Ebook Requisites in dermatology - Dermatologic surgery: Part 1

Requisites in

DERMATOLOGY

Dermatologic
Surgery
Edited by

Allison T Vidimos,
RPh, MD, FAAD, FACMS

Chair, Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH, USA

Christie T Ammirati,
MD, FAAD, FACMS
Associate Professor,
Department of Dermatology
Penn State Milton S. Hershey Medical Center
Hershey, PA, USA

Christine Poblete-Lopez,
MD, FAAD, FACMS

Associate Staff,
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH, USA Series editor

DIRK M

ELSTON

Edinburgh London New York Oxford Philadelphia St Louis Sydney Toronto 2009


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First published 2009
ISBN: 978-0-7020-3049-9
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Printed in China


Acknowledgments
We would like to thank our mentors and teachers
who have taught us the art and science of
dermatologic surgery, our residents, fellows and
medical students who have given us the privilege
and pleasure of teaching them, and our patients
who put their trust in us and challenge us to be

better physicians every day. Special thanks go
to the the art and photography departments at
Cleveland Clinic, especially Joe Pangrace, Bill
Garriott, Beth Halasz, and our dermatology
department photographer, Flora Williams.

Dermatologic surgery dedications
This text is dedicated to my parents Al and
Audrey Vidimos, my brothers Scott, David and
Dan, my husband Todd Stultz, and daughters
Katherine and Kristen for their love, support,
encouragement, and inspiration.
Allison T Vidimos
This text is dedicated to my children Emma and
Nicholas and my parents Bob and Bee Travelute,

who inspired me to always reach higher, and to
my husband Chris, who held the ladder so I could
climb.
Christie T Ammirati

This text is dedicated to my husband, Seevee,
who has given me unconditional love and the
support to pursue what I truly enjoy, most evident
in this endeavor; to my children, Veto, Samee,
and Neo, who are the source of my strength
and inspiration; to my parents, who taught me
the value of education; to all my mentors, from
whom I learned the art of surgical technique; and
to all the residents and fellows to whom I’ve tried
to teach the importance of this art.
Christine Poblete-Lopez


Contributors

Erin J. Allen, md
Providence Dermatologic Surgery
Portland, OR
Christie T. Ammirati, md
Associate Professor of Dermatology
Department of Dermatology
Penn State Milton S. Hershey Medical Center
Hershey, PA
Philip L. Bailin, md
Program Director, Dermatologic Surgery

and Cutaneous Oncology
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH
Ashish C. Bhatia, md
Department of Dermatology and
Dermatologic Surgery
DuPage Medical Group,
Naperville, IL
Assistant Professor of Clinical Dermatology
Department of Dermatology
Northwestern University – Feinberg School
of Medicine
Chicago, IL
Elizabeth Magill Billingsley, md
Associate Professor of Dermatology
Department of Dermatology
Penn State Milton S. Hershey Medical Center
Hershey, PA
Lisa B. Campbell, md
Chief of Dermatology and Dermatologic
Surgery
Geisinger Health System Western Region
Geisinger Medical Group
State College, PA
T. Minsue Chen, md
Fellow, Mohs Research in Advanced
Dermatologic Surgery Education
Mohs and Dermasurgery Unit
Department of Dermatology

University of Texas, M. D. Anderson Cancer
Center
Houston, TX

Theresa Dressler Conologue, do
Director, Cosmetic Dermatology Service
Geisinger Medical Center
Danville, PA
Daihung Vu do, md
Instructor in Dermatology
Associate Director of Dermatologic Surgery
Department of Dermatology
Beth Israel Deaconess Medical Center
Boston, MA
John Ebner, do
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH
Gregory J. Fulchiero Jr, md, MSBioEng
Dermatologic Surgery and Cutaneous
Oncology
Department of Dermatology
UT Southwestern Medical Center
Dallas, TX
Christopher Charles Gasbarre, DO
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH
Lisa M. Grandinetti, md
Department of Dermatology

Cleveland Clinic Foundation
Cleveland, OH
Joseph F. Greco, md
Clinical Instructor
UCLA Division of Dermatology
Department of Medicine
David Geffen School of Medicine at UCLA
Los Angeles, CA


viii

Contributors

Christine M. Hayes, md
Associate Professor of Dermatology
Department of Dermatology
Boston University School of Medicine
Boston, MA

Christine Poblete-Lopez, md
Associate Program Director
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH

Christopher Riddell Jones, md
Department of Dermatology
Penn State Milton S. Hershey Medical Center
Hershey, PA

Matthew R. Ricks, md
LtCol, USAF, MC, SFS
Chief of Mohs Surgery
Wilford Hall Medical Center
Lackland AFB, TX

Ken K. Lee, md
Director of Dermatologic and Laser Surgery
Associate Professor of Dermatology, Surgery,
Otolarynogology – Head and Neck Surgery
Oregon Health and Science University
Portland, OR

Christopher B. Skvarka, md
Department of Dermatology
Hahnemann Hospital
Drexel University College of Medicine
Philadelphia, PA

Victor J. Marks, md
Department of Dermatology
Geisinger Medical Center
Danville, PA

Aashish Taneja, md
Department of Dermatology
Wayne State University
Dearborn, MI

Edward V. Maytin, md, PhD
Staff, Dermatology
Cleveland Clinic Foundation
Assistant Professor of Molecular Medicine
Cleveland Clinic Lerner College of Medicine
of Case Western Reserve University
Cleveland, OH

Leonid Benjamin Trost, md
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH

Susan Teri McGillis, md
Director, Dermasurgery Center
Lancaster, PA
Jon G. Meine, md
Staff, Department of Dermatology, Section
of Dermatologic Surgery and Cutaneous
Oncology
Cleveland Clinic Foundation
Cleveland, OH
Allison Jo Moosally, md
Clinical Associate Staff
Department of Dermatology
Cleveland Clinic Foundation
Cleveland, OH
Tri H. Nguyen, md
Director of Mohs/Dermatologic Surgery
Associate Professor

Mohs and Dermasurgery Unit
Department of Dermatology
University of Texas, M. D. Anderson Cancer
Center
Houston, TX

Allison T. Vidimos, RPh, md
Chair, Dermatology
Cleveland Clinic Foundation
Cleveland, OH
Paula S. Vogel, md
Col (Ret), USA, MC
Mohs Surgeon
Dermatology Associates
San Antonio, TX
Rungsima Wanitphakdeedecha, md
Department of Dermatology
Faculty of Medicine Siriraj Hospital
Mahidol University
Bangkok, Thailand
Andrea Willey, md
Assistant Clinical Professor
Department of Dermatology
University of California, Davis
Davis, CA
Brittany Wilson, md
Department of Dermatology
Oregon Health and Science University
Portland, OR

Contributors

Oliver J. Wisco, do
Maj, USAF, MC, FS
Department of Dermatology
Wilford Hall Medical Center
Lackland AFB, TX
Justin G. Woodhouse, md
University Dermatologists, Inc.
South Euclid, OH

Summer R. Youker, md
Assistant Professor of Dermatology
Saint Louis University
St Louis, MO

ix


Also in the series
Requisites in

Dermatology
Series Editor: Dirk M Elston

Dermatopathology

Dirk M Elston and Tammie Ferringer

Cosmetic Dermatology
Murad Alam, Hayes B Gladstone,
and Rebecca C Tung

Pediatric Dermatology
Howard B Pride, Albert C Yan,
and Andrea L Zaenglein

Dermatologic Surgery

Allison T Vidimos, Christie T Ammirati,
and Christine Poblete-Lopez

General Dermatology

Kathryn Schwarzenberger, Andrew E Werchniak,
and Christine J Ko


Series foreword
The Requisites in Dermatology series of textbooks
is designed around the principle that learning
and retention are best accomplished when
the forest is clearly delineated from the trees.
Topics are presented with an emphasis on the
key points essential for residents and practicing
clinicians. Each text is designed to stand alone as
a reference or to be used as part of an integrated
teaching curriculum. Many gifted physicians

have contributed their time and energy to create
the sort of texts we wish we had had during our
own training and each of the texts in the series
is accompanied by an innovative on-line module.
Each on-line module is designed to complement
the text, providing lecture material not possible
in print format, including video and lectures with
voice-over. These books have been a labor of love
for all involved. We hope you enjoy them.

Series dedication
This series of textbooks is dedicated to my wife
Kathy and my children, Carly and Nate. Thank
you for your love, support and inspiration. It is
also dedicated to the residents and fellows it has
been my privilege to teach and to the patients
who have taught me so much.
Dirk M Elston


Volume preface
This text is designed to cover the essentials of
dermatologic surgery in a style that is straight
forward and easily understood. Each topic is
presented as a concise, yet thorough, review,
and each chapter is paired with an on-line

lecture. In this manner, the text acts as an over­
view for students learning the surgical aspects
of dermatology, a focused study guide for

dermatology residents, and a ready reference for
those in practice.


Acknowledgments
We would like to thank our mentors and teachers
who have taught us the art and science of
dermatologic surgery, our residents, fellows and
medical students who have given us the privilege
and pleasure of teaching them, and our patients
who put their trust in us and challenge us to be

better physicians every day. Special thanks go
to the the art and photography departments at
Cleveland Clinic, especially Joe Pangrace, Bill
Garriott, Beth Halasz, and our dermatology
department photographer, Flora Williams.

Dermatologic surgery dedications
This text is dedicated to my parents Al and
Audrey Vidimos, my brothers Scott, David and
Dan, my husband Todd Stultz, and daughters
Katherine and Kristen for their love, support,
encouragement, and inspiration.
Allison T Vidimos
This text is dedicated to my children Emma and
Nicholas and my parents Bob and Bee Travelute,
who inspired me to always reach higher, and to
my husband Chris, who held the ladder so I could
climb.

Christie T Ammirati

This text is dedicated to my husband, Seevee,
who has given me unconditional love and the
support to pursue what I truly enjoy, most evident
in this endeavor; to my children, Veto, Samee,
and Neo, who are the source of my strength
and inspiration; to my parents, who taught me
the value of education; to all my mentors, from
whom I learned the art of surgical technique; and
to all the residents and fellows to whom I’ve tried
to teach the importance of this art.
Christine Poblete-Lopez


Joseph F. Greco and Christopher B. Skvarka

The essentials of dermatologic surgery must be
founded on a fundamental and thorough under­
standing of the head and neck anatomy.This ­chapter
begins with an outline of important topographic
landmarks and cosmetic units before focusing on
the musculature, nerve anatomy, vasculature, and
lymphatics of the head and neck. Special anato­
mic structures and regions such as the parotid
gland and scalp are addressed as well. Emphasis
has been placed on the boundaries of anatomic
regions and danger zones as well as the spacial
relationships among clinically relevent structures.

Topographical landmarks
Key Points
•The bony and muscular landmarks of the head
and neck aid in locating underlying structures.

•The supraorbital, infraorbital, and mental
foramina lie on the midpupillary line.

•The masseter muscle aids in locating the facial
artery and Stenson’s duct (parotid duct).

• The sternocleidomastoid muscle divides the neck
into anterior2 and posterior triangles.

The important topographical landmarks of the
head and neck are formed primarily by underlying
bones and musculature, but superficial accepted
divisions are also made. These landmarks and
divisions are important cosmetically and are used
in communication by the cutaneous surgeon.
The scalp is divided into four areas – frontal,
parietal, temporal, and occipital. The frontal scalp
extends from the forehead to the vertex and is
bordered by the parietal and temporal regions.
The occipital scalp is located at the inferior por­
tion of the scalp, and overlies the occipital bone.
The forehead meets the frontal scalp and extends
down to the eyebrows and glabella. The glabella
lies between the eyebrows superior to the nasal
root. Vertical furrows (glabellar lines) are accen­

tuated over this region when frowning.
The frontal, maxillary, zygomatic, temporal,
and mandibular bones all form prominent bony
surface markers – the orbital rims, zygomatic

1

Chapter

Surgical anatomy of the
head and neck

Table 1-1  The orbital rim

Border

Bones

Superior

Frontal bone

Lateral

Frontal process of zygomatic bone

Inferior

Zygomatic bone laterally and maxillary bone
medially

Medial

Frontal bone superiorly and maxilla inferiorly

arch, mastoid process, and mental protuberance.
The orbital rim is formed by contributions from
the frontal, zygomatic, and maxillary bones (­Table
1-�
1). Of note, the medial canthal ligaments are
easily palpated at the medial rim.
Immediately above the superior orbital rim
lies the first of the three major foramina that can
be found along a vertical, midpupillary line imag­
ined approximately 2.5 cm lateral to the midline
(Fig. 1-1). The supraorbital, along with the
­infraorbital and mental foramina will be discussed
further in the sensory innervation of the head and
neck section.
The prominence of the cheek or “cheekbone” is
formed by the malar eminence of the ­zygoma­tic
bone. The buccal fat pad fills the area beneath
this eminence and gives fullness to the cheek. The
zygomatic arch extends from the malar eminence
towards the external acoustic meatus and is formed
by the temporal process of the zygomatic bone
and the zygomatic process of the temporal bone.
The zygomatic arch also divides the temporal fossa
superiorly from the infratemporal fossa inferiorly.
The temple is a well defined danger zone where

the temporal branch of the facial nerve and the
superficial temporal artery and vein lie vulnerable
to injury (Table 1-�
2). The danger zones and areas
of susceptibility to injury are characterized later
in this chapter.
The auricle is the entire visible portion of the
external ear with many named processes (Fig. 1-2).
The rim of the auricle is known as the helix, which
runs with a paired prominence, the anti­helix. The
antihelix runs anterior to the helix and divides




Dermatologic Surgery

Parietal bone

Frontal bone

Midpupillary line

Supraorbital foramen
2.5cm

Temporal bone

Nasal bone

Infraorbital foramen
Mastoid process
Zygomatic arch

Maxillary bone

Ramus of mandible
Angle of mandible
Body of mandible
Mental foramen
Figure 1-1  Bony landmarks of the skull and foramina

into two crura. Between these crura, the named
triangular fossa appears. The curved depression
between the helix and antihelix is referred to as
the scapha. Inferior to the antihelix lies a deep
cavity known as the concha. Anterior to the con­
cha, the tragus arises as an eminence in front of
the external acoustic meatus. ­Opposite from the
tragus (separated by the intertragic notch) is a
small tubercle called the antitragus.
Behind the ear lies the mastoid process of the
temporal bone. It is a bony prominence that, after
adolescence, protects the facial nerve as it exits
the stylomastoid foramen.  Anterior to the ear lies
the condyle of the mandibular ramus, which can
be palpated as the mouth opens and closes. The
angle of the jaw and prominence of the chin are
formed by the mandibular angle and mental pro­
tuberance, respectively.

The masseter muscle attaches to the ­zygomatic
arch and inserts on the ramus of the mandible.
It can be palpated most easily while the teeth

Table 1-2  Borders of the temple

Border
Inferior

Zygomatic arch

Anterior

Tail of the eyebrow

Superior

Coronal suture line

Posterior

Temporal hairline

are clenched. The facial artery may be found and
palpated near the antero-inferior border of the
masseter.
The nasal bones, alar cartilages, and anterior
nasal spine of the maxilla form the palpable bor­
ders of the nose. The nasal bones form the supe­
rior root of the nose and the anterior nasal spine

can be palpated at the root of the columella.
The labial area is bordered by the nose, medial
cheek, and mental chin. This area is separated from
the cheek by the melolabial crease. The upper lip


ah
at
atn
c
cav
cym
ea
h

antihelix
antitragus
auriculotemporal nerve
conchal bowl
cavum of conchal bowl
cymba of conchal bowl
external auditory meatus
helix

hr
in
l
sf
sta
stv

tf
tr

Chapter

Surgical anatomy of the head and neck

1

helical root/crus
intertragic notch
lobule
scaphoid fossa
superficial temporal artery
superficial temporal vein
triangular fossa
tragus

Figure 1-2  Anatomy of the ear, superficial temporal artery, and auriculotemporal nerve

is divided in half by the philtrum. The philtrum is
a central linear depression bordered by two verti­
cal columns extending from the columella to the
vermillion border of the upper lip. At this inferior
border, the columns help to create a contoured
double curve, resembling Cupid’s bow.
Continuing inferiorly, the most important
­superficial landmark of the neck is the sternoclei­
domastoid muscle. When contracted, it is easily
palpated. See Table 1-�

3 for a discussion of the

sternocleidomastoid muscle. This muscle divides
the neck into anterior and posterior triangles (see
Table 1-�
4 for information on the anterior ­triangle
and Table 1-15 for the posterior triangle). The
­anterior triangle can be subdivided into the muscu­
lar, carotid, digastric, and submental triangles.
Of note, the spinal accessory nerve is suscep­
tible to injury in the posterior triangle. Injury
­results in paralysis of the sternocleidomastoid and
trapezius muscles.






Dermatologic Surgery
Table 1-3  The sternocleidomastoid muscle

Table 1-4  The anterior triangle

Origin

Boundary

Two heads – medial head attaches to the
sternum; lateral head attaches to the medial

third of the clavicle

Insertion

Mastoid process of the temporal bone and
lateral portion of the superior nuchal line

Innervation

Accessory nerve (cranial nerve XI)

Action

Acting alone, a single sternocleidomastoid
muscle turns the head towards the ipsilateral
shoulder in an upward glance; in tandem, both
sternocleidomastoid muscles draw the head
forward

Comments

The two originating heads of each
sternocleidomastoid muscle form a depression
referred to as the lesser supraclavicular fossa;
torticollis is due to the permanent contracture
of the sternocleidomastoid

Parotid gland and duct
Key Points
•The parotid glands are the largest paired salivary

glands.

•The facial nerve pierces the parotid gland soon
after leaving the stylomastoid foramen.

• The parotid duct may be palpated as it courses
over the masseter muscle.

The parotid gland is an anatomic landmark
deserving of special consideration. It is a ­triangularshaped salivary gland nestled anterior to the auri­
cle within the borders of the zygomatic arch and
mandible (Fig. 1-�
3, Table 1-�
5). It is anchored into
place by a fibrous fascial capsule contiguous with
the deep facia of the neck. The substance of the
gland houses and protects the facial nerve as it
branches into a superior temporofacial and infe­
rior cervicofacial division. The five well known
branches of the facial nerve originate from these
divisions prior to exiting the different poles of the
parotid gland (Table 1-�
6).
The parotid duct emerges from the gland at
its upper anterior pole and courses over the mas­
seter muscle and buccal fatpad (Fig. 1-�
4). Here
it turns medially to pierce the buccinator muscle
and ­ enters the oral mucosa opposite the second
upper molar (Fig. 1-�

5). The duct runs approxi­
mately one fingerbreadth inferior to the zygomatic
arch, between the transverse facial artery and
buccal branch of the facial nerve. With the jaw
clenched, the parotid duct may be palpated as a
firm cord along the middle third of a line drawn
from the earlobe to a point between the oral com­
missure and the nasal ala as it runs atop the mas­
seter. The duct is most vulnerable in this ­location

Anterior

Median line of neck

Posterior

Anterior border of sternocleidomastoid
muscle

Superior (base)

Inferior border of mandible

Roof

Skin, SMAS, platysma, and deep fascia
of neck

Floor

Inferior and middle pharyngeal constric­
tors; thyrohyoid and hyoglossus muscles
(carotid triangle); mylo­hyoid and
hyoglossus muscles (digastric triangle),
mylohyoid muscle (submental triangle)

during surgical procedures. ­Transection will result
in extravasation of a clear watery fluid. If left
­unrepaired, an external fistula may develop.
Thin watery saliva and thicker mucous of the
parotid gland mediated by sympathetic and para­
sympathetic fibers respectively. Cutaneous sen­
sory innervation over the parotid gland is carried
by the auriculotemporal nerve. Vascular supply
and lymphatic drainage of the parotid area are
des­cribed elsewhere in this chapter.

Contour lines and cosmetic
units
Key Points
•Contour lines separate the face into anatomic
subunits.

•Regional variablility in skin structure impacts the
dermatologic surgeon’s choice of repair.

• Free margins are a type of contour line.

Contour lines are the natural lines of demarcation
that divide the face into several cosmetic units,

such as the forehead and nose (Table 1-�
7). Gen­
erally speaking, the skin texture and color is con­
sistent within each cosmetic unit and may vary
considerably among them. This is due in part to
the differences in the density of sebaceous glands,
terminal hair follicles, thickness and elasticity of
the skin. The highly thick and sebaceous skin of
the nose, for example, lies in stark contrast to the
neighboring thin and highly lax skin of the eyelid.
Defects in one cosmetic unit are therefore best
repaired with skin of that same cosmetic unit. The
dermatologic surgeon must consider this regional
variability during reconstructive surgery. Surgical
incisions may be placed so that the final scar lies
along or parallel to contour lines. Incisions that
violate this principle by crossing the demarca­
tion lines may distort anatomic units and result in
highly perceptible scarring.


bfp
fa
fv
ma
orb oc

buccal fat pad
facial artery
facial vein

masseter muscle
orbicularis oculi

orb or
pd
scm
sta
tfa
zm

Chapter

Surgical anatomy of the head and neck

1

orbicularis oris
parotid duct
sternocleidomastoid muscle
superficial temporal artery
transverse facial arter
zygomaticus major

Figure 1-3  Anatomy of the parotid gland and related structures

Table 1-5  Borders of the parotid gland

Superior

Posterior two thirds of zygomatic arch

Posterior

Posterior border of mandibular ramus

Inferior

Angle of mandible

Anterior

Highly variable

Floor

Posterior half of masseter

Roof

Integument, parotid fascia

Free margins are a unique type of anatomic
unit characterized by skin edges that are ­separated
from neighboring tissue by an open cavity. Exam­
ples include the lips, eyelids, helical rims, nasal
alae, and columella. Defects and repairs in close
proximity to free margins may have tension forces
that push or pull on the margin. Distortion may
result in both aesthetic and functional impairment

Table 1-6  Facial nerve branches and the parotid gland

Facial nerve branch

Exiting pole of the
parotid

Temporal (temporofacial division)

Superior

Zygomatic (temporofacial division)

Anterosuperior

Buccal (temporofacial division)

Anterior

Marginal mandibular
(cervicofacial division)

Anteroinferior

Cervical (cervicofacial division)

Inferior

such as eversion of the eyelid (ectropion) or lip
(eclabion).

Cosmetic units may be further divided into
subunits for anatomic classification. This permits
more precise localization of cutaneous neoplasms
especially in patients presenting with numerous
lesions.






Dermatologic Surgery

b
bfp
bz
fa
fv
orb oc

buccal branch (VII)
buccal fat pad
buccal/zygomatic nerve anastomoses
facial artery
facial vein
orbicularis oculi

pd
pg
t

tfa
z
zm

parotid duct
parotid gland
temporal branch (VII)
transverse facial artery
zygomatic branch (VII)
zygomaticus major

Figure 1-4  Anatomy of the parotid duct and facial nerve

The superficial
musculoaponeurotic system
(SMAS)
Key Points
• The fibromuscular layer is composed of the

muscles of facial expression and enveloping fascia.

•Muscular contraction is transmitted evenly to the
skin and adjacent muscles via this system.

•The SMAS permits complex facial movements
and contributes to the symmetry of the face.

•It provides an anatomic plane for dissection and
protection to neurovascular structures.

• It acts a barrier to infection.

The superficial musculoaponeurotic system
(SMAS) lies just deep to the subcutaneous fat and
contains two layers of fascia that split to envelop
the muscles of facial expression. The breadth of
the SMAS is described in Table 1-�
8. In addition
to these musculofascial connections, the SMAS
bonds to the skin via fibrous strands. Collectively,
this system augments and harmonizes facial
movements, while acting as a screen to prevent
the spread of infection from superficial to deep
regions (Fig. 1-�
6).
Knowledge of the SMAS aids the cutaneous
surgeon in predicting the location of major neuro­
vascular structures. Arteries and sensory nerves of
the face are found within the subcutaneous fat or


an
b
bfp
dao
fa

fv
m
pd

pg

facial nerve anastomoses
buccinator muscle
buccal fat pad
depressor anguli oris
facial artery

Chapter

Surgical anatomy of the head and neck

1

facial vein
masseter muscle
parotid duct
parotid gland

* parotid duct piercing buccinator muscle
* marginal mandibular nerve traveling with facial artery
Figure 1-5  Parotid duct as it pierces the buccinator muscle

Table 1-7  Cosmetic units and contour lines
of the face

Contour line

Cosmetic unit

  Nasolabial fold

�

  Nasofacial sulcus

�

  Mentolabial crease

�

  Preauricular sulcus

�

  Eyelid margins

�

  Philtral columns/crest

�

  Alar contours

�

�
�

�
�
�
�
�

  Vermillion border

�

  Eyebrows

�

  Hairline

�

  Forehead
  Nose
  Cheek
  Eye
  Lip
  Chin
  Ear

at the SMAS–subcutaneous fat junction. All mo­
tor nerves course below the SMAS. A sub-SMAS
dissecting plane is attractive owing to its ­relatively
avascular nature. However, the risk to the motor

nerves precludes use of the sub-SMAS plane in
most locations. The subcutaneous fat superficial
to the SMAS is therefore the ideal dissecting
plane. An exception occurs over the pre-parotid
cheek where the motor fibers of the facial nerve
lie protected within the substance of the parotid
gland.
Of note, the temporal branch of the facial
nerve lies just deep to the thin superficial tem­
poral ­fascia on the medial temple. On the lateral
temple, the auriculotemporal nerve and ­superficial
temporal vessels are located in the subcutaneous
fat above the superficial temporal fascia.






Dermatologic Surgery
Table 1-8  SMAS relationships

Skin tension lines of the face
(STLs)

Region

SMAS attachment site

Posterior

(occiput)

Inserts onto the mastoid process and fascia
of sternocleidomastoid muscle; envelops
occipitalis

Key Points

Superior
(scalp)

Forms the galea aponeurotica to unite the
occipitofrontalis muscle; lacks muscle fibers

• Dynamic and relaxed STLs lie perpendicular to

Forehead

Envelops frontalis muscle

• Lines become more visible and deeper with age

Temporal
scalp

Continuous with the superficial temporal fascia

• Knowledge of the skin tension lines is required

Zygomatic

arch

SMAS is discontinuous above and below
this insertion point; the actions of the upper
and lower muscles of facial expression are
functionally separated here

Cheek

Deep leaflet of the SMAS fuses with the parotid
and masseteric fascia; envelops muscles of
facial expression

Anterior
(neck)

Continuous with the superficial cervical fascia;
envelops platysma

Midfacial
region

Devoid in areas; not well delineated

• Skin tension lines are the distinctive furrowed or
wrinkled lines on the face.

the action of underlying muscle fibers.

and sun damage.

for successful cutaneous surgery and proper use
of cosmetic injectables.

Tension, created by the intermittent contraction
of the muscles of facial expression, is transmit­
ted by fibrous strands from the SMAS to the skin.
The elasticity of the skin with youth opposes this
tension and maintains a smooth appearance. With
age, the elastic fibers decrease in their ability to
resist tension, and collagen fibers elongate, decrease
in size, and become cross-linked. With damaged
collagen and elastin, linear wrinkles form along
the attachments of the SMAS to the skin.

*

* SMAS fibers connecting the underlying temporalis muscle to the skin
Figure 1-6  Superficial musculoaponeurotic system (SMAS)


Chapter

Surgical anatomy of the head and neck

1

Figure 1-7  Skin tension lines

Generally these wrinkles, termed skin tension

lines (STLs), run perpendicular to the underlying
muscle fibers (Fig. 1-�
7). For example, the STLs of
the forehead are horizontal because the frontalis
muscle contracts vertically. The skin tension lines
of the lateral periocular skin (crow’s feet) radiate
away from the lateral canthus, as the fibers of the
orbicularis oculi circumferentially wrap from the
superior to inferior eyelid. The horizontal wrinkles
of the upper eyelid, which at first seem to contra­
dict this principle, lie perpendicular to the axis of
the underlying levator palpebrae superioris.
Surgical planning must include a thorough
knowledge of the STLs. The reconstruction of sur­
gical defects should be designed to minimize per­
ceptible scarring. One such way is to align the long
axis of a repair within or parallel to the STLs. This
places the scar under the least amount of tension,
allowing the scar to fall within a natural wrinkle.
Wounds close more easily in this orientation, as
the skin is approximately three times more disten­
sible perpendicular to the STLs than parallel.
In elderly patients with severe sun damage,
the relaxed STLs will be obvious to any observer.
However, certain techniques may be utilized to
accentuate these lines where the static wrinkles

may not be so noticeable. Furrows can be accen­
tuated by asking patients to perform exaggerated
facial expressions, such as smiling, frowning,

puckering lips, or whistling. Active manipulation
of the skin by a gentle pinch or massage may also
reproduce the natural folds and tension lines.
STLs may be softened or eliminated by cos­
metic injectable treatments. Injectable botulinum
toxin targets the dynamic STLs and moderately
fine relaxed STLs by blunting the actions of
the underlying musculature. However, deeper
­relaxed STLs, accentuated by the gravitational
pull of sun-damaged skin, are better treated by
injectable fillers, which replace volume loss.

The facial nerve and muscles
of facial expression
Key Points
•The muscles of facial expression develop from
the second embryonic arch.

•They contribute to the relaxed skin tension lines
of the face.

• They are innervated by the seventh cranial nerve –
the facial nerve.




10

Dermatologic Surgery

Temporal branches

Zygomatic arch
Superficial temporal artery

Zygomatic branch

Stylomastoid foramen

Facial nerve (CN-VII):
main trunk

Parotid duct
Buccal branches

Temporofacial division of VII
Cervicofacial division of VII

Facial artery
Masseter muscle
Marginal mandibular branches

Parotid gland
Cervical branch

Figure 1-8  Illustration of the facial nerve

The facial nerve, or cranial nerve VII, exits the
skull at the stylomastoid foramen and proceeds

to innervate the muscles of facial expression
(Fig. 1-�
8). Immediately after exiting the foramen,
the posterior auricular branch breaks off the main
trunk to innervate the occipitalis and ­postauricular
muscles. The remainder of the nerve pierces the
parotid gland and departs as five branches –
temporal, zygomatic, buccal, marginal mandi­
bular, and cervical (Fig. 1-�
9). Each branch of the
nerve is discussed separately. Table 1-�
9 highlights
the muscles innervated by each branch.
During surgical procedures injury to a single
branch of the facial nerve is more likely to occur
than injury to the main trunk. Conflicting ­reports
exist on the most common branch injured, as

the temporal, buccal, and marginal mandibular
branches have all been implicated in different
series. Permanent injury to one of the branches
of the facial nerve is reported as 0.4–2.6%, with
equal rates for subcutaneous and sub-SMAS
­procedures.
The temporal branch is particularly vulnerable
to damage on the lateral face after exiting the
­superior pole of the parotid gland (Table 1-10, Fig.
1-10). This branch runs deep to the skin, subcu­
taneous tissue and a thin layer of fascia along its
course to the frontails and orbicularis oculi mus­

cles. To prevent damage to this nerve, the surgeon
should only dissect down to the superficial fat in
this area. Table 1-10 highlights other areas where
the facial nerve is susceptible to injury.


b
bz
c
fa

buccal branch
buccal/zygomatic anastomoses
cervical branch
facial artery

dotted line
dotted circle

mm
t
z

Chapter

Surgical anatomy of the head and neck

1

marginal mandibular branch

temporal branch
zygomatic branch

damaged nerves anterior to it likely result in full recovery while
damaged nerves posterior to it likely result in permanent paralysis
danger zone for fa and mm

Figure 1-9  Anatomy of the facial nerve

The zygomatic branch exits the anterosuperior
border of the parotid gland and divides into ­upper
and lower rami (see Figs 1-4 & 1-9). Branches of
the lower ramus lie on the parotid duct. Injury
to the zygomatic branch results in difficult clos­
ing the ipsilateral lower eyelid and can affect the
nasal muscles and lip ­elevators.
The buccal branch exits the anterior border of
the parotid gland before coursing anteriorly over
the masseter muscle and buccal fat pad. This
­division runs parallel to the parotid duct prior to
delivering extensive rami to the mid-facial region
(see Figs 1-4 & 1-9). Damage to this branch may
lead to the accumulation of food between the
teeth and buccal mucosa while chewing, as well
as drooling, impaired lip pursing, and impaired
smiling. Injury to the zygomatic or buccal branch­
es is often temporary because of the high degree
of anastamoses between the two branches. Some
70–90% of ­patients have these anastomoses.

The marginal mandibular branch exits the infe­
rior pole of the parotid gland and travels along the
lower angle of the mandible anterior to the facial
artery (see Fig. 1-�
9). Ramification occurs distally,
near the muscles of the lower lip. This renders the
nerve vulnerable in its more proximal subplatys­
mal location near the anterior insertion point of
the masseter muscle on the mandible. With injury
to this nerve, the lower lip becomes impaired in
its downward movement, which can lead to an
asymmetric smile.
The cervical branch of the facial nerve exits
the inferior pole of the parotid gland and ­descends
toward the submandibular triangle before ram­
ifying extensively to innervate the platysma (see
Fig. 1-�
9). Injury to this branch rarely causes
­noticeable damage.
The extensive anastomotic network of the
facial nerve, particularly via the zygomatic and
buccal branches, may be predicted by dropping

11


12

Dermatologic Surgery
Table 1-9  Muscles innervated by the facial nerve

Table 1-10  Areas of the facial nerve susceptible to injury

Branch of facial nerve

Muscle innervated
by branch

Branch of facial
nerve

Danger zone description

Temporal

Frontalis

Facial nerve
trunk as it exits
the stylomastoid
foramen

Behind the earlobe in children, the
facial nerve trunk is vulnerable to injury.
In adults, the trunk is protected by the
mastoid process

Auricular

Facial nerve in

the parotid gland

Vulnerable to injury if the procedure
breaches the fascia of the parotid gland

Orbicularis oculi (lower
portion)

Temporal branch 

Located between an imaginary line
drawn between the earlobe and the
lateral eyebrow and a second line drawn
between the earlobe and the most
superior forehead crease. It lies in its
most superficial position as it crosses
the zygomatic arch. The facial nerve
likely has multiple rami at this point

Buccal branch

Lying superficial to the masseter muscle,
but deep to SMAS, this section is
vulnerable at its branching points, 2 cm
anterior to its exit of the parotid gland
and under the modiolus (see below)

Marginal
mandibular

This branch lies just below the fascia of
the SMAS anterior to the facial vein and
artery as it crosses the inferior edge of
the mandible near the insertion point of
the masseter

Corrugator supercilii
Orbicularis oculi (upper
portion)
Zygomatic

Nasalis (alar portion)
Procerus
Buccinator
Buccal

Buccinator
Depressor septi nasi
Nasalis (transverse portion)
Zygomaticus major and
minor
Levator labii superioris
Levator anguli oris
Risorius
Orbicularis oris (upper
portion)

Marginal mandibular

Orbicularis oris (lower

portion)
Depressor anguli oris
Depressor labii inferioris
Mentalis

Cervical

Platysma

nerve (Fig. 1-15). See ­ Boxes 1-1 through 1-3 for
the other functions of the facial nerve.

Sensory innervation of the
head and neck
The trigeminal nerve

an imaginary vertical line down from the lat­
eral canthus. Branches anterior to this line have
­extensive anastomoses, and injured nerves in this
“safe zone” will likely recover. Damage posterior
to this line, however, often results in permanent
paralysis of the target musculature.
Table 1-11 discusses each muscle of facial
­expression separately. See Figures 1-11 through
1-13 for the muscular anatomy of the face. With
the exception of the buccinator, the muscles
of ­ facial expression receive motor innervation
from their deep surface and thus protect their
­terminal branches (Fig. 1-14). Of note, the ­levator
­palpebrae superioris muscle elevates the upper

­eyelid under the direction of the ­ oculomotor
nerve ­ (cranial nerve III) rather than the facial

Key Points
•The trigeminal nerve, cranial nerve V, is the
largest of the 12 cranial nerves.

•The three main branches are the ophthalmic (V1),
maxillary (V2), and mandibular (V3).

•The trigeminal nerve provides the primary
sensory innervation to the face.

•It also provides motor innervation to the muscles
of mastication.

• Effective anesthesia via nerve blocks can be placed
by the cutaneous surgeon with an understanding
of the anatomy of the trigeminal nerve.

The trigeminal nerve, the largest of the cranial
nerves, is the fundamental provider of sensory
­innervation to the face, supplying structures de­
rived from the first branchial arch. Three branches


Chapter

Surgical anatomy of the head and neck

1

The danger zone is predicted by drawing an imaginary line between the earlobe and the lateral
eyebrow and a second line drawn between the earlobe and the most superior forehead crease.
The temporal branch of the facial nerve is vulnerable to injury as it courses over the zygomatic
arch within this zone.
Figure 1-10  The facial nerve: danger zone
Table 1-11  The muscles of facial expression

Muscle

Contraction

Origin

Insertion

Comments

Frontalis

Raises eyebrows and
wrinkles forehead;
allows skin to slide
over scalp

Galea aponeurosis

Fibers intertwine with
procerus, orbicularis

oculi, and corrugator
supercilii muscles

Part of the epicranius;
the fibers of the
frontalis are vertically
oriented. The horizontal
forehead skin tension
lines are created by this
muscle. If denervated,
the eyebrow droops
and skin tension lines
relax on the damaged
side

Corrugator supercilii

Draws eyebrows
medially and downward

Nasal bone

Skin above middle
eyebrow

Creates the vertical
glabellar frown lines
with the medial portion
of the orbicularis
oculi and depressor

supercilii

Orbicularis oculi

Eyelid closure
and upper eyelid
depression; aids in tear
excretion

Medial canthal tendon
and nasal portion of
frontal bone

Eyelid skin and
surrounding
musculature; lateral
portion of orbicularis
oculi is uninterrupted at
the lateral canthus

Contraction forms folds
that radiate from the
lateral canthus (“crow’s
feet”)

13


14

Dermatologic Surgery
Table 1-11  The muscles of facial expression—cont’d

Muscle

Contraction

Origin

Insertion

Comments

Nasalis

Compresses and
widens nasal aperture
(“flares nostrils”) with
deep inspiration

Maxilla lateral to nasal
notch

Nasal aponeurosis

Major muscle of the
nose

Levator labii
superioris alaque nasi

Elevates ala and upper
lip

Superiorly at maxilla

Alar cartilage and
upper lip

Procerus

Draws down medial
angle of eyebrow and
produces horizontal
wrinkles over nasal
bridge

Nasal bones and
cartilage

Skin between eyebrows

Temporary paralysis
of this muscle helps
to reduce “bunny
lines”; continuous with
frontalis muscle

Buccinator

Compresses cheek
against teeth

Maxilla and mandible

Submucosa of cheek
and orbicularis oris

Muscular wall of cheek;
if denervated, food
accumulates between
teeth and cheek while
chewing. Pierced by
parotid duct as it enters
the mouth; receives
motor innervation from
its superficial surface

Zygomaticus major

Upper lip elevator;
draws angle of mouth
upward

Zygomatic bone

Upper lip, angle of
mouth

Important for smiling

and laughing

Zygomaticus minor

Upper lip elevator

Zygomatic bone

Orbicularis oris muscle

Deepens nasolabial
sulcus during sadness

Levator labii
superioris

Elevates and everts
upper lip

Maxilla and zygomatic
bone

Upper lip

Provides a protective
roof over the
infraorbital foramen

Levator anguli oris

Raises angle of mouth

Maxilla

Angle of mouth

Contributes to depth of
nasolabial furrow

Risorius

Draws corner of mouth
laterally

Zygomatic arch and
parotid fascia

Angle of mouth/
modiolus

Important for the smile

Orbicularis oris

Sphincter muscle
of lips for closing,
pursing, protruding, or
inflecting (prevents lip
protrusion)

Maxilla, mandible, and
modiolus (1 cm lateral
to corner of lips; fibers
from orbicularis oris,
lip elevators, and lip
depressors converge to
form a compact, mobile,
fibromuscular mass
called the modiolus)

Lips and vermillion
border

Modiolus contributes
to cheek dimples

Depressor anguli oris

Pulls angle of mouth
downward and laterally

Mandible

Angle of mouth

Depressor labii
inferioris

Draws lower lips
downward as to convey

impatience, and may
assist with eversion

Mandible and mental
foramen

Skin and mucosa of
lower lip

Contributes to
expression of irony,
sorrow, melancholy,
and doubt

Mentalis

Raises skin of chin
and everts lower lip
to express doubt or
to pout

Mandible

Skin of chin

A wide space between
the two mentalis
muscles can create a
chin dimple

Platysma

Depresses and wrinkles
skin of lower face and
neck

Mandible

Skin of neck and chest

Most superficial
muscle of neck;
overlies facial artery
and vein, as well as
marginal mandibular
and cervical branches
of facial nerve


Anterior auricular

Chapter

Surgical anatomy of the head and neck

1

Superior auricular

Frontal belly of

occipitofrontalis

Orbicularis oculi
Corrugator supercilii
Procerus
Nasalis
Levator labii
superioris
alaeque nasi
Levator labii
superioris
Zygomaticus minor
Occipital
belly of
occipitofrontalis

Zygomaticus major
Modiolus
Orbicularis oris
Depressor labii
inferioris
Mentalis

Posterior auricular

Depressor anguli oris
Risorius
Buccinator
Platysma

Figure 1-11  Muscles of facial expression

15