DIFFERENT MANDIBULAR MOVEMENTS

INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
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INTRODUCTION

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The masticatory system is extremely complex. It is made up of
bones, muscles, ligaments and teeth. Mov...
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TMJ ANATOMY

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Condyles articulate with temporal bone and are
located in elliptical concave depression called the
glen...
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MUSCLES FOR MANDIBULAR MOVEMENT
The muscles involved in mandibular movements are
muscles of mastication, and supr...
Temporal muscle, elevation of
mandible

www.indiandentalacademy.com
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2) Masseter
This muscle is rectangular.
Origin
Zygomatic arch and Coronoid process.
Insertion
on the lat...
Masseter muscle, elevation of
mandible

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3) Medial pterygoid
muscle
Origin
Pterygoid fossa
Insertion
Medial surface of the angle of mandible an...
Medial pterygoid muscle

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4) Lateral pterygoid
 Origin
 Two origins
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One head of muscle originates in the outer surface of lateral
pterygoid plat...
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The pterygoid muscle appears to be concerned with all
degrees of protraction and opening movements of
mandible.
It i...
Lateral pterygoid muscle, protrusion
of mandible

www.indiandentalacademy.com
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Muscles of depression

There are three groups of muscles that act to depress
mandible.
 Suprahyoid
1. Diagastric
2. Ge...
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LIGAMENTS OF TEMPOROMANDIBULAR
JOINT
Lateral ligament of TMJ : limit amount of rotation
of mandible and protrac...
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MANDIBULAR MOVEMENTS
Mandibular movement occurs as a complex series of
interrelated three dimensional rota...
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1.Horizontal axis of
movement : is an
opening and closing
motion. It is referred as
hinge movement,and the
horizontal a...
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2.Vertical axis of
rotation: one condyle
moves anteriorly out
of the terminal hinge
position with the
vertical axis of
...
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3. Sagittal axis of
rotation: one condyle
moves inferiorly while
other remains in
terminal hinge
position.

www.indiand...
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Translational movement
This movement is defined as movement in which
every point of moving object has simultaneous...
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Border movement
The maximum amount of movement in any plane
or direction is termed the border movement. Within the...
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Physiologic rest position
The position assumed by mandible when the head
is in an upright position, the muscles ar...
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Centric mandibular movements
Centric relation
Centric relation is the most posterior position of
the man...
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Eccentric mandibular movements
Any relation of the mandible to the maxilla other
than centric relation is a...
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. When the protrusive condylar path projected on to the
sagittal plane, it is called sagittal protrusive condylar...
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Lateral movement
Lateral movement of mandible occurs when one
condyle rotates within TM fossa and the other...
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Opening and closing movements
On opening, the mandible rotates around a horizontal
axis of rotation which p...
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During lateral movement working condyle rotates and
moves slightly outward. This movement is between 2-4
mm.
Fu...
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Parafunctional mandibular movements

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Parafunctional movements of the mandible are
activities that serve no useful fu...
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CONCLUSION
The mandibular movement is considered as
the chewing apparatus of masticatory system. It
should be kept in...
www.indiandentalacademy.com
Leader in continuing dental education

www.indiandentalacademy.com
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  • Temporalis muscle
  • Different mandibular movements /certified fixed orthodontic courses by Indian dental academy

    1. 1. DIFFERENT MANDIBULAR MOVEMENTS INDIAN DENTAL ACADEMY Leader in continuing dental education www.indiandentalacademy.com www.indiandentalacademy.com
    2. 2.  INTRODUCTION  The masticatory system is extremely complex. It is made up of bones, muscles, ligaments and teeth. Movement of mandible is regulated by neurologic controlling mechanism Mandible performs habitual movements, border movements, opening movements, closing movements, protrusive and lateral movements. The main influences on normal jaw movements are the teeth the joints and the surrounding muscle and ligaments.   A basic knowledge of masticatory system starts with temporomandibular joint, since it is the centre of structural and functional interrelationships.  www.indiandentalacademy.com
    3. 3.  TMJ ANATOMY  Condyles articulate with temporal bone and are located in elliptical concave depression called the glenoid fossa in which they travel forward, from side to side. Between the dome shaped concavities in the temporal bones and the condyles are interposed the interarticular fibrocartilage, the meniscus, which are attached at their margins in the articular capsule. The meniscus divides the joints into upper and lower compartment is chiefly a gliding motion. The movement in lower compartment is hinge like. The directional movements of the mandible are results of combined action occurring simultaneously in both fossa. www.indiandentalacademy.com
    4. 4.     MUSCLES FOR MANDIBULAR MOVEMENT The muscles involved in mandibular movements are muscles of mastication, and suprahyoid muscles. 1)Temporalis Origin From temporal fossa, excluding the zygomatic bone.     Insertion Coronoid process and along the anterior border of ascending ramus of mandible. Action Normally, the anterior fibers may contract shortly before the rest of the fibers contract when elevation of mandible begun. The posterior fibers of one side are active in abductive mandibular movements of the same side, but bilateral retraction of the mandible from a protruded position involves all fibers of www.indiandentalacademy.com
    5. 5. Temporal muscle, elevation of mandible www.indiandentalacademy.com
    6. 6.         2) Masseter This muscle is rectangular. Origin Zygomatic arch and Coronoid process. Insertion on the lateral surface of mandibular to the lower one third of the posterior lateral surface of ramus of the mandible and Coronoid process. Action Mandibular elevation is principle function. Although, it may assist in simple protraction and plays a dominant role in elevation if the mandibular is being protracted. www.indiandentalacademy.com
    7. 7. Masseter muscle, elevation of mandible www.indiandentalacademy.com
    8. 8.          3) Medial pterygoid muscle Origin Pterygoid fossa Insertion Medial surface of the angle of mandible and adjoining part of the ramus of mandible. Action Elevation and lateral position of mandible In protrusion of mandible www.indiandentalacademy.com
    9. 9. Medial pterygoid muscle www.indiandentalacademy.com
    10. 10. 4) Lateral pterygoid  Origin  Two origins  One head of muscle originates in the outer surface of lateral pterygoid plate while a smaller and upper head originates from greater sphenoid wing.  Insertion  Anterior surface of neck of condyle. Also some fibers inserted into the capsule of join and to the anterior aspect of articular  The pterygoid muscle appears to be concerned with all degrees of protraction and opening movements of mandible.  It is also active during lateral movements but is assisted by the masseter, med pterygoid and anterior posterior parts of temporal muscle.  Action  Protraction of condyle and at the same time drawing the disc forward. www.indiandentalacademy.com
    11. 11.   The pterygoid muscle appears to be concerned with all degrees of protraction and opening movements of mandible. It is also active during lateral movements but is assisted by the masseter, med pterygoid and anterior posterior parts of temporal muscle www.indiandentalacademy.com
    12. 12. Lateral pterygoid muscle, protrusion of mandible www.indiandentalacademy.com
    13. 13.  Muscles of depression There are three groups of muscles that act to depress mandible.  Suprahyoid 1. Diagastric 2. Genyohyoid 3. Mylohyoid 4. Stylohyoid  Platisma act as a group and are primary movers in opening of mandible.  Infrahyoid – act to stabilize hyoid bone so the suprahyoid group can be effective.  The third group i.e. lateral pterygoid pull the condyles forward or medial ward as the other group act.  www.indiandentalacademy.com
    14. 14.     LIGAMENTS OF TEMPOROMANDIBULAR JOINT Lateral ligament of TMJ : limit amount of rotation of mandible and protract retrodiscal pad from posterior movement of condyle. Sphenomandibular ligament :limit separation between condylar process and the disc. Stylomandibular ligament: limit separation between condylar process and the disc as well as limit protrusive movements of mandible. www.indiandentalacademy.com
    15. 15.       MANDIBULAR MOVEMENTS Mandibular movement occurs as a complex series of interrelated three dimensional rotation and transitional activities. It is determined by combined and simultaneous activities of both temporomandibular joints Two types of movement occur in the TMJ. 1)Rotational movement 2)Translational movement Rotational movement Movement of body about its axis is called as rotation. Rotation occurs when mouth opens and closes around a fixed point or axis within the condyles. Rotational movement occurs in inferior joint cavity, between the superior surface of the condyle and the interior surface articular disc. Rotational movement of mandible www.indiandentalacademy.com occurs in all three reference planes.
    16. 16.  1.Horizontal axis of movement : is an opening and closing motion. It is referred as hinge movement,and the horizontal axis around which it occure is called as hinge axis www.indiandentalacademy.com
    17. 17.  2.Vertical axis of rotation: one condyle moves anteriorly out of the terminal hinge position with the vertical axis of opposite condyle remaining in the terminal hinge position. www.indiandentalacademy.com
    18. 18.  3. Sagittal axis of rotation: one condyle moves inferiorly while other remains in terminal hinge position. www.indiandentalacademy.com
    19. 19.    Translational movement This movement is defined as movement in which every point of moving object has simultaneously the same velocity and direction. If occurs when the mandible brought forward during protrusion. The teeth condyles and the rami all move in same direction and to the same degree. Translation occurs in the superior joint cavity between the superior surface of the articular disc and the mandibular fossa. www.indiandentalacademy.com
    20. 20.    Border movement The maximum amount of movement in any plane or direction is termed the border movement. Within the confines of the border movements there is an extremely wide range of movement called intraborder movement. Most mandibular movement occurs as intraborder movements. Function at the border limits is usually demonstrated during parafunctional activities such as bruxism or wide opening yawning Border movement demonstrates the movement from centric occlusion backward to centric relation and forward to protrusive border movement. The lowermost point in the point of maximum opening from where the mandible can be taken to all border movements www.indiandentalacademy.com
    21. 21.    Physiologic rest position The position assumed by mandible when the head is in an upright position, the muscles are in equilibrium in tonic contraction and condyles are in a unstrained neutral position is the physiologic rest position of mandible. The jaws are not clamped together but, they are separated by rather constant distance, the muscles are not in active function, a limited number of fibers are apparently still contracting to maintain the relaxed position of the mandible and posture of the head www.indiandentalacademy.com
    22. 22.        Centric mandibular movements Centric relation Centric relation is the most posterior position of the mandible relative to the maxilla at the established vertical dimension. Centric relation is not a resting or postural position of the mandible. Contraction of muscles is necessary to move and fix the mandible in it Centric occlusion Centric occlusion is relation of opposing occlusal surfaces that provides maximum intercuspation or planned contact Once centric relarion is established centric occlusion can be built to coincide with it or to provide a broad area of tooth contact in this position. www.indiandentalacademy.com
    23. 23.        Eccentric mandibular movements Any relation of the mandible to the maxilla other than centric relation is an eccentric relation. Eccentric mandibular movements are protrusive and lateral movements Protrusive movement Protrusive relation is the relation of the mandible to the maxilla when the mandible is thrust forward. The mandible translate in forward and downward direction during protrusive movement. The orbit produced by centers of right and left condyles during protrusive movements is referred as protrusive condylar path www.indiandentalacademy.com
    24. 24.    . When the protrusive condylar path projected on to the sagittal plane, it is called sagittal protrusive condylar path The muscles responsible for a straight protrusive movement are external pterygoid muscles acting simultaneously. During protrusive movements, the mandibular anterior teeth protrude forward and downward, disocluding the posterior teeth. The orbit of the incisal point from maximum intercuspation to edge to edge occlusion is referred to as protrusive incisal path. www.indiandentalacademy.com
    25. 25.       Lateral movement Lateral movement of mandible occurs when one condyle rotates within TM fossa and the other condyle translates forward and inward. The translating condyle is called the non-working condyle and the rotating condyle is called the working condyle. The lateral movement from occlusal position and back again is asymmetric. This movement is mainly turn to one side and only a very slight bodily lateral translation of entire mandible. The direction of lateral movements is determined by external – pterygoid muscle on the non-working side and by deep capsular ligaments of the condyle on working side. www.indiandentalacademy.com
    26. 26.       Opening and closing movements On opening, the mandible rotates around a horizontal axis of rotation which passes approximately through the centers of two condyles. Retruded opening and closing With effort and patience the mandible can be pulled back and made to rotate about an axis through the condyles which is rotational and involves no translation. Bennett movement Bennett in 1908 studied the working condylar path and called it ‘Bennett movement’ now referred to as laterotrusion. Bennett movement is a bodily side shift of mandible that occurs during lateral movement. www.indiandentalacademy.com
    27. 27.     During lateral movement working condyle rotates and moves slightly outward. This movement is between 2-4 mm. Functional movements Functional mandibular movement included all natural and characteristic movement occurring during mastication, swallowing, speech and respiration. Much of the functional movements of the mandible take place inside the physiologic limits established by teeth, TMJ, muscles and ligaments. Among the functions of masticatory system swallowing and respiration are innate where as chewing and speech are learned. www.indiandentalacademy.com
    28. 28.  Parafunctional mandibular movements  Parafunctional movements of the mandible are activities that serve no useful function and are potentially harmful to the dentition and its contagious structures. They can result in tooth mobility, migration, excessive wear or fracture, PDL widening. TMJ pain, muscle pain, restricted mandibular movements. ex. Bruxism Normal person masticate with chewing strokes that are well rounded, within definite borders, and less repeated. In bruxism the strokes are much shorter and slower and have an irregular but repeatable pathway appear to relate to the altered functional movement of the condyle which the disorder is centered.    www.indiandentalacademy.com
    29. 29.   CONCLUSION The mandibular movement is considered as the chewing apparatus of masticatory system. It should be kept in mind that mandibular movements occurs besides mastication like in the digestive and respiratory acts, vocal performances and more or less every day human activities behaviors. www.indiandentalacademy.com
    30. 30. www.indiandentalacademy.com Leader in continuing dental education www.indiandentalacademy.com

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