Ra lecture - muscles of the face

Muscles of Form
and Expression

Introduction
 Muscular action forms prominences,
folds, hollows, grooves, and
furrows.
 Repetition of muscular actions leaves
characteristic signs on the face.
 Gravitational pull has an effect on
features:
 Horizontal position – laterally and
posteriorly
 Vertical position – inferiorly

Introduction (con’t)
 Furrows run vertically on horizontal
muscles and laterally on vertical
muscles
 Origin – where the muscle is attached
to a fixed point
 Insertion – where the muscle is
attached to a movable point

Construction of Muscles
 Muscles are described by the
following:
 Action – levatator palpebrae superioris
 Number of heads/fibers – triceps brachii
 Location – temporalis
 Shape – trapezius
 Origin and insertion – occipitofrontalis

Muscles of the Cranium
 Occipitofrontalis/epicranius (1)
 Origin and insertion
 2 broad bellies separated by an
aponeurosis:
 Occipital belly – quadrilateral in form; draws
the scalp backward
 Frontal belly – quadrilateral muscle slightly
larger that occipitalis; creates transverse
furrows across the forehead
 Auricular muscles (3)
 Effect movement of the ear
 No effect on surface form

Muscles of Mastication
 Temporalis (2)
 Broad and fan-shaped
 Strongest of the chewing muscles
 No effect on surface form
 Masseter (2)
 Thick, quadrilateral muscle located
on the side of the face
 Named for action – chewing
 When contracted, raises lower jaw

Muscles of Mastication (con’t)
 Pterygoideus medialis (2) and
lateralis (2)
 Permit side to side movement of the
lower jaw
 No influence on surface form

Muscles of the Eyelids
 Obicularis oculi (2)
 Round muscle; surrounds eyelids and
portion of cheek
 Lateral angle creates permanent folds –
optic facial sulci – also known as
“crow’s feet”
 Corrugator (2)
 Also known as “the frowning muscle”
 Creates the vertical interciliary sulci

Muscles of the Eyelids (con’t)
 Levator palpebrae superioris (2)
 Elevates the upper eyelid
 Superior palpebrae sulcus located on
the upper eyelid

Muscles of the Nose
 Procerus
 Long, thin muscle over the bridge of the
nose and between the eyes; merges
with frontalis muscle
 Upon contraction, creates transverse
interciliary sulci and pull the medial
ends of the eyebrows downward

Muscles of the Mouth
 Obicularis oris
 Round muscle that encircles the
mouth that also consists of other
facial muscles
 Contraction closes the lips
 As a result of loss of teeth, vertical
sulci form on the mucous
membranes

Muscles of the Mouth
 Quadratus labii superioris
 Consists of :
 levator labii superioris alaeque nasi (2) –
“common elevator”
 levator labii superioris (2) – lateral to
common elevator
 zygomaticus minor (2) – lateral to previous
 Contraction (along with the levator anguli
oris) creates the nasolabial fold

Muscles of the Mouth (con’t)
 Levator anguli oris (2)
 Located in the area of the canine
teeth
 Helps to create the nasolabial fold
and angular oris eminence
 Zygomaticus major
 Lateral to quadratus
 Upon contraction, draws the angle of
the mouth backward and upward
 Also known as “the laughing muscle”

 Buccinator
 Also known as “the trumpeter’s
muscle”
 Located in the soft area of the cheek
 Responsible for vertical furrows
(bucco-facial sulci also known as
dimples)

 Risorius (2)
 Located superficial to the buccinator
 Upon contraction, retracts the corners
of the mouth
 Depressor anguli oris (2)
 Also known as triangularis
 Upon contraction, depresses the
corners of the mouth

 Depressor labii inferioris
 Also known as quadratus
 Upon contraction, pulls the lower lip
down and slightly to the side
 Mentalis (1)
 Wrinkles the chin and
raises/protrudes lower lip
 Superficial to the mental eminence
 May form a dimple in the chin

Muscles of the Neck
 Platysma (2)
 Broad, flat, and superficial
 Upon contraction, lowers the jaw
 Creates transverse furrows; platysmal sulci
 Sternocleidomastoideus (2)
 Measure the widest part of the neck
 Origin – the sternum and the clavicle
 Insertion – the lateral surface of the mastoid
process
 Upon contraction, pulls the head sideways

Muscles of the Neck (con’t)
 Digastricus (2)
Located below the body of the
mandible
Responsible for cords of the neck in
older persons

Ra lecture - muscles of the face

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