muscles of facial expressions

1. Umar Mohamed

2. Introduction.Introduction.
EmbryologyEmbryology
AnatomyAnatomy
PhysiologyPhysiology
Methods to study muscles.Methods to study muscles.
The three “M” s :muscle ,malformation ,and malocclusionThe three “M” s :muscle ,malformation ,and malocclusion
Muscle as etiology of malocclusionMuscle as etiology of malocclusion
““The equilibrium theory”The equilibrium theory”
Muscles and its treatment modalities.Muscles and its treatment modalities.
conclusionconclusion

3. •Occlusal
Skeletal
Muscular
•The muscle tone, facial expression & orofacial habits mirror
the individuals psychoemotional status.

6. • Orbital group:Orbital group:
Orbicularis Oculi, Corrugator Supercilli
• Nasal group:Nasal group:
Nasalis, Depressor Septii, Procerus
• Oral Group:Oral Group:
Orbicularis Oris, Buccinator, Upper Group of Oral
Muscles, Lower Group of Muscles
• Other Muscle Groups:Other Muscle Groups:
Platysma, Auricular Muscles, Occipito-frontalis.

7.  These are the muscle slips which control the
shape of buccal orifice and the posture of the
lips
They include: the retractors and elevators of the
upper lip viz:-
1. levator labii superioris
2. the zygomaticus major
3. the zygomaticus minor
4. risorius
5. levator anguli oris

8. the depressor and retractors of the lower lip viz:-the depressor and retractors of the lower lip viz:-
1. depressor labii inferioris
2. depressor anguli oris
3. mentalis

10. • Orbital part:
• Origin : Medial PalpebralMedial Palpebral
Ligament and adjoining boneLigament and adjoining bone
• Insertion : Loops return toLoops return to
originorigin
• Action : Throws skin aroundThrows skin around
orbit into folds to protectorbit into folds to protect
eyeball.eyeball.
• Palpebral part:
• Origin :Medial PalpebralMedial Palpebral
LigamentLigament
• Insertion :Lateral PalpebralLateral Palpebral
RapheRaphe
• Action : Closes eyelids and: Closes eyelids and
dilates lacrimal sacdilates lacrimal sac
• Lacrimal part:
• Deep and medial in position.Deep and medial in position.
• Attaches to bone posterior toAttaches to bone posterior to
the Lacrimal sacthe Lacrimal sac

11. • Origin : Medial end of
Supercilliary Arches
• Insertion : Skin of medial half
of eyebrow
• Nerve supply : Zygomatic
Branch of Facial nerve
• Action : Draws eyebrow
medially and inferiorlyq
qq 11

13. • Transverse part:
(Compressor Nasi)
• Origin : Frontal process of
Maxilla
• Insertion : Aponeurosis
across the bridge of Nose
• Action : Compresses the
Nares
• Alar part: (Dilator Naris)
• Origin : Maxilla
• Insertion : Alar cartilage
• Action : Widens Nares
• Nerve supply
:Zygomatic branch of
Facial Nerve

14. • Origin : Nasal bone and the
upper part of the lateral nasal
cartilage
• Insertion : skin over lower
part of the forhead between
eyebrows.
• Nerve supply : Zygomatic
branch of Facial Nerve
• Action : Draws medial border
of the eyebrows downwards.

15. • Origin : Maxilla
• Insertion : Lower part of the
Nasal Septum
• Nerve supply : Buccal
branch of Facial Nerve
• Action : Pulls the nose
inferiorly.

16. • Distinguishing point between nasal and oral breathers.
• Mouth breathers will have disuse atrophy of flaring
muscles of nose.

18. • Origin : Maxilla and Mandible
near midline
• Insertion : Encircles oral
orifice
• Nerve supply :Buccal
branch of Facial Nerve
• Action : Narrows the mouth
and closes lips.

19. • Origin : Posterior part
of Maxilla and Mandible,
Pterygomandibular Raphe
• Insertion : Lip
blending with fibres of
Orbicularis Oris
• Nerve supply :
Buccal branch of Facial
Nerve
• Action : Compresses
cheeks and lips against
teeth

20. • Origin : Parotid fascia and
buccal skin
• Insertion : Corner of the
mouth
• Nerve supply : Buccal
branch of Facial Nerve
• Action : Pulls the corner of
the mouth laterally and
upwards.

21. • Origin : Posterior part of
Lateral surface of the
Zygomatic bone
• Insertion : Skin at the
corner of the mouth
• Nerve supply : Buccal
branch of Facial N.
• Action : Raises the corner of
the mouth and move it laterally.

22. • Origin : Anterior to the
origin of Zygomaticus major
• Insertion : Upper lip medial
to the corner of the mouth.
• Nerve supply : Buccal
branch of Facial N.
• Action : Raises the corner of
the mouth and move it laterally.
(bilaterally smile, unilaterally
sneer)

23. • Origin : Maxilla just superior
to Infraorbital foramen
• Insertion : skin of the upper
lip
• Nerve supply : Buccal
branch of Facial Nerve
• Action : Deepens Nasolabial
sulcus

24. • Origin : Maxilla next to
nose
• Insertion : Alar cartilage
of nose and Skin of the
upper lip
• Nerve supply : Buccal
branch of Facial Nerve
• Action : Flares nostrils
along with dilator naris

25. • Origin : Maxilla just inferior
to the Infraorbital foramen
• Insertion : Skin at the
corner of the mouth
• Nerve supply : Buccal
branch of Facial Nerve
• Action : Elevates the corner
of the mouth.

26. • Origin : Side of the
Mandible
• Insertion : Skin and upper
part of Orbicularis Oris near
the corner of the mouth
• Nerve supply : Marginal
Mandibular branch of Facial
Nerve
• Action : Depresses the
corner of the mouth

27. • Origin : Platysma and
Anterolateral body of
mandible
• Insertion : Skin of the
lower lip
• Nerve supply :
Marginal Mandibular
branch of Facial Nerve
• Action : Depresses the
lower lip and moves it
laterally.

28. • Origin : Mandible just
inferior to the incisor teeth
• Insertion : Skin of the
chin
• Nerve supply :
Marginal Mandibular
branch of Facial Nerve
• Action : Raises and
protrudes lower lip as it
wrinkles the skin of the
chin.

30. The superficial and the lateral cervical muscles:-
 These include viz:-
1. The platysma
2. The trapezius
3. The sterocleidomastoid muscles

31. • Frontalis- normal horizontal wrinkles of the
forehead.
• Corrugator supercilli- frowning & making vertical
wrinkles of the forehead.
• Orbicularis oculi- tight closure of the eyes.
• Orbicularis oris- whistling & pursing the mouth.
• Buccinator- puffing the mouth & then blowing
forcibly
• Platysma- forcible pulling of the angles of the
mouth downwards & backwards forming
prominent vertical folds of the skin on the side of
the neck. The platysma contracts along with the
risorius.

32.  The primary function is expression of the
emotions.emotions.
 The facial muscles are capable of
performing 7000 expressions7000 expressions according to
Coleman.
 -ParesisParesis of the orbicularis oculiorbicularis oculi leads to
the droopingdrooping of the lower eyelid.
-ParalysisParalysis of the orbicularis orisorbicularis oris will lead
to angular cheliosis and the drooling.drooling.

33. The facial muscle also contributes to
stabilizationstabilization of the mandiblemandible during the
infantile swallowing and chewing and
swallowing in the occlusally compromised
adults.
They are also responsible for the
maintenance of the postureposture of the facial
structures.

34. The buccinator mechanism

35. The buccinator mechanism
The tongue pressure opposes the
buccinator mech.

37. • The Commisure smile:-
It is seen in 67% of the population.
It forms a Cupid’s bow.
The corners of the mouth turn upward
because of the pull of zygomaticus major.

38. • It is seen in 31% of the population.
• Upper lip is elevated uniformly
without corners of the mouth turning
upwards.

39. • The upper lip moves superiorly as in
the
• Canine smile ,but lower lip also
moves inferiorly in similar fashion.

41.  Tension: - two types
1. Active
2. Passive

42. Active tension:Active tension: - the tension resulting from the contraction
of the muscle tissue
e.g:-stretch reflex,
it can be also increased by willed contraction of muscles
as in volitional clenching of the teeth.
Passive tensionPassive tension:: - tension which results from the physical
properties (viscoelastic) alone of the tissues is called
passive tension.
e.g:- in facial muscles
In many muscles the elongation will increase both active as
well as the passive tension.
The sum of both the tension is called as the total tension.

43. • Electromygraphy provides a more objective and
definitive means of appraising muscle activity
before, during and after orthodontic therapy.

44. The measurementmeasurement can be done by measuring either the
heightheight of the action potential or the frequencyfrequency of the
individual action potential.
MoyersMoyers was the first one to study the orofacial muscles
using the EMG.

45. Significance:
In orthodontics this can be used in the pre, mid and post
to analyze the appraisal of the muscle activity.
Study by Lowe and Johnston

48. • Summary
• A change in muscle function can be initiate
morphologic variation in the normal
configuration of the teeth and supporting bone.
• The structural abnormality is increased by
compensatory muscle activity to extend that a
balance is reached between pattern,
environment and physiology

49. • Orthodontic therapy in such a manner that the finished
result reflect structural balance between the structural
changes obtained and the functional force acting on the
teeth and investing tissue .

50. Equilibrium theory
.The duration of aduration of a forceforce, be cause o f the bio lo g ic
re spo nse is m o re im po rtant than its m ag nitude .
.

51. Second contributor to the equilibrium that governs the
tooth position is pressure from the lips, cheeks and
tongue. These pressures are much lighter from the
masticatory forces but are greater in duration. Studies
have proved that even the light force can produce tooth
movement if the duration is long. the duration threshold isduration threshold is
6 hours6 hours.. Since the pressure from the lips, cheeks and the
tongue is maintained most of the time there is indeed
tooth movement in conditions when there is loss of
equilibrium.

52. In cases with the orthodontic appliances for e.g.
If arch expansion plate is given, and after certain
time, the lips and cheeks pressure tends to
increase,but there will be balance of forces until
the plate is there. once that is removed there is
unbalance and the teeth would collapse lingually
until a new position of balance is achieved.
 With a habit for e.g. Thumb sucking. If habit like
these creates pressure for more than 6hrs than
teeth will move but if more force is applied for
less duration than there will be no effect.

53. • Muscle function is usually normal in cases of class I
malocclusion.
• The teeth are in a state of balance with environmental
forces.
• Class I open bite problems may be attributed to thumb
and finger sucking habits.
• Hyperactive mentalis activity.

54.  Muscle function adapts to thisMuscle function adapts to this
pattern in line with requirementspattern in line with requirements
of mastication, deglutition,of mastication, deglutition,
respiration, n,speechrespiration, n,speech
 These patients have a shortThese patients have a short
hypotonic upper lip. the lower liphypotonic upper lip. the lower lip
cushions against the palatalcushions against the palatal
surface of the upper incisors.surface of the upper incisors.
Causing lip trap.Causing lip trap.
 there is lack of anterior lip sealthere is lack of anterior lip seal
due to short upper lip.due to short upper lip.
This abnormal contraction of the
hyperactive mentalis muscle
increases the proclination of the
upper incisors.

55.  Lip sucking habit may
develop,with lower lip mass
constantly thrust into excessive
overjet
 The lower incisors buckle as
the mandibular segment is
flattened by continously
abnormal mentalis muscle
activity
 The curve of spee increses
With compensatory tongue thrust, lower tongue
position,and increased buccinator activity, the
maxillary arch narrows.

56.  Many clinicians hypothesize that retroclination of
the maxillary central incisors in class II, div 2 is
caused by increased resting lip pressure against
these teeth.

57.  Dominant bone dysplasia, with
adaptive muscle function
 Strong heredity pattern
 Lowerlip redundant n
hypertrophic relatively
functionless . greateractivity
of upperlip
 The space provided fortongue
is greater,,n it lies on the floor
of mouth Maxillary arch
constricted.  Here the anterior and the
posterior temporal muscle are
found to be more active than
that of masseter muscle in the
interocclusal position.

58. • Thumb sucking:-
• Abnormal lip & tongue activity is frequently
associated with the finger habit.
• The upper lip is no longer called upon to engage
in sphinter-like activity in contact with the lower
lip; it remains hypotonic, functionless and
appears retracted or short.
• In an attempt to create lip seal, there is strong
contraction of the orbicularis oris mentalis
complex.

59. • Long face syndrome or the classic adenoid facies.
• Long and narrow face.
• Narrow nose & nasal passage.
• Short & flaccid upper lip
• An expressionless or blank face..

60.  Hyperactive orbicularis oris
activity.
 Simple tongue thrust:-
Abnormal mentalis activity is
seen.
Tongue is thrust forward during
swallowing to help establish an
anterior lip seal.
 Complex tongue thrust:-
Absence of temporal muscle
constriction during swallowing.
Contraction of the circumoral
muscles during swallowing

61. • The lip sucking habit is a compensatory activity that
results from an excessive overjet and the relative
difficulty of closing the lips properly during deglutition.
• The child cushions the lip to lingual portion of the
maxillary incisors.
• The mentalis muscle extends the lower lip upwards.

62. Graber classifies functional orthodontic appliances
broadly into 3 categories
• Group IGroup I:: transmit muscle forces directly to
teeth .e.g:inclined planes,oral screens
• Group IIGroup II :reposition mandible downward n
forward . resultant force created not only to teeth
but also to associated structures.eg:activator n
its modificatiions
• Group IIIGroup III:: major operating area in vestibule
outside dental arches.supportinng bone n teeth
influenced by changing muscle balance
.eg:frankles functional regulator

63. • A modified vestibular screen that is used for
muscular force application or force elimination.
• This can be used in both the maxilla and the
mandible to shield the lips away from the teeth.
They are used in patients exhibiting lower lip
habits such as lip sucking.
In hyperactive mentalis activity.
To augment anchorage.
Denholtz appliance is used in maxillary arch.

64. • As skin ages, the collagen & elastin fibers in the dermis
break down, reducing skin ability to ‘snap back’ from
smiles & other facial expressions.
• Dynamic movements that cause the skin to repeatedly
crease in the same place, such as smiling, will wear
down the underlying tissue in that specific spot, creating
a line that remains after muscle relaxes.

65. • We are in the present Era where we are
moving from Angel’s paradigm which is
occlusion centered to the soft tissue
paradigm, where we cannot afford to
overlook the soft tissues.
• Muscles have to be given its due
importance not only forming a integral
part of your diagnosis but also have a
role to play in your treatment planning,
and not only in the treatment planning
but also the kind of retention being
planned for the patient.

66. • Hand book of ‘orthodontics’- Moyers
• Problems & procedures in Dentofacial orthopaedics –
Vander Linden
• Current controversiesin orthodontics – Birte Melsen
• Facial growth – Enlow
• Dentofacial Orthopedics with Functional Appliances –
Thomas M. Graber, Thomas Rakosi, Alexandre G.
Petrovic.
• Contemporary Orthodontics – Proffit
• Smile Wikipedia – Free Encyclopedia
• Gray’s Anatomy for students by Richard & Drake.
• Principles of Anatomy & Physiology by Tortora &
Grabowski.
• Graber
• en.wikipedia.org/wiki/Bell's_palsy