330
UNIT 2
Covering, Support, and Movement of the Body
10
MUSCLE GALLERY
Table 10.1
Muscles of the Head, Part I: Facial Expression
(Figure 10.7)
(continued)
MUSCLE
DESCRIPTION
ORIGIN (O) AND
INSERTION (I)
ACTION
NERVE
SUPPLY
Orbicularis oculi
(or-bik
9
u-lar-is ok
9
u-li)
(
orb
5
circular;
ocul
5
eye)
Thin, flat sphincter muscle
of eyelid; surrounds rim of
the orbit
O—frontal and maxillary
bones and ligaments
around orbit
I—tissue of eyelid
Closes eye
; various
parts can be activated
individually; produces
blinking and squinting;
draws eyebrows inferiorly
Facial nerve (cranial VII)
Zygomaticus
—major and
minor (zi-go-mat
9
ı˘-kus)
(
zygomatic
5
cheekbone)
Muscle pair extending
diagonally from cheekbone
to corner of mouth
O—zygomatic bone
I—skin and muscle at
corner of mouth
Raises lateral corners of
mouth upward
(smiling
muscle)
Facial nerve
Risorius
(ri-zor
9
e-us)
(
risor
5
laughter)
Slender muscle inferior and
lateral to zygomaticus
O—lateral fascia
associated with masseter
muscle
I—skin at angle of mouth
Draws corner of lip
laterally
; tenses lips;
synergist of zygomaticus
Facial nerve
Levator labii superioris
(le
˘
- va
9
tor la
9
be-i
soo-per
0
e-or
9
is)
(
leva
5
raise;
labi
5
lip;
superior
5
above, over)
Thin muscle between
orbicularis oris and inferior
eye margin
O—zygomatic bone and
infraorbital margin of
maxilla
I—skin and muscle of
upper lip
Opens lips
; raises and
furrows upper lip
Facial nerve
Depressor labii inferioris
(de-pres
9
or la
9
be-i
in-fer
0
e-or
9
is)
(
depressor
5
depresses;
infer
5
below)
Small muscle running from
mandible to lower lip
O—body of mandible
lateral to its midline
I—skin and muscle of
lower lip
Draws lower lip inferiorly
(as in a pout)
Facial nerve
Depressor anguli oris
(ang
9
gu-li or-is)
(
angul
5
angle, corner;
or
5
mouth)
Small muscle lateral to
depressor labii inferioris
O—body of mandible
below incisors
I—skin and muscle at
angle of mouth below
insertion of zygomaticus
Draws corners of mouth
down and laterally
(a
“tragedy mask” grimace);
zygomaticus antagonist
Facial nerve
Orbicularis oris
Complicated, multilayered
muscle of the lips with
fibers that run in many
different directions; most
run circularly
O—arises indirectly from
maxilla and mandible;
fibers blend with fibers
of other facial muscles
associated with the lips
I—encircles mouth;
inserts into muscle and
skin at angles of mouth
Closes lips
; purses and
protrudes lips; kissing and
whistling muscle
Facial nerve
Mentalis
(men-ta
9
lis)
(
ment
5
chin)
One of the muscle pair
forming a V-shaped muscle
mass on chin
O—mandible below
incisors
I—skin of chin
Wrinkles chin
; protrudes
lower lip
Facial nerve
Buccinator
(bu
9
sı˘-na
0
ter)
(
bucc
5
cheek or
“trumpeter”)
Thin, horizontal cheek
muscle; principal muscle of
cheek; deep to masseter
(see also Figure 10.8)
O—molar region of
maxilla and mandible
I—orbicularis oris
Compresses cheek
(as in
whistling and sucking);
trampoline-like action
holds food between teeth
during chewing; draws
corner of mouth laterally;
well developed in nursing
infants
Facial nerve
Platysma
(plah-tiz
9
mah)
(
platy
5
broad, flat)
Unpaired, thin, sheetlike
superficial neck muscle;
not strictly a head muscle,
but plays a role in facial
expression
O—fascia of chest (over
pectoral muscles and
deltoid)
I—lower margin of
mandible, and skin and
muscle at corner of mouth
Tenses skin of neck
(as
during shaving); helps
depress mandible; pulls
lower lip back and down,
producing downward sag
of mouth
Facial nerve
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