Singapore Med J 2010; 51(2) : e40
C a s e R e p o r t
College of Medicine
3 Jalan Greentown,
Thwin SS, MBBS,
Myint M, MBBS,
Than M, MBBS,
Lwin S, MBBS,
Soe MM, MBBS,
Dr San San Thwin
Tel: (60) 165 577 572
Fax: (60) 5 243 2636
Variations of the origin and branches of
the external carotid artery in a human
Thwin S S, Soe M M, Myint M, Than M, Lwin S
We report a unique variation in the origin and
branches of both the left and right external
carotid artery (ECA) found during the dissection
of a human cadaver. Knowledge of possible
anatomical variations of the ECA is especially
important in facio-maxillary and neck surgeries.
Surgeons need to be aware of the possibility of
encountering such variations, as they may lead to
difficulties in differentiating between the external
and internal carotid arteries, and in identifying
the branches and origins. This knowledge is
also important for radiologists in the image
interpretation of the face and neck regions.
Keywords: ascending pharyngeal artery, external
carotid artery, linguofacial trunk, occipito-
auricular trunk, superior thyroid artery
Singapore Med J 2010; 51(2): e40-e42
Knowledge of the variations of the external carotid
artery (ECA) is essential for facio-maxillary surgery
and surgery of the neck. It is important for surgeons to
differentiate between the ECA and the internal carotid
artery (ICA) to ensure that the artery being ligated
is the ECA, as the ligation of the ICA can result in
hemiparesis. Equally important is the awareness of
variation, such as the bilateral or unilateral absence
of the external carotid arteries, and the understanding
of the abundant anastomoses between the branches
of the ECA and ICA, which provide the collateral
pathways for cerebral perfusion when significant
disease is present in the ICA. This knowledge can help
radiologists to understand and interpret carotid system
imagings, which is essential for cerebral angiography.
We report a rare variation involving both the common
carotid artery (CCA) and ECA on both sides.
Unique anatomical variations involving both the left and
right ECA were found during the dissection of a human
cadaver. These variations included: a relatively high
bifurcation of the CCA on both sides, and on the right
side at the 2nd cervical vertebral (CV2) level and left
side at the 3rd cervical vertebral (CV3) level (Fig.1);
Fig. 2 Photograph shows high origin of the right superior
thyroid artery and simultaneous branching of the right ECA
into the lingual, facial, occipito-auricular and distal part of the
Fig. 1 Photograph shows high bifurcation of the left common
distal part of
right external carotid artery
right facial artery
right lingual artery
right superior thyroid artery
Singapore Med J 2010; 51(2) : e41
high origin of the right superior thyroid artery at the level
where the ECA starts (Fig. 2); simultaneous branching of
the right ECA into the lingual, facial, occipito-auricular
and distal part of the ECA, after giving off the superior
thyroid artery (Fig. 2); common linguofacial trunk on the
left side (Fig. 3); common occipito-auricular trunk on
the right side (Fig. 4); and high origin of the ascending
pharyngeal arteries on both sides, lying medial to the
ECA (Figs. 5 & 6).
The CCA usually bifurcates at the level of the 3rd cervical
vertebra (50% right side and 55% left side) and the 4th
cervical vertebra (40% right side and 35% left side).(1,2)
In this case, a relatively high bifurcation of the CCA was
found on the left side below the level of the hyoid bone
(CV3), and on the right side, the bifurcation was at the
level of the hyoid bone (CV2). Such variations in the
bifurcation of the CCA are not uncommon. Bifurcations
Fig. 6 Photograph shows high origin of the left ascending
pharyngeal artery at the level of the linguofacial trunk.
Fig. 3 Photograph shows a common linguofacial trunk on the
Fig. 4 Photograph shows high bifurcation of the common
carotid artery and the presence of the occipito-auricular trunk
on the right side.
Fig. 5 Photograph shows high origin of the right ascending
pharyngeal artery above the lingual artery.
left facial artery
right lingual artery
right facial artery
distal part of
right posterior auricular artery
Singapore Med J 2010; 51(2) : e42
as high as the hyoid bone or the styloid process and
as low as the cricoid cartilage, or within 3.7 cm of its
origin have previously been reported. Bifurcations of
the CCA at the level of the 2nd cervical vertebra (hyoid
bone) and at the 5th cervical vertebral level on the left
side have been reported in 10% and 1% of the cases,
The right ECA branches directly at its origin into
the superior thyroid, lingual and occipital arteries, as
well as into the distal part of the ECA.(2) In the present
case, the right ECA simultaneously branched into the
lingual artery, facial artery, occipito-auricular trunk and
the distal part of the ECA at the same level after giving
off the superior thyroid artery. Zümre et al in their study
on human foetuses found a linguofacial trunk in 20%,
a thyro-lingual trunk in 2.5% and a thyro-linguofacial
trunk in 2.5% of the human foetuses studied.(3) In this
case, a similar common linguofacial trunk was seen on
the left side. A common occipito-auricular trunk dividing
into the occipital and posterior auricular arteries was
also observed, similar to that reported by Zümre et al in
12.5% of the human foetuses studied.(3)
Bannister et al reported that the ascending pharyngeal
artery (APA) arose deep to other branches and near the
commencement of the ECA.(4) Sinnatamby also found
that the APA arose at the commencement and deep to the
ECA.(5) According to Drake et al, the APA is the second
and smallest branch arising from the posterior aspect of
the ECA.(6) However, in this case, the APA on both sides
were found to arise at a higher level and from the medial
aspect deep to the ECA. On the right side, the APA was
seen to arise at the level of the linguofacial trunk, and on
the left side it arose above the level of the lingual artery.
Anil et al have also reported a variation of the right APA,
which was observed to be arising from the bifurcation of
Variations of the origin and branches of the ECA
on both sides are rare findings and impart important
knowledge that is especially useful for surgeons who
operate on the face and neck regions, as well as for
radiologists in the interpretation of imagings.
We would like to thank the Dean, Prof Dr Hashami, the
Deputy Dean, Dato’ Dr Shafie, Mr Thian, Mr Shamsul,
and all the administrative and academic staff of Universiti
Kuala Lumpur Royal College of Medicine Perak,
Malaysia, for their strong support, as well as Mr Nizam,
Mr Das and Mr Safian of the Anatomy Department for
their assistance during the dissection.
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common carotid artery, anomalous origin of ascending pharyngeal
artery and anomalous branching pattern of external carotid artery.
Surg Radiol Anat 2001; 23:123-5.
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Investigation of the bifurcation level of the common carotid artery
and variations of the branches of the external carotid artery in
human fetuses. Ann Anat 2005; 187:361-9.
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