plastic surgery -

SECT

ION

IA

esth

etic

Sur

ger

y o

f th

e Fa

ce

6

Anat

omy

of th

e ag

ing

face

Bry

an M

end

els

on a

nd

Chin

-Ho W

ong

intr

aope

rati

ve m

ap f

or t

he s

urge

ons

to s

afel

y na

viga

te t

o th

e ar

ea o

f in

tere

st t

o co

rrec

t ag

ing

chan

ges.

Thi

s is

mos

t im

por-

tant

in a

dd

ress

ing

the

over

rid

ing

conc

ern,

bei

ng th

e co

urse

of

the

faci

al n

erve

bra

nche

s. A

n an

atom

ical

app

roac

h to

sur

gica

l re

juve

nati

on o

f th

e fa

ce p

rovi

des

the

way

to

obta

inin

g a

nat

ural

re

sult

tha

t is

last

ing

and

wit

h m

inim

al m

orbi

dit

y.

Regi

ons

of th

e fa

ceT

he t

rad

itio

nal

appr

oach

to

asse

ssin

g th

e fa

ce i

s to

con

sid

er

the

face

in

thir

ds

(upp

er,

mid

dle

, an

d l

ower

thi

rds)

.2 W

hile

us

eful

, th

is a

ppro

ach

limit

s co

ncep

tual

izat

ion,

as

it i

s no

t ba

sed

on

the

func

tion

of

the

face

. Fro

m a

fun

ctio

nal p

ersp

ec-

tive

, the

fac

e ha

s an

ant

erio

r as

pect

and

a l

ater

al a

spec

t. T

he

ante

rior

fac

e is

hig

hly

evol

ved

bey

ond

the

bas

ic s

urvi

val

need

s, s

peci

cal

ly, f

or c

omm

unic

atio

n an

d f

acia

l ex

pres

sion

. In

con

tras

t, th

e la

tera

l fa

ce p

red

omin

antl

y co

vers

the

str

uc-

ture

s of

mas

tica

tion

.3 A

ver

tica

l lin

e d

esce

ndin

g fr

om t

he

late

ral

orbi

tal

rim

is

the

appr

oxim

ate

div

isio

n be

twee

n th

e an

teri

or a

nd l

ater

al z

ones

of

the

face

. In

tern

ally

, a

seri

es o

f fa

cial

ret

aini

ng l

igam

ents

are

str

ateg

ical

ly l

ocat

ed a

long

thi

s lin

e to

dem

arca

te t

he a

nter

ior

from

the

lat

eral

fac

e (F

ig. 6

.1).

The

mim

etic

mus

cles

of

the

face

are

loca

ted

in t

he s

uper

cia

l fa

scia

of

the

ante

rior

fac

e, m

ostl

y ar

ound

the

eye

s an

d t

he

mou

th.

Thi

s hi

ghly

mob

ile a

rea

of t

he f

ace

is d

esig

ned

to

allo

w

ne m

ovem

ent

and

is

pron

e to

dev

elop

lax

ity

wit

h ag

ing.

In

cont

rast

, the

lat

eral

fac

e is

rel

ativ

ely

imm

obile

as

it

over

lies

the

stru

ctur

es to

do

wit

h m

asti

cati

on, t

he te

mpo

ralis

, m

asse

ter,

the

paro

tid

gla

nd a

nd i

ts d

uct,

all

loca

ted

dee

p to

th

e d

eep

fasc

ia. T

he o

nly

supe

rci

al m

uscl

e in

the

late

ral f

ace

is t

he p

laty

sma

in t

he lo

wer

thi

rd, w

hich

ext

end

s to

the

leve

l of

the

ora

l com

mis

sure

.Im

port

antl

y, t

he s

oft

tiss

ues

of t

he a

nter

ior

face

are

sub

di-

vid

ed in

to tw

o pa

rts;

that

whi

ch o

verl

ies

the

skel

eton

and

the

larg

er p

art

that

com

pris

es t

he h

ighl

y sp

ecia

lized

sph

inct

ers

over

lyin

g th

e bo

ny c

avit

ies.

4 Whe

re th

e so

ft ti

ssue

s ov

erlie

the

orbi

tal a

nd o

ral c

avit

ies

they

are

mod

ied

, as

ther

e is

no

dee

p

SY

NO

PS

IS

Agin

g of

the

face

is a

mul

tifac

toria

l pro

cess

that

can

be

expl

aine

d on

an

anat

omic

al b

asis

.

The

face

is c

onst

ruct

ed o

f ve

bas

ic la

yers

that

are

bou

nd to

geth

er

by a

sys

tem

of f

acia

l ret

aini

ng li

gam

ents

.

To fa

cilit

ate

the

mob

ility

need

ed fo

r fac

ial e

xpre

ssio

n in

depe

nden

t of

the

basi

c fu

nctio

ns o

f the

face

, par

ticul

arly

of m

astic

atio

n, a

se

ries

of s

oft t

issu

e sp

aces

are

inco

rpor

ated

into

the

arch

itect

ure

of th

e fa

ce.

This

arr

ange

men

t, m

ost c

lear

ly s

een

in th

e sc

alp,

als

o ex

ists

in

the

rest

of t

he fa

ce, a

lthou

gh w

ith s

igni

can

t com

pact

ion

and

mod

ica

tions

.

This

cha

pter

will

desc

ribe,

in d

etai

l, th

e v

e-la

yere

d co

nstru

ct o

f th

e fa

ce, i

nclu

ding

the

spac

es a

nd re

tain

ing

ligam

ents

, and

will

high

light

the

rele

vanc

e of

thes

e st

ruct

ures

in th

e ag

ing

face

.

In a

dditi

on, t

he p

rofo

und

impa

ct o

f agi

ng o

f the

faci

al s

kele

ton

shou

ld b

e ap

prec

iate

d.

Unde

rsta

ndin

g th

ese

prin

cipl

es w

ill he

lp n

ot o

nly

in u

nder

stan

ding

th

e ag

ing

proc

ess

but a

lso

in d

esig

ning

pro

cedu

res

that

are

logi

cal

and

effe

ctiv

e in

reve

rsin

g th

e st

igm

ata

of th

e ag

ing

face

.

Intr

oduc

tion

Faci

al a

ging

is a

com

plex

pro

cess

that

is th

e cu

mul

ativ

e ef

fect

of

sim

ulta

neou

s ch

ange

s of

the

man

y co

mpo

nent

s of

the

fac

e as

wel

l as

the

inte

ract

ion

of th

ese

com

pone

nts

wit

h ea

ch o

ther

. A

n un

der

stan

din

g of

the

ana

tom

ical

cha

nges

ass

ocia

ted

wit

h ag

ing

is r

equi

red

in

ord

er t

o d

esig

n ef

fect

ive

proc

edur

es t

o re

juve

nate

var

ious

asp

ects

of

the

agin

g fa

ce. F

und

amen

tal t

o un

der

stan

din

g th

ese

chan

ges

is a

rm

gro

und

ing

in th

e pr

in-

cipl

es o

n w

hich

the

fac

ial

soft

tis

sue

laye

rs a

re c

onst

ruct

ed.1

Thi

s is

im

port

ant

beca

use

the

path

ogen

esis

of

faci

al a

ging

is

expl

aine

d o

n an

ana

tom

ical

bas

is, p

arti

cula

rly

the

vari

atio

ns

in t

he o

nset

and

out

com

e of

agi

ng s

een

in d

iffe

rent

ind

i-vi

dua

ls. U

nder

stan

din

g th

e pr

inci

ples

on

whi

ch th

e fa

cial

sof

t ti

ssue

s ar

e co

nstr

ucte

d is

the

basi

s fo

r an

acc

urat

e an

d r

elia

ble

20

13,

Else

vier

Inc.

All

right

s re

serv

ed.

79Su

rgic

al a

nato

my

of th

e fa

ce, S

MAS

, fac

ial s

pace

s an

d re

tain

ing

ligam

ents

fasc

ial l

ayer

for

sup

port

. Acc

ord

ingl

y, s

uppo

rt d

oes

not c

ome

from

wit

hin

the

cavi

ty b

enea

th, b

ut f

rom

the

rim

of

the

cavi

-ti

es.

The

tra

nsit

ions

bet

wee

n th

ese

area

s, w

hile

not

see

n in

yo

uth,

bec

ome

incr

easi

ngly

evi

den

t w

ith

agin

g.

Surg

ical

ana

tom

y of

the

face

, SM

AS,

faci

al s

pace

s an

d re

tain

ing

ligam

ents

The

sof

t ti

ssue

of

the

face

is

arra

nged

con

cent

rica

lly i

nto

the

ve

basi

c la

yers

5,6 :

(1)

skin

; (2

) su

bcut

aneo

us;

(3)

mus

culo

-ap

oneu

roti

c la

yer;

(4)

are

ola

tiss

ue; a

nd (

5) d

eep

fasc

ia. T

his

ve-

laye

red

arr

ange

men

t is

mos

t cle

arly

see

n in

the

scal

p an

d

fore

head

as

a re

sult

of e

volu

tion

ary

expa

nsio

n of

the

und

erly

-in

g cr

ania

l vau

lt n

eces

sary

to a

ccom

mod

ate

the

high

ly d

evel

-op

ed f

ront

al l

obe

in h

uman

s. A

ccor

din

gly,

the

sca

lp i

s an

ex

celle

nt p

lace

to s

tud

y th

e pr

inci

ples

of t

he la

yere

d a

nato

my

(Fig

. 6.

2).

Lay

er 4

(th

e lo

ose

areo

lar

tiss

ue)

is t

he l

ayer

tha

t al

low

s th

e su

per

cial

fas

cia

(de

ned

as

the

com

posi

te

ap o

f la

yers

1 th

roug

h 3)

to g

lide

over

the

dee

p fa

scia

(lay

er 5

). T

he

sim

pli

ed a

nato

my

over

the

sca

lp g

ives

the

bas

ic p

roto

type

of

lay

er 4

. T

here

are

not

any

str

uctu

res

cros

sing

thi

s pl

ane,

w

hich

is

esse

ntia

lly a

n av

ascu

lar

pote

ntia

l sp

ace.

At

the

boun

dar

ies

of t

he s

calp

alo

ng t

he s

uper

ior

tem

pora

l lin

e an

d

acro

ss t

he s

upra

orbi

tal

rim

, th

e sc

alp

and

the

for

ehea

d a

re

rm

ly a

ncho

red

by

ligam

ento

us a

ttac

hmen

ts. V

ital

str

uctu

res,

th

e ne

rves

and

ves

sels

are

alw

ays

loca

ted

in

clos

e pr

oxim

ity

to t

he r

etai

ning

liga

men

ts. I

n th

e fa

ce p

rope

r, w

hile

the

pri

n-ci

ples

of

cons

truc

tion

rem

ain

the

sam

e, t

here

is

cons

ider

ably

gr

eate

r co

mpl

exit

y. T

his

is d

ue t

o th

e co

mpa

ctio

n re

sult

ing

from

the

abs

ence

of

forw

ard

pro

ject

ion

of t

he m

idfa

ce,

as

occu

rs i

n ot

her

spec

ies,

and

the

pre

dom

inan

ce o

f th

e or

bita

l an

d o

ral c

avit

ies

that

lim

it th

e av

aila

bilit

y of

a b

ony

plat

form

fo

r at

tach

men

t of l

igam

ents

and

mus

cles

. To

secu

re th

e su

per-

cia

l fa

scia

to

the

faci

al s

kele

ton,

a s

yste

m o

f re

tain

ing

liga-

men

ts b

ind

the

der

mis

to

the

skel

eton

, an

d t

he c

ompo

nent

s of

thi

s sy

stem

pas

s th

roug

h al

l lay

ers

(Fig

s 6.

3, 6

.4).7

,8

The

str

uctu

re a

nd c

ompo

siti

on o

f ea

ch o

f th

e 5

laye

rs w

ill

now

be

des

crib

ed in

tur

n.

Laye

r 1:

ski

nT

he e

pid

erm

is is

a c

ell-

rich

laye

r co

mpo

sed

mai

nly

of d

iffe

r-en

tiat

ing

kera

tino

cyte

s an

d a

sm

alle

r nu

mbe

r of

pig

men

t pro

-d

ucin

g m

elan

ocyt

es a

nd a

ntig

en-p

rese

ntin

g L

ange

rhan

s ce

lls.

The

der

mis

is th

e ou

ter l

ayer

of t

he s

truc

tura

l sup

erc

ial f

asci

a an

d co

mpr

ises

pre

dom

inan

tly

the

extr

acel

lula

r mat

rix

secr

eted

Fig.

6.1

Reg

ions

of t

he fa

ce. T

he m

obile

ant

erio

r fac

e is

func

tiona

lly a

dapt

ed fo

r fa

cial

exp

ress

ions

and

is s

epar

ated

from

the

rela

tivel

y x

ed la

tera

l fac

e (s

hade

d),

whic

h ov

erlie

s m

astic

ator

y st

ruct

ures

. A v

ertic

al li

ne o

f ret

aini

ng li

gam

ents

(red

) se

para

tes

the

ante

rior a

nd la

tera

l fac

e. T

hese

liga

men

ts a

re, f

rom

abo

ve: t

empo

ral,

late

ral o

rbita

l, zy

gom

atic

, mas

sete

ric, a

nd m

andi

bula

r lig

amen

ts. I

n th

e an

terio

r fa

ce, t

he m

id-c

heek

is s

plit

obliq

uely

into

two

sepa

rate

func

tiona

l par

ts b

y th

e m

id-c

heek

gro

ove

(dot

ted

line)

rela

ted

to tw

o ca

vitie

s: th

e pe

riorb

ital p

art a

bove

(b

lue)

and

the

perio

ral p

art b

elow

(yel

low)

. (

Dr L

even

t Efe

, CM

I.)

Fig.

6.2

The

face

is c

onst

ruct

ed o

f ve

bas

ic la

yers

. Thi

s v

e-la

yere

d co

nstru

ct

is m

ost e

vide

nt in

the

scal

p bu

t exis

ts in

the

rest

of t

he fa

ce, w

ith s

igni

can

t m

odi

catio

n an

d co

mpa

ctio

n fo

r fun

ctio

nal a

dapt

atio

n. L

ayer

4 is

the

mos

t si

gni

cant

ly m

odi

ed la

yer,

with

alte

rnat

ing

faci

al s

oft t

issu

e sp

aces

and

reta

inin

g lig

amen

ts. F

acia

l ner

ve b

ranc

hes

also

tran

sitio

n fro

m d

eep

to s

uper

cia

l in

asso

ciat

ion

with

the

reta

inin

g lig

amen

ts th

roug

h la

yer 4

. (

Dr L

even

t Efe

, CM

I.)

80SE

CTIO

N I

Anat

omy

of th

e ag

ing

face

6

The

thi

nner

the

der

mis

, the

mor

e su

scep

tibl

e it

is

to q

ualit

a-ti

ve d

eter

iora

tion

agi

ng c

hang

es.

Laye

r 2:

sub

cuta

neou

s tis

sue

The

sub

cuta

neou

s la

yer

has

two

com

pone

nts:

the

sub

cuta

ne-

ous

fat,

whi

ch p

rovi

des

vol

ume,

and

the

br

ous

reti

nacu

lar

cuti

s th

at b

ind

s th

e d

erm

is to

the

und

erly

ing

SMA

S.9 O

f not

e,

the

reti

nacu

lar

cuti

s is

the

nam

e gi

ven

to t

hat

port

ion

of

the

reta

inin

g lig

amen

t th

at p

asse

s th

roug

h th

e su

bcut

aneo

us

tiss

ues.

The

am

ount

, pr

opor

tion

and

arr

ange

men

t of

eac

h co

mpo

nent

var

y in

dif

fere

nt r

egio

ns o

f th

e fa

ce. I

n th

e sc

alp,

th

e su

bcut

aneo

us la

yer h

as u

nifo

rm th

ickn

ess

and

con

sist

ency

of

xa

tion

to

the

over

lyin

g d

erm

is.

In c

ontr

ast,

in t

he f

ace

prop

er,

the

subc

utan

eous

lay

er h

as s

igni

can

t va

riat

ion

in

thic

knes

s an

d a

ttac

hmen

ts.

In s

peci

aliz

ed a

reas

suc

h as

the

ey

elid

s an

d li

ps, t

his

laye

r is

sign

ica

ntly

com

pact

ed s

uch

that

fa

t may

app

ear n

on-e

xist

ent.

In o

ther

are

as, s

uch

as th

e na

sola

-bi

al s

egm

ent,

it i

s ve

ry t

hick

.4 In

are

as w

ith

thic

k su

bcu-

tane

ous

tiss

ue,

the

reti

nacu

lar

cuti

s le

ngth

ens

sign

ica

ntly

, pr

edis

posi

ng i

ts

bers

to

wea

keni

ng a

nd d

iste

nsio

n w

ith

agin

g. W

ithi

n th

e su

bcut

aneo

us ti

ssue

, the

ove

rall

atta

chm

ent

to th

e ov

erly

ing

der

mis

is s

tron

ger a

nd d

ense

r tha

n th

e at

tach

-m

ent t

o th

e un

der

lyin

g SM

AS.

9 Thi

s is

a r

esul

t of t

he tr

ee-l

ike

arra

ngem

ent

of t

he r

etin

acul

ar c

utis

be

rs (

Fig.

6.3

), w

ith

few

er b

ut t

hick

er

bers

dee

p as

its

ris

es t

hrou

gh t

he S

MA

S th

at p

rogr

essi

vely

div

ide

into

mul

tipl

e n

e m

icro

ligam

ents

as

they

reac

h th

e d

erm

is. T

his

expl

ains

why

it is

eas

ier t

o pe

rfor

m

subc

utan

eous

dis

sect

ion

in t

he d

eepe

r su

bcut

aneo

us l

evel

(ju

st o

n th

e su

rfac

e of

the

und

erly

ing

SMA

S) th

an m

ore

supe

r-c

ially

nea

rer

the

der

mis

, as

ther

e ar

e fe

wer

ret

inac

ular

cut

is

ber

s an

d t

he s

ubcu

tane

ous

fat

here

doe

s no

t at

tach

dir

ectl

y to

the

out

er s

urfa

ce o

f th

e un

der

lyin

g SM

AS.

Furt

herm

ore,

the

ret

inac

ular

cut

is

bers

are

not

uni

form

ac

ross

the

face

, but

var

y in

ori

enta

tion

and

den

sity

acc

ord

ing

to t

he a

nato

my

of t

he u

nder

lyin

g d

eepe

r st

ruct

ures

. As

will

be

app

aren

t w

hen

the

anat

omy

of t

he u

nder

lyin

g L

ayer

4 i

s d

escr

ibed

, at t

he lo

cati

on o

f the

ret

aini

ng li

gam

ents

, the

ver

ti-

cally

ori

enta

ted

ret

inac

ular

cut

is

bers

are

the

mos

t d

ense

an

d a

re t

he m

ost

effe

ctiv

e in

sup

port

ing

for

the

over

lyin

g so

ft

tiss

ues

and

in

so

d

oing

, fo

rms

boun

dar

ies

that

by

brob

last

s. T

ype

I co

llage

n is

the

mos

t ab

und

ant

prot

ein.

O

ther

col

lage

n ty

pes

(III

, V,

VII

), el

asti

n, p

rote

ogly

cans

and

b

rone

ctin

s ar

e pr

esen

t in

sm

alle

r qu

anti

ties

. A r

ich

vasc

ular

pl

exus

is

an i

mpo

rtan

t co

mpo

nent

of

the

der

mis

. T

he t

hick

-ne

ss o

f th

e d

erm

is r

elat

es t

o it

s fu

ncti

on a

nd t

end

s to

be

inve

rsel

y pr

opor

tion

ate

to it

s m

obili

ty. T

he d

erm

is is

thin

nest

in

the

eyel

ids

and

thic

kest

ove

r th

e fo

rehe

ad a

nd th

e na

sal t

ip.

Fig.

6.3

The

reta

inin

g lig

amen

ts o

f the

face

can

be

like

ned

to a

tree

. The

liga

men

ts a

ttach

the

soft

tissu

es to

the

faci

al s

kele

ton

or d

eep

mus

cle

fasc

ia,

pass

ing

thro

ugh

all

ve la

yers

of t

he s

oft t

issu

es. I

t fa

ns o

ut in

a s

erie

s of

bra

nche

s an

d in

serts

into

the

derm

is. A

t diff

eren

t lev

els

of d

isse

ctio

n, it

is g

iven

di

ffere

nt n

ames

, suc

h as

the

retin

acul

ar c

utis

in th

e su

bcut

aneo

us la

yer a

nd li

gam

ents

in th

e su

bSM

AS

leve

l. (

Dr L

even

t Efe

, CM

I.)A

B

Fig.

6.4

Thr

ee m

orph

olog

ical

form

s of

reta

inin

g lig

amen

ts o

f the

face

. (

Dr L

even

t Ef

e, C

MI.)

81Su

rgic

al a

nato

my

of th

e fa

ce, S

MAS

, fac

ial s

pace

s an

d re

tain

ing

ligam

ents

late

ral o

rbit

al th

icke

ning

and

the

mai

n zy

gom

atic

liga

men

t at

its

infe

rola

tera

l bo

rder

and

the

pla

tysm

a at

its

upp

er b

ord

er

by th

e lo

wer

mas

sete

ric

ligam

ent.

The

dee

per

mus

cles

in la

yer

3 pr

ovid

e gr

eate

r fu

ncti

onal

con

trol

of t

he s

phin

cter

s ov

er th

e bo

ny c

avit

ies.

For

the

upp

er t

hird

, the

se a

re t

he c

orru

gato

rs

and

pro

ceru

s, a

nd a

roun

d th

e or

al c

avit

y, th

e el

evat

ors

(zyg

o-m

atic

us m

ajor

and

min

or,

leva

tor

labi

i su

peri

oris

, le

vato

r an

guli

oris

), an

d th

e d

epre

ssor

s (d

epre

ssor

ang

uli o

ris,

dep

ress

or

labi

i inf

erio

ris)

aro

und

the

ora

l sph

inct

er a

nd t

he m

enta

lis.

Laye

r 4

Lay

er 4

is

the

plan

e in

whi

ch d

isse

ctio

n is

per

form

ed i

n su

bSM

AS

face

lifts

. It

is a

n ar

ea o

f si

gni

cant

com

plex

ity

and

co

ntai

ns

the

follo

win

g st

ruct

ures

: (1

) so

ft

tiss

ue

spac

es;

(2) r

etai

ning

liga

men

ts; (

3) d

eep

laye

rs o

f the

intr

insi

c m

uscl

es

pass

ing

from

the

ir b

one

atta

chm

ent

to t

heir

mor

e su

per

cial

so

ft t

issu

e or

igin

; and

(4)

fac

ial n

erve

bra

nche

s, p

assi

ng f

rom

d

eep

to s

uper

cia

l. Fu

ncti

onal

ly, a

ser

ies

of s

oft

tiss

ue s

pace

s ex

ist

in l

ayer

4 t

o al

low

ind

epen

den

t m

ovem

ent

of t

he p

eri-

orbi

tal a

nd p

erio

ral m

uscl

e of

faci

al e

xpre

ssio

ns o

ver

the

dee

p fa

scia

resp

onsi

ble

for m

asti

cati

on d

irec

tly

bene

ath

the

mus

cles

of

fac

ial

expr

essi

on.13

The

ret

aini

ng l

igam

ents

of

the

face

are

st

rate

gica

lly p

lace

d w

ithi

n th

e bo

und

arie

s be

twee

n th

e so

ft

tiss

ue s

pace

s an

d f

unct

ions

to

rein

forc

e th

e bo

und

arie

s (F

ig.

6.6)

. In

the

late

ral f

ace,

imm

edia

tely

in fr

ont o

f the

ear

, ext

end

-in

g 25

30

mm

for

war

d o

f th

e ea

r ca

rtila

ge t

o th

e po

ster

ior

bord

er o

f the

pla

tysm

a, is

a d

iffu

se a

rea

of li

gam

ento

us a

ttac

h-m

ent,

des

crib

ed b

y Fu

rnas

as

the

plat

ysm

a au

ricu

lar

fasc

ia

(PA

F).7

As

no f

acia

l ex

pres

sion

occ

urs

here

, the

der

mis

, sub

-cu

tane

ous

tiss

ue, S

MA

S an

d t

he u

nder

lyin

g pa

roti

d c

apsu

le

(lay

ers

15)

are

bou

nd t

oget

her

as a

n ar

ea o

f re

tain

ing

liga-

men

t. L

ayer

4 i

s re

duc

ed t

o a

laye

r of

fus

ion

here

, wit

hout

a

soft

tis

sue

spac

e. T

he li

gam

ento

us c

hara

cter

of

this

imm

obile

Fig.

6.5

The

den

sity

and

stre

ngth

of t

he re

tinac

ular

cut

is

bers

in th

e su

bcut

aneo

us

laye

r var

ies

in d

iffer

ent a

reas

of t

he fa

ce. W

here

it o

verli

es th

e re

tain

ing

ligam

ents

, th

e b

ers

are

dens

er a

nd o

rient

ed m

ore

verti

cally

. In

thes

e ar

eas,

sha

rp re

leas

e is

us

ually

nec

essa

ry to

rais

e a

subc

utan

eous

ap

. In

cont

rast

, in

area

s ov

erly

ing

a sp

ace,

the

ber

s ar

e le

ss d

ense

and

orie

nted

mor

e ho

rizon

tally

. Her

e, it

is re

lativ

ely

easy

to e

leva

te a

sub

cuta

neou

s fa

celif

t ap

. (

Dr L

even

t Efe

, CM

I.)

Fig.

6.6

Top

ogra

phic

al a

nato

my

of la

yer 4

ove

r the

late

ral f

ace.

Spa

ces

(blu

e),

ligam

ents

(red

) and

the

area

s of

impo

rtant

ana

tom

y (s

tippl

ed).

The

larg

est a

rea

of

liga

men

tous

atta

chm

ent,

the

plat

ysm

a-au

ricul

ar fa

scia

(PAF

), do

min

ates

the

post

erio

r par

t of l

evel

4 a

t the

leas

t mob

ile p

art o

f the

face

. The

late

ral f

ace

trans

ition

s in

to th

e an

terio

r fac

e at

the

verti

cal l

ine

of re

tain

ing

ligam

ents

. Im

med

iate

ly a

bove

and

bel

ow th

e ar

ch o

f the

zyg

oma

are

the

trian

gula

r-sha

ped

area

s th

at c

onta

in th

e im

porta

nt a

nato

my

proc

eedi

ng fr

om th

e la

tera

l int

o th

e an

terio

r fac

e. (

Dr L

even

t Efe

, CM

I.)

com

part

men

taliz

e th

e su

bcut

aneo

us f

at. T

hese

are

as, s

uch

as

the

so-c

alle

d M

cGre

gor

s pa

tch

over

the

bod

y of

the

zygo

ma,

of

ten

requ

ire

shar

p re

leas

e to

mob

ilize

. In

bet

wee

n th

ese

reta

inin

g lig

amen

ts in

laye

r 4

are

loca

ted

the

soft

tiss

ue s

pace

s of

the

fac

e, t

hat

faci

litat

e th

e m

obili

ty o

f th

e su

per

cial

fas

cia

over

the

dee

p fa

scia

. W

here

the

sub

cuta

neou

s fa

t ov

erlie

s a

spac

e, t

he r

etin

acul

ar

bers

are

les

s d

ense

and

ori

enta

ted

m

ore

hori

zont

ally

, as

a r

esul

t of

whi

ch,

the

tiss

ues

tend

to

sepa

rate

wit

h re

lati

ve e

ase,

oft

en w

ith

just

sim

ple

blun

t ng

er

dis

sect

ion

(Fig

. 6.5

). T

his

vari

atio

n in

the

den

sity

and

ori

enta

-ti

on o

f th

e re

tina

cula

r cu

tis

ber

s in

the

sub

cuta

neou

s fa

t is

th

e an

atom

ical

bas

is fo

r th

e co

mpa

rtm

enta

lizat

ion

of th

e su

b-cu

tane

ous

fat

into

dis

cret

e co

mpa

rtm

ents

, des

crib

ed in

det

ail

in C

hapt

er 1

1.1.

10,1

1

Laye

r 3:

mus

culo

-apo

neur

otic

laye

rT

he m

uscl

es o

f fa

cial

exp

ress

ion

are

uniq

ue a

nd f

und

amen

-ta

lly d

iffe

rent

fro

m s

kele

tal

mus

cles

ben

eath

the

dee

p fa

scia

be

caus

e th

ey a

re s

itua

ted

wit

hin

the

supe

rci

al f

asci

a an

d

they

mov

e th

e so

ft ti

ssue

s of

whi

ch th

ey a

re a

par

t. A

ll m

uscl

es

of f

acia

l ex

pres

sion

hav

e ei

ther

all

or t

he m

ajor

ity

of t

heir

co

urse

wit

hin

laye

r 3 a

nd th

ey a

re p

red

omin

antl

y lo

cate

d o

ver

and

aro

und

the

orb

ital

and

ora

l ca

viti

es.

In t

he p

roto

type

sc

alp,

the

occi

pita

l-fr

onta

lis m

oves

the

over

lyin

g so

ft ti

ssue

of

the

fore

head

, w

hile

its

und

ersu

rfac

e gl

ides

ove

r th

e su

bap-

oneu

roti

c sp

ace

(lay

er 4

). L

ayer

3 is

con

tinu

ous

over

the

enti

re

face

, al

thou

gh f

or d

escr

ipti

ve p

urpo

ses,

dif

fere

nt n

ames

are

gi

ven

to c

erta

in p

arts

acc

ord

ing

to t

he s

uper

cia

l m

uscl

e w

ithi

n. I

t is

cal

led

the

gal

ea o

ver

the

scal

p, t

he t

empo

ro-

pari

etal

(su

per

cial

tem

pora

l) f

asci

a ov

er t

he t

empl

e, t

he

orbi

cula

ris

fasc

ia in

the

peri

orbi

tal r

egio

n, th

e su

per

cial

mus

-cu

loap

oneu

roti

c sy

stem

(SM

AS)

ove

r th

e m

id- a

nd lo

wer

face

an

d p

laty

sma

in t

he n

eck.

5,12

Wit

hin

laye

r 3, t

he fa

cial

mus

cles

them

selv

es h

ave

a la

yere

d

con

gura

tion

, wit

h th

e br

oad

, at

mus

cles

form

ing

the

supe

r-c

ial

laye

r th

at c

over

s th

e an

teri

or a

spec

t of

the

fac

e. T

he

fron

talis

cov

ers

the

uppe

r, or

bicu

lari

s oc

uli,

the

mid

dle

and

th

e pl

atys

ma,

and

low

er t

hird

s, r

espe

ctiv

ely.

The

mus

cles

of

this

lay

er h

ave

min

imal

dir

ect

atta

chm

ent

to t

he b

one,

sta

bi-

lized

to th

e sk

elet

on a

t the

ir p

erip

hery

ind

irec

tly

by th

e ve

rti-

cally

ori

enta

ted

ret

aini

ng l

igam

ents

as

note

d e

arlie

r. T

he

fron

talis

is

xed

alo

ng th

e su

peri

or te

mpo

ral l

ine

by th

e su

pe-

rior

tem

pora

l se

ptum

, th

e or

bicu

lari

s oc

uli

late

rally

by

the

82SE

CTIO

N I

Anat

omy

of th

e ag

ing

face

6

area

mak

es it

sur

gica

lly u

sefu

l for

sut

ure

xa

tion

. Fur

nas

had

or

igin

ally

des

crib

ed t

he l

ower

par

t of

the

PA

F, t

he p

laty

sma

auri

cula

r lig

amen

t,7 a

lso

nam

ed b

y St

uzin

and

col

leag

ues,

the

paro

tid

cut

aneo

us l

igam

ent5

and

thi

s lig

amen

t w

as s

ubse

-qu

entl

y na

med

the

tym

pano

paro

tid

fas

cia.

14 T

he p

art

of t

he

PAF

imm

edia

tely

in fr

ont o

f the

low

er tr

agus

has

bee

n la

bele

d,

Lor

es

fasc

ia.14

In c

ontr

ast,

in th

e an

teri

or fa

ce w

here

ther

e is

con

sid

erab

le

mov

emen

t ov

er a

nd a

roun

d t

he b

ony

cavi

ties

, the

lig

amen

ts

are

sign

ica

ntly

com

pact

ed a

nd a

rran

ged

aro

und

the

ed

ges

of t

he b

ony

cavi

ties

. The

se b

ound

arie

s pr

ovid

e th

e la

st p

osi-

tion

whe

re t

here

is

und

erly

ing

dee

p fa

scia

for

the

mob

ile

shut

ters

of

the

lids

and

lips

to

be s

uppo

rted

. Im

port

antl

y fo

r th

e su

rgeo

n, t

he r

etai

ning

lig

amen

ts a

lso

act

as t

rans

itio

n po

ints

for

the

fac

ial

nerv

e br

anch

es t

o pa

ss f

rom

dee

p to

su

per

cial

, on

thei

r w

ay t

o in

nerv

ate

thei

r ta

rget

mus

cles

.So

ft t

issu

e sp

aces

of

the

face

are

in

two

form

s: (

1) t

hose

ov

erly

ing

bony

cav

itie

s, s

uch

as t

he p

rese

ptal

spa

ce o

f th

e ey

elid

ove

r th

e or

bit a

nd th

e ve

stib

ule

of th

e or

al c

avit

y, u

nder

th

e lip

s an

d t

he l

ower

nas

olab

ial

segm

ent

of t

he c

heek

and

(2

) th

ose

over

lyin

g th

e bo

ne,

whe

re s

oft

tiss

ue s

pace

s al

low

th

e ov

erly

ing

supe

rci

al f

asci

a to

glid

e fr

eely

ove

r th

e bo

ne.

Laye

r 5

The

dee

p fa

scia

, th

e d

eepe

st s

oft

tiss

ue l

ayer

of

the

face

, is

fo

rmed

by

the

peri

oste

um w

here

it

over

lies

bone

. O

ver

the

late

ral f

ace,

whe

re t

he m

uscl

e of

mas

tica

tion

(te

mpo

ralis

and

m

asse

ter)

ove

rlie

the

bone

, the

dee

p fa

scia

is in

stea

d th

e fa

scia

l co

veri

ng o

f th

e m

uscl

es, t

he d

eep

tem

pora

l fa

scia

abo

ve t

he

zygo

mat

ic a

rch,

and

mas

sete

ric

fasc

ia b

elow

the

arc

h. T

he

paro

tid

fas

cia

is a

lso

part

of

the

dee

p fa

scia

. T

he i

nves

ting

d

eep

cerv

ical

fas

cia

is t

he c

orre

spon

din

g la

yer

in t

he n

eck

whe

re it

cov

ers

the

supr

aom

ohyo

id m

uscl

es a

nd s

plit

s to

form

th

e su

bman

dib

ular

spa

ce t

hat

cont

ains

the

sub

man

dib

ular

gl

and

. The

dee

p fa

scia

, alt

houg

h th

in, i

s to

ugh

and

uny

ield

ing

and

giv

es a

ttac

hmen

t to

the

reta

inin

g lig

amen

ts o

f the

face

. In

the

mob

ile s

hutt

ers

over

the

bon

y ca

viti

es, t

he d

eep

fasc

ia i

s ab

sent

, be

ing

repl

aced

by

a m

obile

lin

ing

der

ived

fro

m t

he

cavi

ties

, tha

t of

the

con

junc

tiva

or

oral

muc

osa.

Anat

omy

over

the

cavi

ties

in

the

skel

eton

The

gen

eral

pat

tern

of

the

ve-

laye

red

ana

tom

y is

mod

ied

w

here

the

sof

t ti

ssue

s ov

erlie

the

orb

ital

, ora

l and

nas

al c

avi-

ties

ove

r th

e an

teri

or fa

ce (F

ig. 6

.7).

Onl

y th

e ou

ter

thre

e la

yers

of

the

com

posi

te c

onti

nue

from

the

peri

pher

y as

the

soft

tiss

ue

over

the

cav

itie

s. T

he S

MA

S la

yer

wit

hin

this

com

posi

te

incl

udes

the

sph

inct

eric

orb

icul

aris

mus

cles

tha

t ex

tend

rig

ht

to t

he f

ree

edge

of

the

soft

tis

sue

aper

ture

of

the

eyel

ids

and

lip

s. T

he r

etai

ning

liga

men

ts, w

hich

are

suc

h a

key

feat

ure

of

the

ve-

laye

red

ana

tom

y, a

re n

ot p

rese

nt o

ver

the

cavi

ties

. T

here

are

thus

ana

tom

ical

var

iati

ons

asso

ciat

e w

ith

thee

func

-ti

onal

tra

nsit

ions

fro

m t

he r

elat

ive

stab

ility

of

the

xe

d

area

s to

the

hig

h m

obili

ty o

f th

e so

ft t

issu

e sh

utte

rs o

ver

the

cavi

ties

. At

the

tran

siti

on, t

o su

ppor

t th

e sh

utte

rs, t

he r

etai

n-in

g lig

amen

ts a

re c

ond

ense

d a

long

the

bon

y or

bita

l rim

(Fi

g.

6.8)

. Thi

s is

the

ana

tom

ical

bas

is f

or t

he p

erio

rbit

al l

igam

ent

arou

nd th

e or

bit,

of w

hich

the

low

er li

d p

art i

s th

e or

bicu

lari

s

Fig.

6.7

The

ana

tom

y ov

er th

e sk

elet

on a

nd o

ver b

ony

cavi

ties

(15

), sh

owin

g th

e re

latio

nshi

p of

the

soft

tissu

e sp

aces

to b

ony

cavi

ty s

pace

s. (

Dr L

even

t Efe

, CM

I.)

Fig.

6.8

The

sys

tem

of r

etai

ning

liga

men

ts s

ituat

ed a

roun

d th

e bo

ny c

aviti

es

stab

ilize

s th

e so

ft tis

sue

over

the

cavi

ties.

( D

r Lev

ent E

fe, C

MI.)

83Fa

cial

spa

ces

the

low

er

tria

ngul

ar

shap

ed

tem

pora

l ar

ea

that

co

ntai

ns

impo

rtan

t an

atom

y, b

y th

e in

feri

or t

empo

ral

sept

um (

ITS)

. T

hese

sep

ti m

erge

at

the

tria

ngul

ar-s

hape

d z

one

of a

dhe

sion

ca

lled

the

tem

pora

l (o

rbit

al)

ligam

ent.1

5 T

he u

pper

tem

pora

l sp

ace

prov

ides

saf

e su

rgic

al a

cces

s to

the

lat

eral

bro

w a

nd

uppe

r m

id-c

heek

. The

spa

ce c

an b

e re

adily

ope

ned

by

blun

t d

isse

ctio

n to

its

bou

ndar

ies.

Onc

e id

enti

ed

, the

bou

ndar

ies

are

then

rel

ease

d b

y pr

ecis

e sh

arp

dis

sect

ion.

The

sup

erio

r te

mpo

ral s

eptu

m c

an b

e re

leas

ed s

harp

ly, t

akin

g ca

re o

nly

to

pres

erve

the

lat

eral

(d

eep)

bra

nch

of t

he s

upra

orbi

tal

nerv

e,

whi

ch r

uns

para

llel t

o th

e se

ptum

abo

ut 0

.5 c

m m

edia

l to

it.19

T

he in

feri

or te

mpo

ral s

eptu

m p

rovi

des

a m

arke

r to

the

impo

r-ta

nt a

nato

my

here

as

the

tem

pora

l bra

nche

s of

the

faci

al n

erve

ar

e lo

cate

d p

aral

lel t

o an

d im

med

iate

ly in

feri

or to

this

sep

tum

. To

rel

ease

the

infe

rior

tem

pora

l sep

tum

, the

roo

f of

the

spa

ce

is g

entl

y lif

ted

off

the

dee

p te

mpo

ral f

asci

a

oor,

whi

ch th

ree-

dim

ensi

onal

izes

the

sep

tum

in

prep

arat

ion

for

its

gent

le

rele

ase

at t

he l

evel

of

the

oo

r, be

arin

g in

min

d t

he f

ront

al

bran

ches

are

loca

ted

und

er th

e ro

of o

f the

low

er te

mpo

ral a

rea

whe

re t

hey

trav

el i

n th

e ce

iling

wit

hin

the

laye

r of

fat

sus

-pe

nded

on

the

und

ersi

de

of t

he t

empo

ropa

riet

al f

asci

a. O

nce

rele

ased

, the

sen

tine

l vei

n co

mes

into

vie

w. T

he s

enti

nel v

ein

is n

ot a

goo

d la

ndm

ark

for

loca

ting

the

tem

pora

l bra

nche

s as

th

ey c

ours

e ce

phal

ad to

the

vein

, tha

t is,

infe

rior

to th

e in

feri

or

tem

pora

l sep

tum

. Thi

s an

atom

y is

als

o re

view

ed in

Cha

pter

7.

reta

inin

g lig

amen

t, w

hich

sta

biliz

es th

e or

bicu

lari

s oc

uli t

o th

e or

bita

l ri

m p

erio

steu

m.

Aro

und

the

ora

l ca

vity

whe

re t

he

boun

dar

y is

less

dis

tinc

t, th

e lig

amen

ts a

rise

mai

nly

from

the

plat

form

of t

he b

ody

of th

e zy

gom

a, a

nd fr

om th

e d

eep

fasc

ia

over

the

mas

sete

r.15

17

The

dee

per

com

pone

nt o

f th

e ey

elid

and

lip

s ar

e d

eriv

ed

from

the

ori

gin

of t

he c

avit

y an

d a

re n

ot a

n ex

tens

ion

of

the

faci

al s

oft

tiss

ues.

In

the

eyel

id,

the

dee

per

lid m

uscl

es

wit

h th

eir

rela

ted

apo

neur

osis

(le

vato

r an

d c

apsu

lopa

lpeb

ral

fasc

iae)

and

fat a

re re

tain

ed b

y th

e fa

scia

l sys

tem

of t

he s

eptu

m

orbi

tale

. The

free

ed

ges

of th

e up

per

and

low

er e

yelid

s ob

tain

th

eir

ligam

ento

us s

uppo

rt f

rom

the

tar

sal

plat

es,

wit

h th

eir

cant

hal

tend

on a

ttac

hmen

ts t

o th

e m

edia

l an

d l

ater

al o

rbit

al

rim

s. I

n th

e pr

etar

sal a

rea,

the

sup

erc

ial a

nd d

eep

lid s

truc

-tu

res,

the

ante

rior

and

pos

teri

or la

mel

lae,

mer

ge. B

ut b

etw

een

the

pret

arsa

l ar

ea o

f th

e lid

and

the

orb

ital

rim

the

lam

ella

e re

mai

n qu

ite

sepa

rate

, i.e

., th

e pr

esep

tal

orbi

cula

ris

doe

s no

t ha

ve a

n at

tach

men

t to

the

sep

tum

orb

ital

e. T

his

is t

he a

na-

tom

ical

bas

is f

or th

e, s

urgi

cally

sig

nic

ant,

pres

epta

l spa

ce o

f th

e lo

wer

lid

. In

the

uppe

r lid

, the

re is

not

an

equi

vale

nt s

pace

as

the

subm

uscu

lar

fat p

ad o

ver

the

supe

rior

orb

ital

rim

con

-ti

nues

on

the

oute

r su

rfac

e of

the

sep

tum

orb

ital

e w

here

it

is a

dhe

rent

to

the

over

lyin

g fa

scia

on

the

und

ersi

de

of t

he

orbi

cula

ris

alm

ost

dow

n to

whe

re t

he l

evat

or c

ross

es i

nto

the

orbi

cula

ris.

The

ext

ent

of t

he v

esti

bule

of

the

oral

cav

ity

cove

ring

the

m

axill

a an

d t

he m

and

ible

has

a m

ajor

im

pact

on

the

susc

ep-

tibi

lity

to a

ging

of

the

over

lyin

g so

ft t

issu

e. T

he s

kele

ton

und

erly

ing

the

spac

e is

not

ava

ilabl

e to

pro

vid

e lig

amen

tous

at

tach

men

t for

sup

port

of t

he s

oft t

issu

es th

at c

over

this

larg

e ar

ea. T

he e

xtre

me

mob

ility

of

the

lip a

nd a

dja

cent

par

t of

the

ch

eek

rend

ers

it s

usce

ptib

le t

o ag

ing

chan

ges

and

the

ind

ica-

tion

for

a l

ower

fac

elif

t is

lar

gely

to

corr

ect

agin

g ch

ange

s in

th

is u

nsup

port

ed t

issu

e.

Faci

al s

pace

sA

lar

ge p

art

of t

he s

ubSM

AS

laye

r 4

cons

ists

of

soft

tis

sue

spa

ces.

T

hese

spa

ces

have

de

ned

bou

ndar

ies

that

are

str

a-te

gica

lly r

einf

orce

d b

y re

tain

ing

ligam

ents

.18 S

igni

can

tly,

th

ese

area

s ar

e by

de

niti

on a

nato

mic

ally

sa

fe s

pace

s t

o d

isse

ct, a

s no

str

uctu

res

cros

ses

wit

hin

and

all

bran

ches

of t

he

faci

al n

erve

are

out

sid

e th

ese

spac

es. A

s th

e ro

of o

f eac

h sp

ace

is t

he l

east

sup

port

ed p

art,

it i

s m

ore

pron

e to

dev

elop

ing

laxi

ty w

ith

agin

g, c

ompa

red

wit

h th

e lig

amen

t-re

info

rced

bo

und

arie

s. T

his

dif

fere

ntia

l la

xity

acc

ount

s fo

r m

uch

of t

he

char

acte

rist

ic c

hang

es th

at o

ccur

wit

h ag

ing

of th

e fa

ce. O

nce

a sp

ace

has

been

sur

gica

lly d

ene

d t

o it

s bo

und

arie

s, t

he

reta

inin

g lig

amen

ts i

n th

e bo

und

ary

can

then

be

prec

isel

y re

leas

ed u

nder

dir

ect

visi

on t

o ac

hiev

e th

e d

esir

ed m

obili

za-

tion

, w

hile

pre

serv

ing

the

vita

l st

ruct

ures

clo

sely

ass

ocia

ted

w

ith

the

ligam

ents

. A b

rief

des

crip

tion

of

surg

ical

ly s

igni

-ca

nt f

acia

l sof

t ti

ssue

spa

ces

is g

iven

bel

ow.

Uppe

r te

mpo

ral s

pace

The

up

per

tem

pora

l sp

ace

sepa

rate

s th

e te

mpo

ropa

riet

al

fasc

ia (

supe

rci

al t

empo

ral

fasc

ia)

from

the

(d

eep)

tem

pora

l fa

scia

and

is s

epar

ated

from

the

fore

head

by

the

supe

rior

tem

-po

ral s

eptu

m (S

TS)

alo

ng th

e su

peri

or te

mpo

ral l

ine

(Fig

. 6.9

). A

nter

oinf

erio

rly,

the

upp

er t

empo

ral s

pace

is s

epar

ated

fro

m

Fig.

6.9

The

upp

er te

mpo

ral s

pace

and

the

reta

inin

g lig

amen

ts o

f the

tem

ple.

The

bo

unda

ries

of th

e sp

ace

are

the

supe

rior t

empo

ral s

eptu

m (S

TS) a

nd th

e in

ferio

r te

mpo

ral s

eptu

m (I

TS),

whic

h ar

e ex

tens

ions

of t

he te

mpo

ral l

igam

ent a

dhes

ion

(TLA

). No

stru

ctur

es c

ross

the

tem

pora

l spa

ce. T

he T

LA c

ontin

ues

med

ially

as

the

supr

aorb

ital l

igam

ento

us a

dhes

ion

(SLA

). In

ferio

r to

the

tem

pora

l spa

ce is

the

trian

gula

r-sha

ped

area

of i

mpo

rtant

ana

tom

y (s

tippl

ed).

Cros

sing

leve

l 4 in

this

ar

ea a

re th

e m

edia

l and

late

ral b

ranc

hes

of th

e zy

gom

atic

tem

pora

l ner

ve (Z

TN) a

nd

the

sent

inel

vei

n. T

he te

mpo

ral b

ranc

hes

of th

e fa

cial

ner

ve (T

FN) c

ours

e on

the

unde

rsid

e of

the

tem

pora

l-par

ieta

l fas

cia

over

the

area

imm

edia

tely

infe

rior t

o th

e in

ferio

r tem

pora

l sep

tum

. The

per

iorb

ital s

eptu

m (P

S, g

reen

) is

on th

e or

bita

l rim

at

the

boun

dary

of t

he o

rbita

l cav

ity. T

he la

tera

l orb

ital t

hick

enin

g (L

OT) a

nd th

e la

tera

l ro

w th

icke

ning

(LBT

) are

par

ts o

f the

per

iorb

ital s

eptu

m. S

ON, s

upra

orbi

tal n

erve

; ZF

N, z

ygom

atic

ofac

ial n

erve

. (

Dr L

even

t Efe

, CM

I.)

84SE

CTIO

N I

Anat

omy

of th

e ag

ing

face

6

plan

e al

low

s op

enin

g of

the

jaw

wit

hout

rest

rict

ion

and

avo

ids

exce

ssiv

e d

isto

rtio

n of

the

ove

rlyi

ng s

oft

tiss

ues.

The

roo

f of

th

is s

pace

is f

orm

ed b

y th

e pl

atys

ma.

The

low

er p

rem

asse

ter

spac

e ha

s pr

ofou

nd c

linic

al s

igni

can

ce, a

s it

is th

e an

atom

ical

ba

sis

for

the

dev

elop

men

t of

jow

ls w

ith

agin

g. L

axit

y in

the

ro

of o

f the

spa

ce, p

arti

cula

rly

whe

re it

has

a w

eake

ned

att

ach-

men

t to

the

ante

rior

mas

sete

r by

the

mas

sete

ric

ligam

ents

and

it

s in

feri

or b

ound

ary

whe

re th

ere

is n

o lig

amen

t, m

anif

ests

as

the

labi

oman

dib

ular

fold

and

jow

l, re

spec

tive

ly. T

he re

lati

vely

st

able

xa

tion

at

the

ante

roin

feri

or c

orne

r of

the

pre

mas

sete

r sp

ace

prov

ided

by

the

man

dib

ular

liga

men

t ac

coun

ts f

or t

he

dim

ple

that

is c

omm

only

see

n se

para

ting

the

labi

oman

dib

ular

fo

ld a

bove

and

the

jow

l bel

ow.

Bucc

al s

pace

Thi

s is

one

of

the

dee

p fa

cial

spa

ces,

bei

ng,

like

the

sub-

man

dib

ular

spa

ce (w

hich

con

tain

s th

e su

bman

dib

ular

gla

nd),

dee

p to

the

dee

p fa

scia

(la

yer

5). T

he b

ucca

l sp

ace

is l

ocat

ed

in t

he a

nter

ior

face

, med

ial t

o th

e an

teri

or b

ord

er o

f th

e m

as-

sete

r ab

ove

the

leve

l of

the

oral

com

mis

sure

in y

outh

.20,2

1 The

sp

ace

and

its

cont

ents

, the

buc

cal f

at, f

acili

tate

s m

ovem

ent

of

the

over

lyin

g na

sola

bial

seg

men

t of

the

mid

-che

ek a

s w

ell a

s bu

ffer

ing

this

are

a fr

om e

xces

sive

mot

ion

from

jaw

mov

e-m

ent.

Agi

ng a

nd a

ttri

tion

of

the

boun

dar

ies,

par

ticu

larl

y of

th

e m

asse

teri

c lig

amen

ts i

nfer

iorl

y re

sult

in

the

plat

ysm

a

Fig.

6.1

0 Th

e pr

ezyg

omat

ic s

pace

ove

rlies

the

body

of t

he z

ygom

a. T

he o

rigin

of

the

zygo

mat

ic m

uscl

es e

xtend

s un

der t

he

oor.

The

roof

is fo

rmed

by

the

orbi

cula

ris o

culi

line

by th

e su

borb

icul

aris

ocu

li fa

t (SO

OF).

The

uppe

r lig

amen

tous

bo

rder

form

ed b

y th

e or

bicu

laris

reta

inin

g lig

amen

t is

not a

s st

rong

as

the

zygo

mat

ic li

gam

ent r

einf

orce

d lo

wer b

orde

r. (

Dr L

even

t Efe

, CM

I.)

Fig.

6.1

1 Th

e rh

ombo

idal

-sha

ped

prem

asse

ter s

pace

ove

rlies

the

lowe

r hal

f of t

he

mas

sete

r. Th

e ro

of o

f the

spa

ce is

form

ed b

y th

e pl

atys

ma.

The

pos

terio

r bor

der i

s de

ned

by

the

ante

rior e

dge

of th

e st

rong

PAF

and

the

ante

rior b

orde

r is

rein

forc

ed

by th

e m

asse

teric

liga

men

ts n

ear t

he a

nter

ior e

dge

of th

e m

asse

ter.

The

infe

rior

boun

dary

is m

esen

teric

-like

and

doe

s no

t con

tain

any

liga

men

t. W

eakn

ess

of

atta

chm

ent o

f the

pla

tysm

a ro

of a

t the

infe

rior b

ound

ary

lead

s to

the

form

atio

n

of th

e jo

wl d

irect

ly b

ehin

d th

e st

rong

man

dibu

lar l

igam

ent.

The

bucc

al s

pace

co

ntai

ning

the

bucc

al fa

t is

ante

rior t

o th

e up

per m

asse

teric

liga

men

ts. A

ll fa

cial

ne

rve

bran

ches

cou

rse

arou

nd a

nd o

utsi

de th

e sp

ace.

The

sur

gica

lly im

porta

nt

man

dibu

lar b

ranc

h, a

fter l

eavi

ng th

e x

ed P

AF, c

ours

es u

nder

the

infe

rior b

ound

ary

of th

e sp

ace,

then

rise

s on

to th

e hi

ghly

mob

ile o

uter

sur

face

of t

he m

esen

teric

in

ferio

r bor

der b

efor

e re

achi

ng th

e m

andi

bula

r lig

amen

t. (

Dr L

even

t Efe

, CM

I.)

Prez

ygom

atic

spa

ceT

his

tria

ngul

ar-s

hape

d s

pace

ove

rlie

s th

e bo

dy

of th

e zy

gom

a,

its

oo

r co

veri

ng t

he o

rigi

ns o

f th

e zy

gom

atic

mus

cles

. T

he

spac

e al

low

s th

e in

dep

end

ent d

ispl

acem

ent o

f the

orb

icul

aris

oc

uli

(par

s or

bita

le)

in t

he r

oof

from

the

zyg

omat

ic m

uscl

es

und

er

the

oo

r. C

ontr

acti

on

of

the

over

lyin

g or

bicu

lari

s el

evat

es

the

prez

ygom

atic

so

ft

tiss

ues,

w

hich

re

sult

s in

zy

gom

atic

sm

ile li

nes

(bel

ow th

e cr

ows

feet

) (Fi

g. 6

.10)

. Wit

h th

e la

xity

of

agin

g th

e ro

of o

f th

e sp

ace

rest

s at

a lo

wer

leve

l th

an in

you

th. A

s a

resu

lt, t

here

is a

now

a g

reat

er a

mpl

itud

e of

mov

emen

t on

orb

icul

aris

con

trac

tion

tha

t ha

s th

e ef

fect

of

exag

gera

ting

the

zyg

omat

ic l

ines

wit

h ag

ing.

13,1

6 T

his

agin

g of

the

pre

zygo

mat

ic s

pace

, wit

h bu

lgin

g ov

er i

ts r

oof

acce

n-tu

ated

by

its

wel

l-su

ppor

ted

bou

ndar

ies,

is

the

anat

omic

al

basi

s fo

r th

e cl

inic

al e

ntit

y va

riou

sly

des

crib

ed a

s m

alar

m

ound

s, b

ags

or m

alar

cre

scen

t. T

hese

def

orm

itie

s in

dic

ate

the

pres

ence

of s

igni

can

t lax

ity

and

the

trea

tmen

t is

dir

ecte

d

to t

ight

enin

g th

e la

xity

of

the

roof

and

upp

er l

igam

ento

us

boun

dar

y.

Prem

asse

ter

spac

eT

his

spac

e ov

erlie

s th

e lo

wer

hal

f of t

he m

asse

ter

and

is a

nalo

-go

us t

o th

e te

mpo

ral s

pace

, in

that

it o

verl

ies

the

dee

p fa

scia

of

a m

uscl

e of

mas

tica

tion

(Fig

. 6.1

1).18

Thi

s gl

idin

g so

ft ti

ssue

85Fa

cial

ner

ve b

ranc

hes

surg

ical

tra

nsec

tion

of

the

SMA

S he

re,

so-c

alle

d h

igh

SMA

S tr

anse

ctio

n (i

.e.,

at o

r ab

ove

the

arch

) ha

s be

en g

ener

ally

dis

-co

urag

ed. I

t is

now

app

aren

t tha

t the

ner

ve is

dee

per

than

was

pr

evio

usly

thou

ght a

s it

cro

sses

the

zygo

mat

ic a

rch.

30 A

his

to-

logi

cal s

tud

y co

nrm

ed th

at th

e fr

onta

l bra

nche

s ar

e in

tran

si-

tion

fro

m w

here

the

y ex

it t

he p

arot

id b

elow

the

zyg

omat

ic

arch

, to

whe

re th

ey e

nter

the

und

ersi

de

of th

e te

mpo

ropa

riet

al

fasc

ia s

ome

2 cm

abo

ve th

e ar

ch. T

hey

cour

se in

a ti

ssue

laye

r (l

ayer

4),

just

dee

p to

the

tem

poro

pari

etal

fas

cia

(lay

er 3

) an

d

imm

edia

tely

sup

erc

ial t

o th

e pe

rios

teum

and

abo

ve th

at, t

he

tem

pora

lis f

asci

a (l

ayer

5),

all

alon

g pr

otec

ted

by

a fa

scia

l, fa

tty

laye

r, w

hich

is

an u

pwar

d p

rolo

ngat

ion

of t

he p

arot

id-

mas

sete

ric

fasc

ia a

nd n

amed

the

par

otid

-tem

pora

l fa

scia

.27

Ano

ther

stu

dy

note

d t

he t

empo

ral

bran

ch t

o tr

ansi

tion

to

und

er t

he t

empo

ropa

riet

al f

asci

a (l

ayer

3)

at a

dis

tanc

e of

1.

53

cm a

bove

the

zyg

omat

ic a

rch.

31 T

he t

empo

ral

bran

ch

com

plet

es th

e tr

ansi

tion

to th

e un

der

sid

e of

the

tem

poro

pari

-et

al fa

scia

wel

l bef

ore

the

nerv

e cr

osse

s ce

phal

ad to

the

sent

i-ne

l ve

in.15

Acc

ord

ingl

y, o

nce

the

sent

inel

vei

n is

vis

ualiz

ed

from

th

e te

mpo

ral

aspe

ct,

the

tem

pora

l br

anch

es

wou

ld

alre

ady

be lo

cate

d in

the

roo

f of

the

low

er t

empo

ral a

rea.

The

zyg

omat

ic b

ranc

h ex

its

the

paro

tid

gla

nd d

eep

to t

he

dee

p fa

scia

just

bel

ow th

e zy

gom

a an

d c

epha

lad

to th

e pa

roti

d

duc

t. It

tra

vels

hor

izon

tally

on

the

mas

sete

r w

ith

the

tran

s-ve

rse

faci

al a

rter

y.32

,33

At

the

late

ral

bord

er o

f th

e or

igin

of

zygo

mat

icus

m

ajor

m

uscl

e is

th

e su

bsta

ntiv

e zy

gom

atic

re

tain

ing

ligam

ent

(tha

t at

tach

es t

o th

e bo

dy

of t

he z

ygom

a).

At

the

late

ral

bord

er o

f zy

gom

atic

us m

ajor

, af

ter

a br

anch

is

giv

en o

ff t

o su

pply

the

orb

icul

aris

ocu

li, e

nter