Microsurgical anatomy of the external carotid artery: a stereoscopic

ORIGINAL ARTICLE

Microsurgical anatomy of the external carotid artery: a

stereoscopic study

Anatomia microcirúrgica da artéria carótida externa: um estudo estereoscópico

Gustavo Rassier Isolan

, Adamastor Humberto Pereira

, Paulo Henrique Pires de Aguiar

Ápio Cláudio Martins Antunes

, João Pedro Mousquer

, Marcel Rozin Pierobon

Abstract

Background: Knowledge of the anatomical structures of the external carotid artery by means of stereoscopic study may yield better results in

microsurgery of the external carotid artery.

Objective: To describe the structures of the external carotid artery under stereoscopic view, identifying its multiple aspects.

Methods: e cervical regions of twelve cadavers were dissected using a surgical microscope with 3 to 40 X magniﬁcation. e anatomical dissections

were documented using the technique to obtain three-dimensional images (3D), aiming at producing stereoscopic images.

Results: e use of the stereoscopic technique allowed a tri-dimensional approach to the extracranial arterial circulation, and the performance of

surgical dissections such the combined approach to the posterior fossa and infratemporal fossa, making microvascular surgery and neurosurgical

procedures more precise.

Conclusion: e use of images obtained by the stereoscopic technique produced a more assertive result in relation to the anatomy study for

microsurgical or neurosurgical procedures, allowing better analysis before performing complex neurosurgical procedures.

Keywords: stereoscopic vision; carotid artery, external; three-dimensional images.

Resumo

Contexto: O conhecimento das estruturas anatômicas da artéria carótida externa por meio do estudo estereoscópico pode determinar melhores

resultados em microcirurgias da artéria carótida externa.

Objetivo: Descrever as estruturas da artéria carótida externa sob a visão estereoscópica, identiﬁcando seus múltiplos aspectos.

Métodos: Doze regiões cervicais foram dissecadas, utilizando-se microscópico cirúrgico com 3 a 40X de aumento. As dissecções anatômicas foram

documentadas utilizando-se a técnica para obtenção de imagens tridimensionais (3D), objetivando a produção de impressões estereoscópicas.

Resultados: O uso da técnica estereoscópica possibilitou a abordagem da circulação arterial extracraniana, sendo realizados estudos cirúrgicos do tipo

combinado fossa posterior e fossa infratemporal, tornando as microcirurgias e os procedimentos neurocirúrgicos vasculares mais precisos.

Conclusão: O uso das imagens obtidas pela técnica estereoscópica produziu um resultado mais assertivo em relação ao estudo da anatomia

para a microcirurgia e procedimentos neurocirúrgicos, facilitando melhor aprendizado previamente à realização de procedimentos complexos

em neurocirurgia.

Palavras-chave: visão estereoscópica; artéria carótida externa; imagens tridimensionais.

Study carried out at the Microsurgery Laboratory of the University of Arkansas, Little Rock, USA.

PhD; Professor at the Surgical Science Postgraduate Program of Federal University of Rio Grande do Sul (UFRGS) – Porto Alegre (RS), Brazil.

PhD; Professor at the Vascular Surgery Service of the Clinics Hospital of Porto Alegre; Postgraduated in Surgical Science at UFRGS – Porto Alegre (RS), Brazil.

PhD; Professor at the Neurosurgery Service of the Clinics Hospital of Porto Alegre – Porto Alegre (RS), Brazil.

Medical Student at UFRGS – Porto Alegre (RS), Brazil.

MsD Student; Postgraduated in Surgical Science at UFRGS – Porto Alegre (RS), Brazil.

Financial support: none.

Conﬂict of interest: nothing to declare.

Submitted on: 07.20.10. Accepted on: 08.03.11.

J Vasc Bras. 2011;11(1):3-11.

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al.J Vasc Bras 2011, Vol. 11, Nº 1

Introduction

e external carotid artery presents complex anatomy

that should be known in depth by vascular surgeons, neu-

rosurgeons, head and neck surgeons, among other profes-

sionals. When studied using conventional photographic

images, such anatomy does not show the real depth of

some structures. In order to to mitigate this problem and

to provide a tri-dimensional (3D) perspective in printed

images, the 3D anaglyphic method was created. e pur-

pose of this study is to present detailed results of micro-

surgical dissections of the external carotid artery by means

of stereoscopic imaging.

Material and methods

is study was conducted at the Microsurgery

Laboratory, University of Arkansas, Little Rock, United

States. e cervical region of twelve cadavers were dis-

sected using a surgical microscope of 3 to 40 X magnica-

tion. e cadavers were injected with color silicon and po-

sitioned with a Mayeld skull clamp; the head was stretched

and rotated, simulating the surgical position to approach

the extracranial arterial circulation. en, combined poste-

rior fossa and infratemporal fossa surgical dissections were

performed, that simulated operations for jugular foramen

tumors, as well the simulation of vascular neurosurgical

procedures, such as: endarterectomy and extra- to intracra-

nial arterial anastomosis.

e anatomical dissections were documented using the

technique to obtain 3D images, aiming at the production

of stereoscopic prints. In this technique, pictures are tak-

en of the same object from two dierent positions, but on

the same horizontal plane. e rst position corresponds

tothe le eye view and the second position correspondsto

the right eye view. e images were superimposed, using

a previously dened soware program, coordinated and

printed. A Nikkon D70 camera, 8.0 megapixels with macro

lens was used to document the dissections. e device was

adapted to a sliding bar assembled on a tripod. e lens and

the shutter speed were set at f32 and 1/60 seconds, respec-

tively. e stereoscopic technique employed by the authors

is detailed in a previous study conducted by Ribas et al.

e prints made using the stereoscopic technique should be

viewed with red-green stereoscopic glasses.

Results

e authors described the anatomy based on the stud-

ies conducted by Testut and Latarjet

and Rhoton

e external carotid artery arises from the bifurcation of

the common carotid artery, also called primitive carotid artery;

there is one artery on the right and another on the le side of the

neck. e right common carotid originates from the brachio-

cephalic trunk, at the lower part of the neck, while the common

le carotid starts at the aortic arch, presenting a small intratho-

racic segment, which makes it longer than the right common ca-

rotid. ese arteries run from their origins to the upper border

of the thyroid cartilage, where they bifurcate to form external

and internal arteries.

e common carotid arteries are located in each side of

the antero-lateral region of the neck (carotid region), and are

related posteriorly with the cervical sympathetic chain and

with the transverse apophysis of cervical vertebrae covered by

the prevertebral muscles and the deep cervical aponeurosis.

e transverse apophysis (transverse process) of C

presents a voluminous and palpable tubercle, which is used

as the surgical reference point to access the common ca-

rotid; this prominence is called Chassaignac tubercle. At

this level, the common carotid artery is crossed posteriorly

by the inferior thyroid artery. It is related to the esophagus

and the trachea (tracheoesophageal axis) inferiorly, to the

laringotracheal axis superiorly, to the sternocleidomastoid

muscle anteriorly, and in close contact with the internal jug-

ular vein along all its extension. e vagus nerve is between

these two large caliber vessels.

e common carotid artery, the internal jugular vein and

the vagus nerve form the neurovascular bundle of the neck,

which is wrapped by a very evident sheath, oering an excellent

plane for surgical dissection. is artery bifurcates at the level of

the upper border of the thyroid cartilage, forming the internal

and external carotids. At the bifurcation, the common carotid

artery presents a bulge, known as carotid bulb.

e external carotid artery starts at the level of the upper

border of the thyroid cartilage lamina and ends behind the

neck of the mandible, between the tip of the mastoid process

and the angle of the mandible. It bifurcates inside the parotid

gland forming the supercial temporal artery and the maxil-

lary artery, also known as internal maxillary artery.

Figures 1 to 10 illustrate the external carotid artery

anatomy. e external carotid artery branches are: superior

thyroid artery, ascending pharyngeal artery, lingual artery,

facial artery, occipital artery, posterior auricular artery, su-

percial temporal artery and (internal) maxillary artery.

Superior thyroid artery

e superior thyroid artery starts at the anterior aspect of

the external carotid artery, at the level of the greater cornu of

the hyoid bone. When the common carotid artery bifurcates

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al. J Vasc Bras 2011, Vol. 11, Nº 1

above the usual level, this artery can have its origin at the

carotid bulb. Running a deep anterior and later downward

course , it divides into small branches onto the upper pole of

the thyroid lobe. Along its course, the superior thyroid artery

is in contact with the pharynx and the larynx, below the in-

frahyoid muscles. In this course, it supplies the thyroid gland

with its terminal (anterior and posterior) branches and the

larynx with its collateral (superior laryngeal and cricothy-

roid) branches. e following branches have been identied:

• Infrahyoidbranch:paralleltothelowerborderofthehyoid

bone, it supplies the supra- and infrahyoid muscles.

• Middlesternocleidomastoidartery branch:4to6cm

long, it starts and crosses the common carotid artery

and the internal jugular vein, entering the deep portion

of the sternocleidomastoid muscle, and it is accompa-

nied by a large tributary of the internal jugular vein.

• Superior laryngeal artery: has its origin at the supe-

rior thyroid artery, following an anteroinferior course

to subsequently bifurcate into two terminal branches,

one external and one posterior. e external branch is

behind the terminal branches of the superior laryngeal

nerve and the upper portion of the branch behind the

posterior nerve bundles. e posterior branch runs

posteriorly, closely related to the arytenoid fold.

• Inferiorandposteriorlaryngealarteries:theyrunup-

wards posteriorly to the cricoarytenoid muscle, aer

anastomosing with the posterior portion of the superior

laryngeal branch. ey supply the inferior pharyngeal

constrictor, the ary-arytenoid, posterior cricoarytenoid

and the cricothyroid muscles.

• Terminalbranches:aninternalbranchthataccompanies

the upper border of the thyroid body and that anasto-

moses at the midline with the branch from the opposite

side; an external branch that runs downwards and bifur-

cates over the external portion of the corresponding thy-

roid lobe; and a posterior branch that crosses behind the

thyroid gland, between this gland and the trachea

Figure 1 shows the side view of the external carotid ar-

tery branches and Figure 2 shows the same image, but using

the stereoscopic technique.

Ascending pharyngeal artery

e ascending pharyngeal artery is the only branch

that comes o the posterior face of the external carotid ar-

tery, near or at the same level of the lingual artery. It runs

upwards in contact with the lateral wall of the pharynx and

ends at the base of the skull, entering the jugular foramen

and the hypoglossal canal

It supplies the dura-mater of the inferior clivus region,

and at the same time, it anastomoses with branches of the

dorsal meningeal artery, which starts at the meningohypo-

physeal trunk into the cavernous sinus. ese branches sup-

ply the upper two-thirds of the clivus

(Figures 3 and 4).

Lingual artery

e lingual artery has its origin at the medial aspect

of the external carotid artery, on average 2 cm cephalad

to the carotid bulb, and runs obliquely and anteriorly. It

runs in front of and over the greater cornu of the hyoid

Figure 1. Side view of the external carotid artery branches. 1. superior

thyroid artery; 2. inferior pharyngeal constrictor muscle; 3. thyroid car-

tilage; 4. submandibular gland; 5. lingual artery; 6. hypoglossal nerve; 7.

facial artery; 8. ascending palatine artery; 9. stylohyoid muscle; 10. sty-

loglossus muscle; 11. ascending pharyngeal artery; 12. internal jugular

vein (sectioned); 13. vertebral artery; 14. suboccipital triangle; 15. styloid

process and posterior auricular artery; 16. maxillary artery; 17. infraor-

bitary nerve; 18. buccinator muscle.

Figure 2. Side view of the external carotid artery branches using the

stereoscopic technique.

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al.J Vasc Bras 2011, Vol. 11, Nº 1

bone and runs under the hyoglossal muscle to reach the

anterior portion of the tongue through its terminal branch

(deep lingual artery)

5,6

Along its course, the lingual artery gives o three im-

portant collateral branches:

• Hyoidbranch:itrunsalongthehyoidbone,rstabove

and then below it. It anastomoses with the branch from

the opposed side at the midline, forming an arch locat-

ed between the genioglossus and geniohyoid muscles. It

supplies the insertions of the infrahyoid muscles above

and the stylohyoid branches, at the junction where the

digastric and mylohyoid branches meet.

• Dorsallingualartery:itisusuallyofsmallcaliberand

was identied in only one cadaver. It has an ascending

branch that runs inferiorly, reaching both sides of the

base of the tongue and ending at the mucosa that cov-

ers the caliciform papillae, the anterior arch, the so

palate and the epiglottis.

Sublingual artery: it is a exible vessel in the anatomical

dissections that runs in parallel to Wharton’s duct, between the

mylohyoid and genioglossus muscles. Along its course, it gives

o branches to the sublingual gland and the hyoglossus mus-

cle, branches above the genioglossus and branches below the

geniohyoid muscle before bifurcating into terminal branches:

one superior, towards to middle portion of the horizontal

branch of the mandible and one inferior, which enters the mid-

dle mental canal through the sub and intragenian foramina.

Figure 3. Advanced dissection of the skull base, showing the middle

meningeal artery and its point of penetration into the middle fossa (12),

as well as the cervical internal carotid artery entering the skull base, after

which it is called intrapetrous portion of the internal carotid artery. 1. lat-

eral rectal muscle; 2. V1; 3. V2; 4. V3; 5. trochlear nerve; 6. oculomotor nerve;

7. M2 branches of the middle cerebral artery above the insula; 8. posterior

cerebral artery; 9. Gasserian ganglion; 10. ICA; 11. Eustachian tube; 12. mid-

dle meningeal artery; 13. V3; 14. oropharynx; 15. styloid process.

Figure 4. A) Axial magnetic nuclear resonance in T1 with gadolinium, showing an injury on the right jugular foramen surface, compatible with a paraganglio-

ma; B) arteriography with injection of contrast into the right external carotid artery, showing ﬁlling across the occipital artery (single arrow) and ascending pha-

ryngeal artery (dual arrow), the two vessels were embolized; C) cross-sectional arteriography with catheterization of the right internal carotid artery, showing

a small tumoral blush originated in the carotid-tympanic branches of the intrapetrous portion of the ICA; D) surgical stage showing the previously separated

temporalis muscle; E) dissection and exposure of the neurovascular structures of the neck; F) computed axial tomography in the immediate post-operative

period, showing hypodense material compatible with fat graft inside the mastoid portion of the temporal bone during the skull base reconstruction.

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al. J Vasc Bras 2011, Vol. 11, Nº 1

Facial artery

e facial artery has its origin on average 1.5 cm above

the lingual artery. It runs an ascending and oblique course

anteriorly; initially in contact with the pharyngeal wall, it

passes under the posterior belly of the digastric muscle and

the stylohyoid muscle, entering the anterior groove of the

masseter muscle and crossing the horizontal ramus of the

mandible

. Finally, it runs obliquely upward and forward,

following the nasolabial crease. It ends at the internal angle

of the eye, under the name of angular artery, which anasto-

moses with one of the branches of the ophthalmic artery

e collateral branches of the facial artery are: the cervical

and facial branches (Figures 6 and 7).

Cervical branches

The inferior ascending palatine artery arises from

the facial artery 4 to 5 cm distally to its origin. It runs

anterior e superiorly, passing between the fibers of the

styloglossus muscle. It ascends through the lateral aspect

of the pharynx, gives off a branch to the tongue muscles

and branches off distally to the palatine tonsil, superior

pharyngeal constrictor muscle and stylopharyngeal mus-

cle. It anastomoses with the superior palatine and inferi-

or pharyngeal arteries. The internal pterygoid muscle ar-

tery arises from the inferior palatine, and rarely from the

facial artery, and supplies the internal pterygoid muscle.

The submental artery is a larger vessel, that has its ori-

gin at the facial artery at the level of the submandibular

gland. It runs horizontally along the lower border of the

mandible, between the mylohyoid muscles and the ante-

rior belly of the digastric muscle, supplying several small

branches to these muscles along its course. It ends in the

mental region, where it anastomoses with the terminal

ramifications of the inferior dental arch.

Facial branches

The inferior masseteric artery has this name to be

distinguished from the masseteric artery, which arises

from the internal maxillary artery and is the main sup-

plier to the masseter muscle. The inferior labial artery

arises from the facial artery at the level of the lips. It runs

horizontally into the muscles of the lower lip and it anas-

tomoses at the midline with the same artery from the op-

posite side. The superior labial artery starts at the same

level as the inferior labial artery, but it runs to the upper

lip, where it anastomoses at the midline with the same

artery from the opposite side. The lateral nasal artery

arises from the facial artery at the level of the nose side

and runs forward and inside and bifurcates, almost im-

mediately after its origin, in the three branches, resulting

in slender ramifications to the alae, to the dorsum and to

the lobe. The terminal branches of this artery anastomo-

ses with the same arteries from the opposite side.

Figure 5. Posterior cervical region showing the occipital artery and vein (sin-

gle arrows). Contralateral occipital artery (dual arrow) and C2 dorsal branch.

Figure 6. Side view of the intratemporal fossa. e zygoma and part of

the mandible were removed. 1. facial artery; 2. buccinator muscle; 3. su-

perior posterior alveolar artery; 4. sphenopalatine artery; 5. deep tempo-

ral arteries (anterior and posterior); 6. lateral pterygoid muscle (upper

head); 7. maxillary artery; 8. medial pterygoid muscle (lower head); 9.

buccal nerve; 10. buccal artery; 11. styloid process; 12. medial pterygoid

muscle; 13. lingual nerve; 14. inferior alveolar nerve; 15. external carotid

artery; 16. posterior auricular artery; 17. posterior belly of the digastric

muscle; 18. angle of the mandible; 19. condylar process.

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al.J Vasc Bras 2011, Vol. 11, Nº 1

Occipital artery

It arises from the posterior aspect of the external ca-

rotid artery, near the origin of the facial artery, and runs

posteriorly and upwards to supply the neck region. e col-

lateral branches of the occipital artery are:

• superiorsternocleidomastoidbranch:runstothedeep

sternocleidomastoid muscle;

• muscularbranchesinvariablenumberthataregiven

o at dierent levels of the occipital artery and go to

neighboring muscles;

• stylomastoidbranch:entersthestylomastoidforamen,

in close relation with the facial nerve along its course.

Its ramications go to the eardrum, mastoid cavity and

semicircular canals.

• meningealartery:entersthemastoidforamen,supply-

ing the dura-mater of the mastoid region (Figure 5).

Posterior auricular artery

Also named retroauricular artery, it arises right

above the occipital artery and runs a posterosuperior

oblique course, passing beneath the posterior belly

of the digastric muscle, finally reaching the posterior

border of the mastoid

8,9

It has the following terminal

branches: an anterior branch that supplies the inter-

nal face of the ear and supplies the external face with

small distal branches, called perforators, which supply

the skin of the helix, antihelix, concha and earlobe; one

posterior branch, which spreads in the region behind

the ear, anastomosing with branches from the occipital

and superficial temporal arteries.

Superﬁcial temporal artery

e supercial temporal artery is one of the terminal

branches of the external carotid artery. It arises right above

the mandibular condyle, inside the parotid gland and goes

upward, anterior to the tragus. In its most supercial course,

it passes (between the two fascias of the temporalis muscle)

above the temporalis muscle and the anterior auricular mus-

cle, and divides into two terminal branches: frontal and pari-

etal. e supercial temporal artery is accompanied along all

its course by the supercial temporal vein and partially by the

auriculotemporal nerve

5,6

(Figure 8).

Maxillary artery

e maxillary artery is one of the terminal branches of

the external carotid artery (the other one is the supercial

temporal artery), which arises at the level of the neck of

the mandible and its initial course is inside the parotid

gland

. e maxillary artery is divided into three portions:

mandibular (or retromandibular), pterygoid and pterygo-

palatine. ese subdivisions of the maxillary artery are es-

tablished in relation to the lateral pterygoid muscle

. From

lateral to medial direction, the rst portion is laterally, the

second is at the same level and the third is medially located

in relation to the muscle. In our dissections, the maxillary

artery was lateral to the buccal and lingual arteries and to

the inferior alveolar nerve in all specimens

The branches of the first portion penetrate into fo-

ramens of base of the skull. This segment of the maxil-

lary artery passes between the mandibular condyle and

the sphenomandibular ligament, running alongside the

auriculotemporal nerve. Its branches are: the deep au-

ricular artery, closely related to the wall of the external

acoustic meatus

; the anterior tympanic artery, which

runs parallel to the chorda tympani nerve and enters

the petrotympanic fissure; and the middle meningeal

artery, the first maxillary artery branch that runs super-

ficially to the lateral pterigoid muscle. It may start at a

trunk in common with the inferior alveolar artery, but

this pattern was not observed in our dissections. It as-

cended to enter the spinal foramen; the accessory men-

ingeal artery may start at the medium meningeal artery

and ascends next to the tensor veli platini and levator

Figure 7. Stereoscopic side view of the intratemporal fossa.

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al. J Vasc Bras 2011, Vol. 11, Nº 1

Figure 8. Anatomo-radiologic correlation of the superﬁcial temporal artery. 1. frontal branch; 2. parietal branch. e arrow in the smaller ﬁgure indi-

cates the maxillary artery.

veli palatine muscles and to reach the foramen ovale,

which was observed in two cadavers. The mandibular

artery enters the mandibular foramen through the me-

dial surface of the mandible to supply the mandible and

the teeth of the inferior dental arch

The second portion of the maxillary artery was lo-

cated superficially to the lateral pterygoid muscle in all

specimens. The anterior and posterior branches of the

deep temporal artery supply the temporalis muscle. The

masseter artery runs inside the mandibular incisure

to reach the masseter muscle

7,9

. The pterygoid artery

presents a variable number and supplies the pterygoid

muscle. The buccal artery runs parallel to the buccal

branch of the mandibular nerve and supplies the skin

and mucous membrane above the buccinator muscle

7,9

(Figures 9 and 10).

Figure 9. Side view of the left face with dissection of deeper tissues.

e masseter muscle was removed. e insertion of the temporalis

muscle tendon was inserted in the coronoid process of the mandible.

1. mentalis muscle; 2. depressor labii inferioris; 3. depressor anguli oris;

4. platysma muscle ﬁbers; 5. orbicularis oris muscle; 6. risorius muscle;

7. greater zygomatic muscle; 8. facial artery; 9. angle of the mandible;

10. retromandibular vein; 11. coronoid process; 12. condylar process; 13.

temporalis muscle tendon inserted in the coronoid process; 14. zygoma;

15. superﬁcial temporal artery; 16. perioral fat.

Figure 10. Side view of the left face with dissection of deeper tissues,

using the stereoscopic technique.

Microsurgical anatomy of the external carotid artery: a stereoscopic study - Isolan GR et al.J Vasc Bras 2011, Vol. 11, Nº 1

Discussion

e external carotid artery supplies most of the so tis-

sues of the head and neck, as well as the meninges, giving

o six branches before dividing into the supercial tempo-

ral artery and the maxillary artery.

Studies on the external carotid artery are extremely im-

portant, due to the anatomical structures found there. Poor

knowledge of this artery surgical anatomy may lead to in-

advertent injuries. At operation, two parameters are used to

identify the external carotid artery: it runs more anteriorly

than the internal carotid artery and gives o several branch-

es in the neck, while the internal carotid artery has none.

Carotid endarterectomy is the surgical procedure with

the highest number of co-operative studies demonstrat-

ing its eectiveness. e selection criteria for symptomatic

patients were determined particularly by the co-operative

study called NASCET (North-American Symptomatic

Carotid Endarterectomy Trial)

, according which the neu-

rologically stable patients with carotid stenosis of 70% or

above benet from the surgery in the services where the

morbimortality is below 6%. e higher the stenosis degree,

the higher the surgery benet. But, in patients with stenosis

between 50 and 69%, the surgery should be indicated only

in services where the morbimortality is below 2%

When exposing the cervical spine for cervical spine

discectomy through an anterior approach, aer opening the

supercial fascia and retracting laterally the sternocleido-

mastoid muscle, the pre-tracheal fascia was observed, which

involves the muscles from the lower portion of the hyoid

(of which the most important is the omohyoid muscle), the

vasculo-nervous bundle, the esophagus and trachea. is

bounded region is called the carotid triangle

12,13

e occipital artery is the main branch used for arterial

bypass in the posterior fossa and it is usually anastomosed

to the posterior inferior cerebellar artery (PICA).

e ascending pharyngeal artery is the main blood

supply to the paragangliomas of the jugular foramen and

other tumors located in it.

For reconstruction of the base of the skull aer resec-

tion for carcinoma, the facial artery is the main artery used

to supply the ap to be graed. In juvenile nasopharyngeal

angiobromas, the maxillary artery is the main artery to

be embolized. In some cases, the posterior auricular artery

supplies the glomic tumors of the jugular foramen, and it

may be embolized in the preoperative period or ligated dur-

ing the operation.

e supercial temporal artery is the main vessel that

can be anastomosed in the M4 branch of the middle cere-

bral artery, in the low-ow bypass

e brain processes the stereoscopic view by observing

an object captured from two dierent points (retina of each

eye), providing a notion of depth. e stereoscopic photo-

graphic documentation provides this notion of depth which,

otherwise, would not be conceived with conventional 2D

images. Currently, 3D images have been increasingly pro-

duced, not only for medical publications, but especially for

general media, which can be seen in 3D movies and ani-

mationsproducedinthelastyears.However,itshouldbe

noted that this technology is not new. Since the publication

of Bassett Stereoscopic Atlas

, originally published in 1961

and reedited in 1994, up to two recently published micro-

surgery atlas, one edited by Poletti and Ojemann in 1985

and one by Kraus and Bailey in 1994

15,16

, stereoscopic im-

ages have been presented.

Recently, surgical and anatomical stereoscopic vid-

eos have been used for pedagogical purposes in projec-

tors, computer displays and printed (anaglyphic) method.

Besides oering a better anatomical illustration and a

better 3D understanding, the use of stereoscopic images

can also enhance the individual’s familiarity with his/her

own three-dimensionality and promote the spatially re-

lated skills. e article of Ribas et al.

already highlighted

that the form is the primitive unit of perception and that

stereoscopic images have denitive advantage in the pro-

duction of illustrations. Virtual environments for surgery

planning and training, which are being developed through

telesurgical systems, will also require stereoscopic visual-

ization and the individual’s familiarity with the 3D con-

cepts and stereoscopy.

Conclusion

e study of the external carotid artery, under the per-

spective of microsurgical anatomy, provides a 3D view to

the surgeon, due to the fact that an anatomical region can

be studied in dierent angles and according to the surgical

position of the patients. e stereoscopic documentation

is useful, as it adds the sense of depth of the documented

anatomy. Studies of this type can be more didactical in the

teaching of anatomy.

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Correspondence

Gustavo Rassier Isolan

Hospital de Clínicas de Porto Alegre

Rua Ramiro Barcelos, 2.350

CEP 90035-903 – Porto Alegre (RS), Brazil

E-mail: [email protected]

Author´s contributions

Study conception and design: GRI

Data analysis and interpretation: GRI, ACMA, MRP

Data collection: GRI

Writing: GRI, MRP

Critical analysis: AHP, PHPA, JPM

Final approval*: GRI, AHP, PHPA, SPM, MRP, ACMA

Overall responsibility: GRI*All authors have read and approved the ﬁnal version

submitted to J Vasc Bras.

All ﬁgures are available in color at: http://www.jvascbr.com.br/

Figures 6 and 10 need 3D glasses.