Muscles Of Facial Expression (Module Iv)

Front 1

Occiptofrontalis

Back 1

• The occipitofrontalis is a flat digastric
muscle, with occipital and frontal bellies
that share a common tendon, the
epicranial aponeurosis
• The occipital belly attaches to the superior
nuchal line
• The frontal belly inserts into the skin and
subcutaneous tissue of eyebrows and
forehaad
• Action: Independent contraction of the occipital belly retracts the scalp and contraction of the frontal belly protracts it
• Innervation:
– Occipital belly: Posterior auricular branch of facial nerve
– Frontal belly: Temporal branches of facial nerve

Front 2

Orbicularis Oris

Back 2

• The orbicularis oris, encircles the mouth within the lips, controlling entry and exit through the oral fissure
• The orbicularis oris is also important during articulation (speech)
• Attachments:
– Medial maxilla and mandible, and angle of mouth
– Inserts within the mucous membrane of the lips
• Action:
– Tonic: closes mouth
– Phasic: compresses and protrudes lips
• Innervation:
– Buccal and marginal mandibular branches of facial nerve

Front 3

Buccinator

Back 3

• The buccinator is a thin, flat, rectangular muscle that attaches laterally to the alveolar processes of the maxillae and mandible, opposite the molar teeth, and to the pterygomandibular raphe, a tendinous thickening of the buccopharyngeal fascia. Anteriorly, its fibers blend with the orbicularis oris muscle fibers.
• It occupies a deeper, more medially placed plane than the other facial muscles, passing deep to the mandible
so that it is more closely related to the buccal mucosa than the skin of the face.
•Innervation: buccal branch of facial nerve
• The buccinator, active in smiling, also keeps the cheek taut, thereby preventing it from folding and being injured during chewing.

Front 4

Platysma

Back 4

• Attachments:
– Subcutaneous tissue of supra and infraclavicular regions
– Base of mandible, skin of cheek, angle of mouth and orbicularis oris
• Action
– From superior attachment, tenses the skin, producing vertical skin ridges
– From inferior attachment, helps depress the mandible and draw the corners of the mouth
inferiorly, as in a grimace.
• Innervation:
– Cervical branch of facial nerve

Front 5

Levator anguli oris

Back 5

• The levator anguli oris muscle originates from the
canine fossa of the maxilla immediately inferior to the
infraorbital foramen.
• It inserts into the angle of the mouth, blending with
fibers of the orbicularis oris muscle.
• Action: Lifts the angles of the mouth.
• Innervation: Buccal br. of facial nerve

Front 6

Depressor anguli oris

Back 6

• The depressor anguli oris is a triangular muscle
• It originates from the external oblique line of the mandible.
• The ascending fibers converge
at the apex to insert into the angle of the mouth from below and blend with the fibers of the orbicularis oris muscle.
• Action: Pulls the angles of the mouth downward
• Innervation: Marginal mandibular branch of facial nerve

Front 7

Zygomaticus major

Back 7

• The zygomaticus major muscle arises from the lateral aspect of the zygomatic bone.
• Its fibers angle downward and medially to insert into the angle of the mouth and blend with the orbicularis oris muscle.
• Action: draws the angle of the mouth upward and backward.
• Innervation: Buccal branch of facial nerve (+ some fibers from zygomatic branch)

Front 8

Zygomaticus minor

Back 8

• The zygomaticus major muscle arises from the
anterior aspect of the zygomatic bone.
• Its fibers angle downward and medially to insert into
the skin of the upper lip
• Action: Assists in elevation of the the upper lip
• Innervation: Buccal branch of facial nerve

Front 9

Risorius

Back 9

• The risorius muscle is a thin muscle that arises from parotid and masseteric fascia, and buccal skin
• The risorius muscle inserts transversely into the angle of the mouth
• Action: Retracts the angle of the mouth posteriorly
• Innervation: Mandibular and/or Buccal br. of facial nerve (highly variable)

Front 10

Levator labii superioris

Back 10

The levator labii superioris muscle arises originates from the inferior orbital margin.
• It inserts into the upper lip
• Action: Raise the upper lip.
• Innervation: Buccal br. of facial nerve

Front 11

Depressor labii inferioris

Back 11

• The depressor labii inferioris muscle arises from the lowest portion of the oblique line of the mandible
• It inserts into the skin of the lower lip
• Action: Depresses the lower lip
• Innervation: marginal mandibular br. of facial nerve

Front 12

Orbicularis oculi (Eye)

Back 12

• Originates from medial orbital margin and lacrimal bone
• Inserts into skin around orbit
• Two parts with different
actions:
– Palpebral (blinking)
– Orbital (forceful closing) Palpebral portion Orbital portion
• Innervation: temporal and zygomatic branches of facial nerve

Front 13

Corrugator Supercilli (Forehead)

Back 13

• Attachments
– Medial end of supercilliary arch (ridge superior to the supraorbital margin)
– Skin overlying the supercilliary arch and supraorbital margin
• Action: Draws eyebrows medially and inferiorly
• Innervation: Temporal br. of facial nerve

Front 14

Mentalis (Chin)

Back 14

• Attachments:
– Body of mandible anterior to the roots of inferior incisors
– Skin of chin
• Action:
– Elevates and protrudes lower lip
• Innervation:
– Marginal mandibular br. of facial nerve

Front 15

Nasal muscles: Levvator labi superioris alaeque nasii and alar part of nasalis

Back 15

– Attachments:
• Frontal process of maxilla
• Alar cartilage
– Action
• Depresses ala laterally (dilates nasal aperture)
– Innervation: Buccal br. of facial nerve

Front 16

Nasal Muslces: Procerus and transverse part
of nasalis

Back 16

– Attachments:
• Fascia on dorsum of nose and lateral nasal cartilage
• Skin of inferior forehead between brows
– Action
• Depresses medial end of brow, wrinkles skin on dormsum of nose
– Innervation: Buccal br. of facial nerve