PHYSIOLOGY OF THE
STOMATOGNATHIC
SYSTEM
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacadem...
INTRODUCTION
 Stomatognathic- of or relating to the jaws
and the mouth :webstar’s medical dictionary
 As a dentist and e...
Functional Osteology
 Bone is one of the hardest tissues of the human body
 But it is most adaptive and responsive to fu...
www.indiandentalacademy.com
Contd.
 Was expresseds by a mechanical mathematical law=
law of orthogonality
 Now it is established that cartilagenous ...
www.indiandentalacademy.com
Beninghoff’s trajectories
 Concluded that trajectories can be demonstrated in the
maxillo-facial area
 Lines pass throug...
 3 main pillars of
trajectories:
 All from the alveolar bones
an endin in the base of the
skull




The canine pillar...
 Mandible
 Absorbs all the stresses
 Thick cortices and more radially arranged
trabecuae
 Stress trajectories
 From b...
 Thick cortical layer at the base rovides esistance to
bending forces
 Trajectories from www.indiandentalacademy.com and...
www.indiandentalacademy.com
myology

www.indiandentalacademy.com
myology
 Property of muscles that are important fr help
in kinetic activity are
 Elasticity= the ability to return to oi...
 Each fibre is either relaxed or in complete
contraction(all or none law)
 The state of the muscle depends on how many
s...
www.indiandentalacademy.com
 The greatest of contraction is seen when the muscle
approximates its resting position
 The strength reuces as the muscl...
 Resting length
 Rather constant
 Permits maintenance o postural relationship

 Reciprocal innervation and
inhibition
...
Buccinator mechanism
 there is strong inter relarionship between bone
an muscle
 Muscles are a potent force-at rest or w...
 The shape and size o the tooth root and the
periodontal spaces also helps in the final
adaptation
 During swallowing an...
www.indiandentalacademy.com
 Even though doubs still
eist about such a
balance o force-we must
admit that aberration of
muscles can an do lead
to
mar...
Mechanism contd.

www.indiandentalacademy.com
Tongue
 Opposing the buccinator mechanismis a very
powerful structure- the tongue
 It has multiple functions
 Most deve...
www.indiandentalacademy.com
Contd.
 Attached only at the posterior end-can perform many
functions
 Abnormal functions cause deformation in the denta...
MUSCLES OF THE TONGUE

INTRINSIC

EXTRINSIC

Superior longitudinal

Genioglossus

Inferior longitudinal

Hyoglossus

...
Muscles of the tongue

www.indiandentalacademy.com
SUPERIOR LONGITUDINAL
MUSCLE
Shortens the tongue & makes the dorsum concave

INFERIOR LONGITIDINAL MUSCLE
Shortens the to...
TRANSVERSE MUSCLE

Makes the tongue narrow & elongated

VERTICAL MUSCLES

Makes the tongue broad & flattened
www.indianden...
jhg

www.indiandentalacademy.com
EXTRINSIC MUSCLES

Genioglossus - Mandible
Hyoglossus

- Hyoid bone

Styloglossus

- Styloid process

Palatoglossus - ...
Hyoglossus

– depresses the tongue

Styloglossus - pulls it upward & backward
Genioglossus – Protrudes the tongue out of t...
TMJ

www.indiandentalacademy.com
 Articulation between the mandibular condyle
and the inferiorsurface of the sqamous portion
of the temporal bone
 Compou...
normally occupies only half of the joint space,
with its posterior attachments filling the
posterior half. The disc and it...
www.indiandentalacademy.com
Head of the condyle is tubular or ellipsoidal
Unique feature of the joint is that there are
actually 2 joint spaces-sepera...
www.indiandentalacademy.com
 Activity only in the lower cavity till the mnible is
opened to the physiological rest position
 After tis even gliding ...
 In the lateral shift/bennet movement the
conyle on the working side rotates nd moves
laterally
 The condyle on the othe...
 Due to overclosures-the isc is move forward
and the conyle rides over the posterior border
of the disc
 Impinges on the...
 The tmj is beautifully engineerd to hanle
multiple tasks endowed to it
 To maintain it-proper occlusal management an
ma...
functional movements of
the mandible
 Mandible ah 13 muscles attached to it
 Due to limitations of morphology and struct...
www.indiandentalacademy.com
Forced retrusion Posterior fibres of the
temporalis,masseter,suprahyoid muscles
opening

lateral pterygoid-main. Supra,inf...
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
www.indiandentalacademy.com
COMPENSATORY MUSCLE FUNCTIONS
 While mastication may call for most potent
effort from the associated muscles, the most
fr...
Positions of the mandible
 basic positions are
 Postural resting position (Physiologic
rest)
 Centric relation
 Initia...
POSTURAL RESTING POSITION













It is one of the earliest posture positions to be
developed. Mandible is ...
CETRIC RELATION
 As far as muscle physiology is concerned,
centric relation may be defined as unstrained,
neutral positio...
INITIAL CONTACT
 As the mandible moves from physiologic rest or
the postural resting position toward occlusion of
teeth, ...
CENTRIC OCCLUSION
 Centric occlusion is a static position
 It is harmonious with the centric relation
 Teeth brought in...
MOST RETRUDED POSITION
(Terminal Hinge Position)
 Reproducible retruded mandibular
position with the teeth in occlusion
...
MOST PROTRUDED
POSITION
 This position is variable from individual to
individual than the detruded position.
 Shows the ...
HABITUAL RESTING POSITION
 There are certain types of malocclusions that
prevent the patient from achieving a physiologic...
HABITUAL OCCLUSAL POSITION
 In normal occlusion the centric occlusion
and habitual occlusion should be the same.
But the ...
Functions of the system
 These are





Deglutition
Mastication
Respiration
Speech

www.indiandentalacademy.com
DEGLUTITION
Infantile swallow ( visceral swallow)

Mature swallow ( somatic swallow)
www.indiandentalacademy.com
INFANTILE (VISCERAL) SWALLOW

www.indiandentalacademy.com
CHARACTERISTICS OF INFANTILE
SWALLOW
The jaws are apart, with the tongue between the
gum pads
The mandible is stabilized...
TRANSITION PERIOD
At about the 5 to 6th month of age, as the

incisors begin to erupt, certain proprioceptive
impulses com...
MATURE ( SOMATIC)
SWALLOW

www.indiandentalacademy.com
CHARACTERISTICS OF
MATURE SWALLOW
The teeth are together
The mandible is stabilized by contraction of the
mandibular ele...
DEGLUTITION CYCLE
FLETCHER gave 4 phases
1.Preparatory swallow
2.Oral phase of swallowing
3.Pharyngeal phase of swallowing...
PREPARATORY SWALLOW
 Starts as soon as liquids
are taken in, or after the
bolus has been
masticated
 The liquid or bolus...
Oral phase of swallowing
 Soft palate moves upward &
the tongue drops downward &
backward
 Larynx & hyoid bone move
upwa...
Pharyngeal phase of
swallowing
 Begins as the bolus passes
through the fauces
 The pharyngeal tube is raised
upward en m...
Esophageal phase of
swallowing
 Commences as the food
passes the
cricopharyngeal
sphincter
 While peristaltic
movement c...
Mastication
 In the infant food is taken by sucklingunlearned or automatic reflex
 Rythmic cving in of the cheeks,bobbin...
Contd.
 Change to solid food-lesser action of the lips
and lesser thrust o the mandiblelteral thrust of
the mandible seen...
Contd.
 3)crushing phase=>starts with high velocity
and slows down as food is crushed
 4)tooth contact=>takes place with...
Respiration
 Inherent reflex activity
 Demand on muscles are more subtle and more difficult
to appreciate
 Posture has ...
Cont.
 All the learned jaw functions are built around
and accomodated to the tongue and
mandibular positions wich ake cle...
Speech









Learned activity –depends on maturation of organism
Makes use of muscles that have other functions...
 F>learned,automatic practical reactionswhistling,playing instrument,humming

Muscles involved
Walls of the torso,the res...
 Normal structure is necessary for production of
sound-in cleft palate cases not possible even
with muscular compensation...
 The lips and the tongue undergo maturational
changes
 Degree of lip protrution varys the length of the
vocal tract
 Wi...
conclusion
 The study of the intra oral and peri oral
structures-their normal morphology and activity
is very important f...
bibliography
 Orthodontics:principles and practicesT.M Graber
 Orthodontics:Graber and Vanarsdal
 Contemporary Orthodon...
www.indiandentalacademy.com
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The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.

Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
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Physiology of the stomatognathic system /certified fixed orthodontic courses by Indian dental academy

  1. 1. PHYSIOLOGY OF THE STOMATOGNATHIC SYSTEM INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
  2. 2. INTRODUCTION  Stomatognathic- of or relating to the jaws and the mouth :webstar’s medical dictionary  As a dentist and especially as an orthodontist,it is essential that we have a sound knowledge of and understand the importance of the stomatognathic system  Until we know what is normal we will not be able to recognise aberrancy www.indiandentalacademy.com
  3. 3. Functional Osteology  Bone is one of the hardest tissues of the human body  But it is most adaptive and responsive to functional forces  Meyer -1864:proposed the trajectory theory of bone formation  >the arrangement of the trabeculae in the spongiosa followed a trajectory pattern  1870:julius wolff>these trabecular arrangement was due to functional forces  Any change in direction or intensity of the forces would change the internal archietecture www.indiandentalacademy.com
  4. 4. www.indiandentalacademy.com
  5. 5. Contd.  Was expresseds by a mechanical mathematical law= law of orthogonality  Now it is established that cartilagenous and membranous bones react differently to forces  Tajectories need not pass at right angles to each other—even their course may be wavy  Increased function increases bone density while decreased function decreases itmuscles have a great influence over bones and may even change their shape  Thus the timed manipulation of the musculature may be beneficial to the orthodontist www.indiandentalacademy.com
  6. 6. www.indiandentalacademy.com
  7. 7. Beninghoff’s trajectories  Concluded that trajectories can be demonstrated in the maxillo-facial area  Lines pass through both the spongy and compact bone  They obey no individual bone margins     Maxilla: Transfers the whole stress to the cranium Has thin cortices that are interconnected by trabeculae Stress trajectory:can be considered as the craniofacial unit www.indiandentalacademy.com
  8. 8.  3 main pillars of trajectories:  All from the alveolar bones an endin in the base of the skull    The canine pillar The zygomatic pillar The pterygoid pillar  Curve around the sinuses,nasal and orbital opening  The supra and infra orbital ridges and the zygomatic buttress reinforce these pillars www.indiandentalacademy.com
  9. 9.  Mandible  Absorbs all the stresses  Thick cortices and more radially arranged trabecuae  Stress trajectories  From beneath the teeth-join together in comman pillar—ends at the condyle  Mandibular canal and nerve are protected-unloading of nerve www.indiandentalacademy.com
  10. 10.  Thick cortical layer at the base rovides esistance to bending forces  Trajectories from www.indiandentalacademy.com and coronoid the symphysis,angle process join this main pillar
  11. 11. www.indiandentalacademy.com
  12. 12. myology www.indiandentalacademy.com
  13. 13. myology  Property of muscles that are important fr help in kinetic activity are  Elasticity= the ability to return to oiginal lemgth and shape after contraction or extension  Normally relaxed muscle withstand only a certain amount of elongation  Contractility=the ability to contract forcefully when stimulated by an action potential  Energy for this is provided by high energy bonds of ATP  Lactic acid accumulation leads to fatigue www.indiandentalacademy.com
  14. 14.  Each fibre is either relaxed or in complete contraction(all or none law)  The state of the muscle depends on how many such fibres are active  Isometric contraction when muscle resists external stress withot shortening-only the tension increases  Isotonic contraction when the tone or tension remains the same but the length decreases www.indiandentalacademy.com
  15. 15. www.indiandentalacademy.com
  16. 16.  The greatest of contraction is seen when the muscle approximates its resting position  The strength reuces as the muscle shortens or lengthens beyond this position  Other principles of muscle physiology  All or none law  Intensity of contraction is independent of the strength of thr action potential as long as the threshold is crossed  Seen only when the muscle is not fatigued  Muscle tonus  State of slight constant tension  Basis of reflex posture www.indiandentalacademy.com
  17. 17.  Resting length  Rather constant  Permits maintenance o postural relationship  Reciprocal innervation and inhibition  Inhibition of contraction may be brought about by excitation of the antagonist  It is through this that movements are coordinated www.indiandentalacademy.com
  18. 18. Buccinator mechanism  there is strong inter relarionship between bone an muscle  Muscles are a potent force-at rest or when active  Teeth and supporting tissues are influenced by the contiguous musculature  The balance between the tongue and the perioral musculature influences the morphology of the dental arches and the teeth www.indiandentalacademy.com
  19. 19.  The shape and size o the tooth root and the periodontal spaces also helps in the final adaptation  During swallowing and mastication- tongue exerts 2-3 times more force than the peri oral muscles  Counter acted by the tonal contraction,atmospheric pressure,peripheral recruitment from the buccal musculature www.indiandentalacademy.com
  20. 20. www.indiandentalacademy.com
  21. 21.  Even though doubs still eist about such a balance o force-we must admit that aberration of muscles can an do lead to markedmalocclusion  The continuous band of muscle that encircle the dentition and attach to the pharyngeal tubercle comprises the buccinator mechanism www.indiandentalacademy.com
  22. 22. Mechanism contd. www.indiandentalacademy.com
  23. 23. Tongue  Opposing the buccinator mechanismis a very powerful structure- the tongue  It has multiple functions  Most developed in a new born  In infancy extrinsic suspensory muscles attach the tongue to the osseous structures  Produces gross movement in the gorizontal direction(suckle-swallow) www.indiandentalacademy.com
  24. 24. www.indiandentalacademy.com
  25. 25. Contd.  Attached only at the posterior end-can perform many functions  Abnormal functions cause deformation in the dental arches  May be caused by either deformed arches or visceral swallow pattern  Leads to proclination o the maxillary incisors,constriction of buccal segment an may create an open bite  Compensating action of mentalis causes retraction of the lower incisors www.indiandentalacademy.com
  26. 26. MUSCLES OF THE TONGUE INTRINSIC EXTRINSIC Superior longitudinal Genioglossus Inferior longitudinal Hyoglossus Transverse Styloglossus Vertical Palatoglossus www.indiandentalacademy.com
  27. 27. Muscles of the tongue www.indiandentalacademy.com
  28. 28. SUPERIOR LONGITUDINAL MUSCLE Shortens the tongue & makes the dorsum concave INFERIOR LONGITIDINAL MUSCLE Shortens the tongue & makes the dorsum convex www.indiandentalacademy.com
  29. 29. TRANSVERSE MUSCLE Makes the tongue narrow & elongated VERTICAL MUSCLES Makes the tongue broad & flattened www.indiandentalacademy.com
  30. 30. jhg www.indiandentalacademy.com
  31. 31. EXTRINSIC MUSCLES Genioglossus - Mandible Hyoglossus - Hyoid bone Styloglossus - Styloid process Palatoglossus - Palate www.indiandentalacademy.com
  32. 32. Hyoglossus – depresses the tongue Styloglossus - pulls it upward & backward Genioglossus – Protrudes the tongue out of the mouth by pulling the posterior part forwards Palatoglossus – brings the palatoglossal arches together, thus shutting the oral cavity from the oropharynx www.indiandentalacademy.com
  33. 33. TMJ www.indiandentalacademy.com
  34. 34.  Articulation between the mandibular condyle and the inferiorsurface of the sqamous portion of the temporal bone  Compound –movable joint  Meniscus-a fibrous connective tissue wafer fills most of the space between the condylar head and the articular fossa and divides the joint cavities into 2 compartments. www.indiandentalacademy.com
  35. 35. normally occupies only half of the joint space, with its posterior attachments filling the posterior half. The disc and its posterior attachments are generally referred to as the soft tissue component of the TMJ. all the above mentioned structures are enclosed with in the capsular ligament It is lined by synovial membrane www.indiandentalacademy.com
  36. 36. www.indiandentalacademy.com
  37. 37. Head of the condyle is tubular or ellipsoidal Unique feature of the joint is that there are actually 2 joint spaces-seperated by the disc Thus the joint is capable of dual funcion Lower cavity—rotary/hinge movement Upper cavity—gliding/translatory movement www.indiandentalacademy.com
  38. 38. www.indiandentalacademy.com
  39. 39.  Activity only in the lower cavity till the mnible is opened to the physiological rest position  After tis even gliding motion takes place  When opened in his manner the articular disc glides over the articular eminence  The condyle rotates against the inferior surface of the disc  Lateral pterygoid helps to move the disc anteriorly www.indiandentalacademy.com
  40. 40.  In the lateral shift/bennet movement the conyle on the working side rotates nd moves laterally  The condyle on the other ide noves forwards and mesially in an arc  There is no muscle which ertracts the discnothig opposite the action of the lateral pterygoid  Posterior limit formed by the squamo-tympanic fissure—medially by the petro-tympanic fissure www.indiandentalacademy.com
  41. 41.  Due to overclosures-the isc is move forward and the conyle rides over the posterior border of the disc  Impinges on the retrodiscal soft tissues-cicking an discomfort to the patient-misdiagnosed as arthritic changespain may be ue to impingment or ue to pterygoid muscle spasm(mpd)  The main reason fo the mpd is neurogenic or psychological www.indiandentalacademy.com
  42. 42.  The tmj is beautifully engineerd to hanle multiple tasks endowed to it  To maintain it-proper occlusal management an mainenance of vertical dimensions is essential www.indiandentalacademy.com
  43. 43. functional movements of the mandible  Mandible ah 13 muscles attached to it  Due to limitations of morphology and structure of the tmj-can be moved only in certain directions  Has postural stability along with primay movements www.indiandentalacademy.com
  44. 44. www.indiandentalacademy.com
  45. 45. Forced retrusion Posterior fibres of the temporalis,masseter,suprahyoid muscles opening lateral pterygoid-main. Supra,infra hyoidgenio,mylo hyoids,digasric>stabilising Temporalis,masseter,medial pter.>controlled relaxation closure Temporalis, masseter >main action medial ptery. >part action Lateral ptery >cntrolled relaxation protrusion Lateral and medial pter. Lateral movement Temporalis + lat. pter www.indiandentalacademy.com
  46. 46. www.indiandentalacademy.com
  47. 47. www.indiandentalacademy.com
  48. 48. www.indiandentalacademy.com
  49. 49. www.indiandentalacademy.com
  50. 50. www.indiandentalacademy.com
  51. 51. COMPENSATORY MUSCLE FUNCTIONS  While mastication may call for most potent effort from the associated muscles, the most frequent demands are made by deglutition, respiration, speech and posture.  At times two or more of these functions are carried on simultaneously.  where there is malocclusion or abnormal morphologic relationship certain compensatory or adaptive muscle functions may arise, either to restrain the dental malocclusion or to actually increase the discrepancy. www.indiandentalacademy.com
  52. 52. Positions of the mandible  basic positions are  Postural resting position (Physiologic rest)  Centric relation  Initial contact  Centric occlusion  Most retruded position (terminal hinge position)  Most protruded position  Habitual resting position www.indiandentalacademy.com  Habitual occlusion position
  53. 53. POSTURAL RESTING POSITION           It is one of the earliest posture positions to be developed. Mandible is suspended from the cranial base by the cradling musculature. Here the jaws are separated by a constant distance. Factors influencing the postural position are the following: Body and head posture Sleep Psychic factors influencing muscle tonus Age Proprioception from the dentition and muscles Occlusal changes such as attrition Pain Muscle disease and muscle spasm and www.indiandentalacademy.com Temporomandibular joint disease.
  54. 54. CETRIC RELATION  As far as muscle physiology is concerned, centric relation may be defined as unstrained, neutral position of the mandible in which the anteriosuperior surfaces of mandibular condyles - in contact with the concavities of the articular disks as they approximate the posteroinferior third of their respective articular eminentia.  This means that the mandible is deviating neither to the right nor to the left and is neither protruded no retruded.  Such a relation can be the same as the postural resting position, the point of initial occlusal contact and centric occlusion. www.indiandentalacademy.com
  55. 55. INITIAL CONTACT  As the mandible moves from physiologic rest or the postural resting position toward occlusion of teeth, if all is normal it maintains a centric relation position as far as the articular fossae are concerned.  If there is normal occlusion the point of initial contact produces no change in the function of temporomandibular joint and all inclined planes are brought together simultaneously in the maxillary and mandibular teeth.  Premature contacts are seen quite frequently, they can initiate deflections in the mandibular path of closure.  This causes traumatic forces to be exerted on the teeth and severe cases will produce www.indiandentalacademy.com temporomandibular joint problems
  56. 56. CENTRIC OCCLUSION  Centric occlusion is a static position  It is harmonious with the centric relation  Teeth brought into contact with unstrained relation of the condyles  Few patients can show centric occlusion  Establishes the occlusal vertical dimension  Not necessarily the maximum intercuspation position www.indiandentalacademy.com
  57. 57. MOST RETRUDED POSITION (Terminal Hinge Position)  Reproducible retruded mandibular position with the teeth in occlusion  Normally starting point in occlusal rehabilitation  Some patients can easily retrude a few mm. while others find it difficult  Mandible should not be guided or forced beyond the unstrained position of the mandible-unbiological-would compress the tissues. www.indiandentalacademy.com
  58. 58. MOST PROTRUDED POSITION  This position is variable from individual to individual than the detruded position.  Shows the range of movement of the mandible  Flacidity of capsular ligament allows ondyle to over ride the anterior margin of the eminence  Condyle locked-muscles tetanisedfatigue www.indiandentalacademy.com
  59. 59. HABITUAL RESTING POSITION  There are certain types of malocclusions that prevent the patient from achieving a physiologic resting position.  Example in class II div 2 malocclusion with maxillary incisors inclined lingually there is a tendency to force the condyles posteriorly and superiorly in the articular fossae  the physiologic resting positions can be changed due to mental disturbances, enlarged adenoids, temporomandibular joint pathology, psychic trauma, selective paralysis by poliomyelitis and confirmed mouth breathing etc. www.indiandentalacademy.com
  60. 60. HABITUAL OCCLUSAL POSITION  In normal occlusion the centric occlusion and habitual occlusion should be the same. But the occlusal relationship can be changed when there is an environmental imbalance induced by improper restoration, tooth loss etc.  It is vitally important that the dentist make sure that the habitual occlusal position and the centric occlusal position are the same  they are in harmony with centric relation and the postural resting position of the mandible. www.indiandentalacademy.com
  61. 61. Functions of the system  These are     Deglutition Mastication Respiration Speech www.indiandentalacademy.com
  62. 62. DEGLUTITION Infantile swallow ( visceral swallow) Mature swallow ( somatic swallow) www.indiandentalacademy.com
  63. 63. INFANTILE (VISCERAL) SWALLOW www.indiandentalacademy.com
  64. 64. CHARACTERISTICS OF INFANTILE SWALLOW The jaws are apart, with the tongue between the gum pads The mandible is stabilized by contraction of the muscles of the 7th cranial nerve & the interposed tongue. The swallow is guided, & to a great extent controlled by sensory interchange between the lips & www.indiandentalacademy.com the tongue.
  65. 65. TRANSITION PERIOD At about the 5 to 6th month of age, as the incisors begin to erupt, certain proprioceptive impulses come into play & the peripheral portions of the tongue starts to spread laterally. An average infant would show a dominant & exclusive thrusting swallow for the first 6 months of life,a transitional thrusting & lateral spread of tongue during the next year & a dominant somatic swallow thereafter. www.indiandentalacademy.com
  66. 66. MATURE ( SOMATIC) SWALLOW www.indiandentalacademy.com
  67. 67. CHARACTERISTICS OF MATURE SWALLOW The teeth are together The mandible is stabilized by contraction of the mandibular elevators,which are primarily 5th cranial nerve muscles The tongue tip is held against the palate, above & behind the incisors There are minimal contractions of the lips during the mature swallow. www.indiandentalacademy.com
  68. 68. DEGLUTITION CYCLE FLETCHER gave 4 phases 1.Preparatory swallow 2.Oral phase of swallowing 3.Pharyngeal phase of swallowing 4.Esophageal phase of swallowing www.indiandentalacademy.com
  69. 69. PREPARATORY SWALLOW  Starts as soon as liquids are taken in, or after the bolus has been masticated  The liquid or bolus is then in a swallowpreparatory position on the dorsum of the tongue.  The oral cavity is sealed by lip & tongue. www.indiandentalacademy.com
  70. 70. Oral phase of swallowing  Soft palate moves upward & the tongue drops downward & backward  Larynx & hyoid bone move upward  Smooth path for the bolus as it is pushed from the oral cavity by the wave like rippling of the tongue  Oral cavity is stabilized by the muscles of mastication, & maintains the anterior & lateral seal www.indiandentalacademy.com
  71. 71. Pharyngeal phase of swallowing  Begins as the bolus passes through the fauces  The pharyngeal tube is raised upward en masse  Nasopharynx is sealed off by closure of the soft palate against the posterior pharyngeal wall  Hyoid bone & base of tongue move forward as the pharynx & tongue continue their peristaltic – like movement of the bolus of the food www.indiandentalacademy.com
  72. 72. Esophageal phase of swallowing  Commences as the food passes the cricopharyngeal sphincter  While peristaltic movement carries the food through the esophagus, the hyoid bone , palate & tongue return to their original positions www.indiandentalacademy.com
  73. 73. Mastication  In the infant food is taken by sucklingunlearned or automatic reflex  Rythmic cving in of the cheeks,bobbing of the hyoid bone,snake like movement of the tongue,anterior movement o the ongue and nodding movement of the head  Mandible is protuded  During deglutition rythmic contractionof the tongue and facial musclesaids in stabilising the mandible www.indiandentalacademy.com
  74. 74. Contd.  Change to solid food-lesser action of the lips and lesser thrust o the mandiblelteral thrust of the mandible seen-more to the working side  6 phases outlined by murphy  1)preparatory phase=>food in mouth-tongue positions it-mandible moves to working side  2)food contact=>characterised by a pauseprobably to determine food consistency www.indiandentalacademy.com
  75. 75. Contd.  3)crushing phase=>starts with high velocity and slows down as food is crushed  4)tooth contact=>takes place with skight change in direction-muscles are already ready for this  5)grinding phase=>transgression of the mandible across the maxillary teeth-most patients chew unilaterally-cyclic event  6)centric occlusion=>mandible back to terminal position-next cycle begins www.indiandentalacademy.com
  76. 76. Respiration  Inherent reflex activity  Demand on muscles are more subtle and more difficult to appreciate  Posture has a significant effect on respiration  Oral musculature is responsible for vital positional relationships-maintains the airway  In the infant-airway maintained by Mandible maintained anteroposteriorly  Stability f the tongue and post. Pharyngeal wall  Axial musculature around the vertebrae www.indiandentalacademy.com
  77. 77. Cont.  All the learned jaw functions are built around and accomodated to the tongue and mandibular positions wich ake clear airway possible  Maintainance of the respiratory spaces and airway is significant in facial growth  Respiration in the chil helps keeping the pharynx patent as well  Important for development of speech as well www.indiandentalacademy.com
  78. 78. Speech         Learned activity –depends on maturation of organism Makes use of muscles that have other functions According to WEST other than speech functions are:: A>innate,automatic,vegetativeswallowin,breathing,gagging etc. B>learned,automatic,vegetative-biting,chewing,sucking C>lerned,automati,emotional-grimaces,mannerisms D>innate,automatic,emotional-laugh,smile.sob E>learned,non automatic,discriminatory,voluntaryexplore with tongue,spreading lips,kissing,blowing www.indiandentalacademy.com
  79. 79.  F>learned,automatic practical reactionswhistling,playing instrument,humming Muscles involved Walls of the torso,the respiratory tract,the pharyx,the soft palate,the tongue,the lips and face and nasal passageways are involvedsimultaneou breathing is necessary to provide vibrations for sound Tongue,lips and velopharyngeal closure www.indiandentalacademy.com moify utgoing stream to produce sound
  80. 80.  Normal structure is necessary for production of sound-in cleft palate cases not possible even with muscular compensation  Speech mechanism changes air direction,flow,release,pressure,general and lingual air path  Any aberrancy may lead to compensatory morphological changes like enlarged adenoids,compressed nares etc. With respect to tongue  In infancy-suckle reflex is active-only extrinsic muscles are well developed-only later the intrinsic muscles capable of speech develope www.indiandentalacademy.com
  81. 81.  The lips and the tongue undergo maturational changes  Degree of lip protrution varys the length of the vocal tract  With the reduction of suckle swallow-delicate movements of the lips are noted. Velopharyngeal closure  Very important for the dentist-in conditions of cleft palate-inadequate valving is seen-even in rehabilitated cases  Upward and backward movement to contact the post pharyngeal wall is important for certain sound production  It is seen that compensatory lip and tongue activity is present to ward over www.indiandentalacademy.com malocclusions.
  82. 82. conclusion  The study of the intra oral and peri oral structures-their normal morphology and activity is very important for us.  Unless we know what is normal it is difficult to recognise and correct abnormalities  Also, the structures are all inter related ::follow scientific principles and order in their development.  It becomes important to follow the functions of the structures which ultimately leads to changes in the morphology.. www.indiandentalacademy.com
  83. 83. bibliography  Orthodontics:principles and practicesT.M Graber  Orthodontics:Graber and Vanarsdal  Contemporary Orthodontics: William.R.Proffit  Handbook Of Facial Growth :Donald.H.Enlow www.indiandentalacademy.com
  84. 84. www.indiandentalacademy.com

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