen magnum (Fig. 16 on page 56). The jugular branch distal to the jugular
foramen supplies the dura facing the inferior part of the cerebellopontine angle. The
hypoglossal and jugular branches also supply the adjacent segments of cranial nerves
IX through XII.
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As a remnant of the embryologic hypoglossal artery, the ascending pharyngeal
artery keeps its connection with the vertebral artery via two proximal branches. The
lowest, usually the most proximal branch of the ascending pharyngeal artery, is the
musculospinal branch, which anastomoses laterally with the C3 radicular anastomotic
artery of the vertebral artery. The second branch may contribute to the odontoid arterial
arch, which has a characteristic U-shaped curve, as seen on the lateral view (Fig. 17
on page 57).
1-2. Occipital Artery
The occipital artery is a remnant of the embryologic carotid-vertebrobasilar anastomosis,
namely, type I and type II proatlantal intersegmental arteries (Fig. 18 on page 57).
Full persistence of these segmental arteries is extremely rare; however, the occipital
artery, as their remnant, still retains its connection from the external carotid system to
the vertebral artery.
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Course
The occipital artery generally originates from the posterior surface of the ECA, usually
above the ascending pharyngeal artery, at the level of the angle of the mandible.
However, there are numerous and frequent variations; it may arise from the vertebral,
internal carotid, or ascending cervical artery. It then ascends posteriorly, and passes
deep to the posterior of the digastric muscle in the occipital groove of the temporal bone.
Branches and anastomoses
The occipital artery is divided into three portions as follows:
- first portion: ascending cervical
- second portion: cervico-occipital or horizontal
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- third portion: ascending occipital
The meningeal branches most frequently originate from the second or third arterial
portions (Fig. 19 on page 58). The first portion gives rise to muscular branches, the
auricular branch, and occasionally to the ascending pharyngeal artery.
The posterior anastomotic radicular branches, which are major collaterals from the
vertebral artery to the external carotid system, arise from the horizontal portion of the
occipital arteries at both the C1 and C2 level.
Neural/meningeal branches of the occipital artery
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i. The stylomastoid artery, which may arise from either the posterior auricular or the
occipital artery, passes through the stylomastoid foramen to the tympanic cavity and then
supplies the mastoid portion of the facial nerve (Fig. 20 on page 59).
The artery anastomoses via the superior tympanic artery with the petrosal branch of the
MMA, which supplies the petrosal segment of the facial nerve. Supply of the geniculate
ganglion of the facial nerve is through the facial arcade, which, in most of the cases,
consists of the petrous branch of the MMA and the stylomastoid branch.
Occlusion of the stylomastoid artery during either embolization or surgery may result in
a facial nerve deficit. The stylomastoid artery, when present, marks the position of the
distal part of the facial canal on angiograms.
ii. The mastoid branch, also called the artery of the mastoid foramen, originates from
the horizontal portion of occipital artery. It enters the cranial cavity by passing through
the mastoid foramen (Fig. 21 on page 60).
The mastoid branch emerges intracranially at the posterior border of the upper end of the
sigmoid sinus and divides into three groups of branches:
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- descending
- ascending
- posteromedial
The descending branches are directed toward the jugular foramen and anastomose with
the jugular branch of the ascending pharyngeal artery (Fig. 16 on page 56).
The ascending branches, which are directed to the dura covering the superior part of the
posterior surface of the temporal bone that faces the cerebellopontine angle, anastomose
with the subarcuate branch of the anteroinferior cerebellar artery.
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The posteromedial branches anastomose with the petrosquamous branch of the MMA
and constitute the main supply to the lateral part of the dura matter covering the cerebellar
fossae, which border the hypoglossal branch of the ascending pharyngeal artery and/or
the posterior meningeal branch of the vertebral artery. The small transosseous emissary
arteries can supply the posterior dura matter via emissary canals (Fig. 22 on page
).
The occipital artery thus constitutes a virtual anastomotic crossroads. The nature of its
connection with the vertebral artery must be carefully detailed at the outset of any intraarterial therapy and during the course of the procedure.
2. Internal Maxillary Artery System
Embryology (Fig. 23 on page 61)
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The phylogenesis of the maxillary artery is complicated; by the fifth gestational week, the
stapedial artery arises from the hyoid artery (second aortic arch derivative) originating
at the proximal ICA and extends intracranially forming the obturator foramen of the
stapes. The stapedial artery gives rise to both an upper division and a lower division.
The upper division eventually becomes the MMA and the lower division exits through
the foramen spinosum to become the inferior alveolar and infraorbital arteries. An
anastomosis develops between the lower division and the ventral pharyngeal artery (the
future ECA). The ECA becomes progressively more differentiated as it forms definitive
thyroidal, lingual, occipital and internal maxillary branches. Then the IMA links up with the
maxillomandibular division while the proximal stapedial artery regresses. The derivations
of the end of the stapedial artery form the superior tympanic artery arising from the MMA
and the anterior tympanic artery from the IMA, while the derivative of the embryologic
hyoid artery is the carotico-tympanic artery branching from the petrous portion of ICA.
Thus, the proximal site of the IMA and MMA has a branch toward the tympanic cavity,
suggesting their potential anastomoses via the carotico-tympanic artery with the ICA or
with the stylomastoid artery from the posterior auricular artery or occipital artery.
Course
The IMA is the deep terminal branch of the ECA and is much larger than the superficial
temporal artery. It arises in the parotid gland at the neck of the mandible and extends to
the apex of the pterygopalatine fossa.
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Branches
1. First segment (mandibular segment)
- deep auricular artery
- anterior tympanic artery
- inferior alveolar artery
- MMA
- accessory meningeal artery
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2. Second segment (pterygoid segment)
- anterior deep temporal artery
- posterior deep temporal artery
- buccal artery
- masticator artery
3. Third segment (pterygopalatine segment)
- inferior orbital artery
- descending palatine artery
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- vidian artery
- artery of foramen rotundum
Of the branches listed above, we address the following three most important branches
in terms of endovascular treatment.
2-1. Middle Meningeal Artery
Since the MMA is the most frequent target of transarterial embolization of the ECA,
knowledge of its functional anatomy is essential.
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Course (Fig. 24 on page 61)
The MMA normally arises from the first segment of the IMA, just before the tortuosity
which defines the beginning of the second segment. It enters the cranium through the
foramen spinosum. The MMA gives off a short branch adjacent to the foramen spinosum.
It divides into the petrosal artery laterally and a cavernous branch to the trigeminal
ganglion medially.
The main stem of the MMA courses laterally, along the greater sphenoid wing, where it
branches into its anterior and posterior divisions. Angiographically, in the anterior view,
the MMA is easily recognized by a sharp turn along the floor of the middle fossa after
passing through the foramen spinosum.
Branches and anastomoses
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1. Petrosal branch
i. cavernous branch
ii. petrosal artery
2. Anterior division
i. lateral branch
ii. medial branch
a. meningolacrimal artery
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b. sphenoidal artery (recurrent meningeal artery)
3. Posterior division
i. petrosquamosal branch
ii. parieto-occipital branch
The petrosal branch runs along the greater petrosal nerve and penetrates the temporal
bone by passing through the facial hiatus, supplying the facial nerve and walls of the
tympanic cavity.
The arterial supply of the geniculate ganglion of the facial nerve is through the facial
arcade, which, in most of the cases, consists of the petrous branch of the MMA and
the stylomastoid branch of the posterior auricular artery. In addition, the petrous branch
gives rise to superior tympanic artery, which anastomoses with the stylomastoid artery.
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Attention must be given to the possibility that the petrous branch may supply the
cerebellopontine angle and anastomose with the subarcuate artery from the anterior
inferior cerebellar artery.
The anterior division is distributed to the orbital region (Fig. 25 on page
), to the
floor of the anterior fossa, and to the meninges of the frontal convexity. The supraorbital
artery passes forward through the lateral part of the superior orbital fissure or through
the canal of Hyrtl (cranio-orbital foramen) to anastomose with the lacrimal artery, and
the branches are called the recurrent meningeal artery and the meningolacrimal artery.
Although they supply extraocular tissues such as lacrimal glands, these branches are
well-known for their anastomosis with the lacrimal artery of the ophthalmic artery as
extracranial-intracranial collateral routes. The distal maxillary artery anastomoses with
the inferior branch of the lacrimal artery of the ophthalmic artery through the anterior deep
temporal artery and through the infraorbital artery.
The posterior division gives rise to a petrosquamosal branch at the junction of the
cranial base and convexity. This branch supplies the insertion of the tentorium along the
petrous ridge and groove of the transverse sinus, the dura of the torcula and the junction
of the sigmoid, transverse and superior petrosal sinuses, and extends to the dura of
the posterior fossa. The petrosquamosal artery has anastomoses with the lateral clival
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artery of the ICA, the mastoid branch of the occipital artery or the jugular branch of the
ascending pharyngeal artery (Fig. 26 on page
).
The distal part of the petrosquamosal branch anastomoses with the branches of the
occipital artery, which pass through the mastoid foramen or other emissary canals, at the
level of the junction of the sigmoid, transverse and superior petrosal sinuses, and with
the meningeal branches of the ascending pharyngeal and vertebral arteries. The MMA
may also anastomose with a branch of the basilar artery and dural branch of the posterior
cerebral artery (Davidof artery). The parieto-occipital branch of the MMA supplies the
posterior dura.
2-2. Accessory Meningeal Artery
The accessory meningeal artery mainly supplies the membranous portion of the
Eustachian tube and external acoustic meatus and the lateral pharyngeal wall. It has
been suggested that it be called the pterygomeningeal artery, because the extracranial
structures receive the predominance of its flow, whereas the intracranial branch receives
only 10%.
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Course
The accessory meningeal artery may arise from either the maxillary or middle meningeal
artery. In 60-78% of cases, the accessory meningeal artery enters the cranium through
the foramen ovale. In the remaining 22%, it passes through the sphenoidal emissary
foramen (foramen of Vesalius) (Fig. 27 on page 64).
Branches and anastomoses
The artery passes forward to the lateral pterygoid plate and divides into two branches:
1. Anterior branch
2. Posterior branch
Page 29 of 72
The anterior branch runs along the Eustachian tube to its pharyngeal end and supplies
the mucosa and muscles (Fig. 28 on page 65). It anastomoses with the vidian artery
and the superior pharyngeal branch of the ascending pharyngeal artery.
The posterior branch is meningeal and passes through the foramen ovale, running
anterior to the mandibular nerve. It supplies the lateral wall of the cavernous sinus, the
region of the Gasserian ganglion and adjacent middle fossa dura, where it anastomoses
with the meningeal branches from the ophthalmic artery and MMA and the carotid siphon
(inferolateral trunk). The intracranial portion of the accessory meningeal artery has a
reciprocal relationship with the inferolateral trunk of the intracavernous carotid in the
supply of the mandibular nerve and the dura adjacent to the cavernous sinus. It has
prominent anastomoses with the posterolateral branch of the inferolateral trunk (Fig. 29
on page 66).
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2-3. Artery of the Foramen Rotundum
The artery of the foramen rotundum arises from the termination of the IMA and runs
alongside the maxillary nerve, passing through the foramen rotundum (Fig. 30 on page
67)(Fig. 31 on page 67). As mentioned earlier, it connects with the branches of
the inferolateral trunk of the intracavernous ICA. Thus, it forms an important anastomotic
pathway between the arteries of the cavernous region and the termination of the IMA in
the pterygopalatine fossa.
(Note)
Adverse anastomoses of the ophthalmic artery
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The ophthalmic artery usually arises from the intradural ICA (Fig. 32 on page 68), and
an extradural origin has also been identified. An ophthalmic artery originating from the
MMA has been recognized as a rare anomaly. The ECA system forms a rich vascular
network around the orbit with potential for an anastomotic pathway with the ophthalmic
artery (summarized in Table 1 on page 69). The most important risk for embolization
within this region is occlusion of the central retinal artery (CRA), which results in visual
impairment and blindness of the patient. In addition, embolic stroke could occur through
retrograde filling of the ICA (Fig. 33 on page 68).
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Images for this section:
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Fig. 1: Diagram to show the origin of the main cranial arteries (left) crown-rump(C.R.)
length 7- to 12-mm stage of development. SOB: supraorbital branch, IOB: infraorbital
branch, MB: mandibula branch, VPA: Ventral pharyngeal artery, PMA: primitive
mandibular artery (right) C.R. length 20- to 24-mm stage. Sup.TA: superior tympanic
artery, Ant TA: anterior tympanic artery, CTA: caroticotympanic artery, MMA: middle
meningeal artery, IMA: internal maxillary artery
Fig. 2: 2D Digital angiography(DA) (left) and thin-section maximum intensity
projection(MIP) (right) obtained from the external carotid 3D rotational digital angiography
(lateral view) using a C-arm mounted flat- panel detector(FPD) in a patient with cavernous
sinus dural arteriovenous fistula. Although the both images could show the fistulous point
(arrow), its anatomic details are still unclear.
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Fig. 3: A slideshow movie with the serial source images of the right common carotid
3D rotational digital angiography using a C-arm mounted FPD in a patient with right
cervical internal carotid artery stenosis. ECA; external carotid artery, ICA; internal carotid
artery, FA; facial artery, LA; lingual artery, APA; ascending pharyngeal artery, PhB;
pharyngeal branch (of the APA), OA; occipital artery, PAA; posterior auricular artery,
NMB; neuromeningeal branch (of the APA), HGB: hypoglossal branch (of the APA), JB;
jugular branch (of the APA), AMA: accessory meningeal artery, IMA: internal maxillary
artery, MMA: middle meningeal artery
Page 45 of 72
Fig. 4: Diagram to show the distribution and reciprocal anastomotic pattern of the
meningeal arteries at the skull base. AFR: artery of foramen rotundum, AMA: anterior
meningeal artery, HGB: hypoglossal branch (ascending pharyngeal artery), IMA: internal
maxillary artery, ILT: inferolateral trunk, JB: jugular branch (ascending pharyngeal artery),
LCA: lateral clival artery, MCV medial clival artery, MB: mastoid branch (occipital artery),
MMA: middle meningeal artery, PB: petrosal branch, PMA: postenior meningeal artery
(vertebral artery), PSB: petrosquamous branch, RFL: recurrent artery of foramen lacerum
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Fig. 5: A case with the persistent primitive hypoglossal artery (arrows) arising from the
left ICA, which is demonstrated on MRA.
Fig. 6: An ascending pharyngeal artery branching from the lower portion of the ECA. Left
common carotid angiogram of the patient with anterior condylar vein dural AVF shows the
ascending pharyngeal artery trunk branching from the extremely lower portion of ECA,
whose course is similar to that of ICA on both the frontal(A) and the lateral(B) view (green
arrow heads). It is dilated as a feeding artery of the dural AVF.
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Fig. 7: Diagram of the anastomotic routes via the vidian artery(VA) between the superior
pharyngeal branch(SPB) of the ascending pharyngeal artery(APA), the accessory
meningeal artery(AMA) and the distal internal maxillary artery. AFR: artery of the
foramen rotundum, AMA: accessory meningeal artery, APA: ascending pharyngeal
artery, CB: carotid branch, IOA: infraorbital artery, MMA: middle meningeal artery, NMT:
neuromeningeal trunk, OA: occipital artery, SPB: superior pharyngeal branch, VA: vidian
artery
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Fig. 8: Selective ascending pharyngeal angiogram of a patient with anterior condylar vein
dural AVF immediately after transvenous embolization in lateral view ( * indicates coil
mass).
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Fig. 9: The vidian artery(arrows) passing through the vidian canal (pterygoid canal)
anteriorly into the pterygopalatine fossa(*) is clearly delineated on the cross-sectional
source image of the 3D-DA.
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Fig. 10: The anastomotic routes between the superior pharyngeal branch(SPB) of the
ascending pharyngeal artery and the vidian artery(arrows) are demonstrated on the
reconstructed sagittal source image of the 3D-DA.
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Fig. 11: The superior pharyngeal branch(arrows) of the ascending pharyngeal artery
connecting with the vidian artery arised from petrous portion of the ICA(arrow head)
and the pterygovaginal artery (pharyngeal branch of the internal maxillary artery, black
arrows) are demonstrated on the reconstructed sagittal source image of the 3D-DA.
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Fig. 12: The anastomotic routes via the vidian artery(arrows) through the vidian canal
(pterygoid canal) are demonstrated on the reconstructed sagittal source image of the
3D-DA.
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Fig. 13: The recurrent artery of the foramen lacerum(arrow head), which is a branch
of the lateral clival artery, is demonstrated on axial (A) and reconstructed sagittal (B)
source image of the 3D-DA. It has potential anastomotic routes with the carotid branch
of the ascending pharyngeal artery, the posterior branch of the inferolateral trunk and the
cavernous branch of the middle meningeal artery(MMA).
Fig. 14: The neuromeningeal trunk(*) divides into the hypoglossal branch(HB) and the
jugular branch(JB), entering the cranial cavity through corresponding foramen.
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Fig. 15: A patient with the cervical ICA stenosis. The anastomosis between the jugular
branch(JB) and the medial/lateral clival artery(MCA/LCA) is seen on the source image
of the 3D-DA.
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Fig. 16: The same case as Fig. 15. The anastomosis between the hypoglossal
branch(HB) and the mastoid branch(arrow heads) of the occipital artery(OA) is seen.
Fig. 17: Odontoid arterial arch (A) A patient with right ICA stenosis. The odontoid
arterial arch(arrowheads) is clearly shown on the source image of the 3D-DA. (B) Right
occipital angiogram of the patient with ipsilateral cerebellar hypervascular tumor shows
the anastomosis from the neuromeningeal branch of the ascending pharyngeal artery
to the vertebral artery via the odontoid arterial arch(arrows). It has a characteristic Ushaped curve, as seen on the lateral view(right).
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Fig. 18: A case with the type# proatlantal intersegmental artery(arrows) arising from the
left ICA, which is demonstrated on MRA.
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Fig. 19: Occipital angiogram of a patient with sigmoid sinus dural AVF shows dilated
mastoid branch(MB) via the mastoid canal and meningeal branches of the occipital
artery, including the posterior anastomotic radicular branch(arrows). The neuromeningeal
trunk(NMT) of the ascending pharyngeal artery also supplies the dural AVF.
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Fig. 20: The stylomastoid artery(arrows) arised from the posterior auricular artery(PAA)
passing through the stylomastoid foramen (*) to the tympanic cavity is depicted on the
source images of the 3D-DA. SP: styloid process, OA: occipital artery
Fig. 21: The mastoid branch(arrow heads) of the occipital artery(OA) passing through
the mastoid foramen is demonstrated on axial (A) and reconstructed oblique sagittal (B)
source image of the 3D-DA.
Fig. 22: A patient with left transverse-sigmoid sinus dural AVF. The source images of
the 3D-DA demonstrate the anastomoses between the mastoid branch (red arrowhead)
of the occipital artery and the petrosquamousal artery (green arrows) of the middle
meningeal artery. The small transosseous emissary arteries also enter the cranium via
emissary canals to supply lateral/posterior part of dura matter.
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Fig. 23: Diagram to show the embryologic development of the ECA system with
regression of the Hyo-Stapedial artery. (left) crown-rump(C.R.) length 7- to 12-mm stage
of development. SOB: supraorbital branch, IOB: infraorbital branch, MB: mandibula
branch, VPA: Ventral pharyngeal artery (right) C.R. length 20- to 24-mm stage. Sup.TA:
superior tympanic artery, Ant TA: anterior tympanic artery, CTA: caroticotympanic artery,
MMA: middle meningeal artery, IMA: internal maxillary artery
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Fig. 24: The MMA enters the cranium through the foramen spinosum(red arrow head),
and then divides into petrosal branch, anterior division and posterior division. The
covernous branch is clearly demonstrated(green arow heads) on the source image of the
3D-DA in a patient with right cervical ICA stenosis.
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Fig. 25: The anterior division of MMA distributing to the orbital region is seen on the
source images of the 3D-DA. The recurrent meningeal artery is noted(*).
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Fig. 26: 3D-DA source image (the same parient as Fig. 22.) demonstrates the
petrosquamousal branch(green arrows) anastomosing with the mastoid branch of
the occipital artery and the jugular branch of the ascending pharyngeal artery(red
arrowheads).
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Fig. 27: An accessory meningeal artery (AMA) entering the cranium through the
sphenoidal emissary foramen (foramen of Vesalius) is demonstrated on the source image
of the 3D-DA.
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Fig. 28: The anterior branch of the accessory meningeal artery (AMA) running along the
Eustachian tube is shown on the source image of the 3D-DA.
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Fig. 29: A patient with left cavernous sinus dural AVF supplied from the cavernous
branch of the MMA and the artery of the foramen rotundum. The posterior branch of the
accessory meningeal artery (AMA) passing through the foramen ovale(arrowhead) has
anastomose with the inferolateral trunk to supply the lesion.
Fig. 30: The artery of the foramen rotundum(green arrows) are depicted on the source
images of the 3D-DA in a patient with right cervical ICA stenosis. It anastomoses with
the inferolateral trunk of the intracavernous ICA.
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Fig. 31: A patient with left cavernous sinus dural AVF ( the same as Fig. 29). The foramen
rotundum and th vidian canal (pterygoid canal) and the corresponding arteries are easily
identified on reconstructed coronal source image of the 3D-DA.
Fig. 32: Diagram(A) and MIP images on axial(B) and sagittal(C) view of the ophthalmic
artery from the source image of the 3D-DA.
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Fig. 33: A patient with right cervical ICA stenosis. Right common carotid angiogram
shows anastomosis between the MMA and the ophthalmic artery through the lacrimal
system with retrograde filling to the ICA(arrows).
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Fig. 34: Table 1: Summary of the branches of the ophthalmic artery and their
anastomoses to the ECA.
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Conclusion
The cross-sectional source images of 3D digital angiography(3D-DA) provide a high
spatial resolution, thus allowing a reliable visualization of the meningeal branches of the
external carotid artery systems in relation to fine osseous structures along the skull base.
Knowledge of the potential anastomotic routes between the extracranial and intracranial
arteries is essential for the neurointerventionalists.
Personal Information
Yayoi Kondo Department of Radiology, Nagatomi Neurosurgical Hospital, 2-1-20,
Nishi-Omichi, Oita-city, Japan.
mail to: [email protected]
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