Mandibular movements occur around the TMJ which is capable of making complex movements. Temporomandibular joint is the joint connecting your lower jaw and your skull. The movements can be categorized as follows -  Basic movements  Excursive movements  Border movements  Functional movements  Parafunctional movements Factors affecting mandibular movements are –  Condylar path / guidance  Opposing tooth contact and Anterior guidance  Neuromuscular control

1. - Simplified
Dentistry

2. Mandibular movements occur around the TMJ which is capable of making complex movements.

3.  Temporomandibular joint is the joint connecting your lower jaw and your skull.
 The movement of this joint lets you open and close your mouth and chew from side to side.
 It is the articulation between the mandible and the cranium.

4.  Condylar path / guidance
 Opposing tooth contact and Anterior guidance
 Neuromuscular control
Condylar path + Anterior guidance = End Controlling Factors
Posterior
Determinant
Anterior
Determinant
(Fixed factor) (Variable factor)

5. This is the path travelled by the condyle in the TMJs during various mandibular movements.
It is influenced by - Inclination of glenoid fossa
 Tone of muscles responsible for mandibular movements and their nerve controls
 Attached ligaments
 Shape and movements of the articular disc
 Teeth ( when present)

6. The condylar path is not under dentists’ control and cannot be altered.
The movements can be categorized as follows -
 Basic movements
 Excursive movements
 Border movements
 Functional movements
 Parafunctional movements

7. 1. Rotation
2. Translation
All mandibular motion is either Rotation or Translation.
1. Rotation ( Hinge Movement) -
• The action/process of rotating on or as if on an axis/centre.
• Movement is similar to door hinge and the condyle rotates without any bodily movement.
• Occurs in the lower compartment of TMJ.

8. 3 axis -  Horizontal
 Frontal or Vertical
 Sagittal

9. Rotational Movements
Horizontal(Transverse
horizontal)axis
Frontal axis Sagittal axis
During mouth opening and protrusion
and is also a posterior border
movements
During lateral
movements
Axis -
It is a line around which a body may rotate/around which a structure would turn if it could revolve.

10. Horizontal axis of Rotation -
 Mandibular movement around the horizontal axis is an opening and closing motion.
 It is referred to as hinge movement and the horizontal axis around which it occurs is referred to as the
Hinge axis.
 Hinge movement is probably the only example of mandibular activity in which a “pure” rotational
movement occurs.
 In all other movements rotation around an axis is accompanied by translation of the axis.

11. Terminal hinge axis -
 When the condyles are in their superior position in the articular fossae and the mouth is purely
rotated open, the axis around which movement occurs is called the terminal hinge axis.
 Rotational movement around the terminal hinge rarely occurs during normal function.

12. Frontal/Vertical axis of rotation -
 Mandibular movement around the frontal axis occurs when one condyle moves anteriorly out of the
terminal hinge position with the vertical axis of the opposite condyle remaining in the terminal hinge
position.
 This movement does not occur naturally.

13. Sagittal axis of rotation -
 Mandibular movement around the sagittal axis occurs when one condyle moves inferiorly while the
other remains in terminal hinge position.
 This type of movement also does not occur naturally.

14. 3 Reference planes of skull -
Divides face into
upper and lower
parts
Horizontal or Transverse
Divides face into
right and left parts
Sagittal
Divides face into
anterior and
posterior parts
Frontal or Coronal
Shows rotation
around frontal axis
Shows rotation
in transverse
horizontal axis
Shows rotation
in sagittal axis

15. 2. Translation -
 This refers to bodily movement of the condyle.
 It occurs during all the excursive mandibular movements.
 It is also known as sliding/gliding motion.
 If opening of the mandible continues beyond 20-25mm then translation of the mandible occurs.

16.  When the jaw is opened widely, it exceeds the maximum range of jaw opening with rotational
movement, and a secondary gliding movement occurs. This movement is called translation.
 Translation occurs within the upper compartment of the TMJ.

17. Centric Relation -
 CR is the mandibular jaw position in which the head of the condyle is situated as far anterior and
superior as it possibly can within the mandibular fossa/glenoid fossa.
 This position is independent of tooth contact.
 It is restricted to purely rotary movement about the transverse horizontal axis.

18. Maximal Intercuspal Position -
 The complete intercuspation of the opposing teeth independent of condylar position.
 It is sometimes referred to as the best fit of the teeth regardless of the condylar position.
 It is also known as maximal intercuspation.

19.  It occurs when mandible moves away from maximum intercuspation.
 In a completely edentulous situation, it can be assumed as any movement of the condyle from the
CR position as it coincides with MIP.
 Excursive movements are a combination of rotation and translation.
The excursive movements are - 1. Opening and Closing
2. Protrusion and Retrusion
3. Lateral excursion

20. MOVEMENT
Depression of mandible Opens mouth
Elevation of mandible Closes mouth
Protrusion Protraction of chin
Retrusion Retraction of chin
Lateral/ Side to side
movement
Chewing/ Grinding

21.  Border movements are mandibular movement at the limits dictated by anatomic structures, as viewed in a
given plane.
 These are extreme positions of the mandible in any direction limited by nerves, muscles and ligaments and
are closely associated with occlusal patterns.
 These positions can be recorded in 3 anatomic planes. They are -
1. Border movement in sagittal plane
2. Border movement in horizontal plane
3. Border movement in frontal plane
 Mandibular border movements are the nonfunctional movements of the mandible.

22. 1. Border movement in Sagittal Plane -
This traces the movement as the mandible moves from centric occlusion maximum protrusion
maximal mouth opening closing while returning to centric occlusion.
Beak shaped

23. 2. Border movement in Horizontal Plane -
This traces the movement from centric relation right and left extreme lateral movements maximal
protrusion centric relation.
Diamond shaped

24. 3. Border movement in Frontal Plane -
This traces the movement from centric relation right and left extreme lateral movements maximal
mouth opening back.
Shield shaped

25.  This is the 3-dimensional space circumscribed of all the border movements discussed.
 It was first described by POSSELT.
 All functional movements of the mandible occur within this envelope.
Definition - The 3-dimensional space circumscribed by mandibular border movements within which all
unstrained mandibular movements occur.

26.  Chewing, swallowing, speaking, yawning and associated movements constitute the functional
movements of the mandible.
 These take place within the border movements.
 The envelope of motion recorded during chewing appears as a characteristic “tear drop” and can be viewed
in all 3 planes.
Tear drop pattern of movement recorded while chewing in all 3 planes

27.  The movements are variable within the borders and are influenced by -
• Consistency, bulk and type of food

28.  These are sustained movements of the mandible that occur other than normal, manifested by long periods
of increased muscle activity.
 They are almost impossible for patients to control.
 2 most common parafunctional activities - • Bruxism
• Clenching
 Parafunctional movements of mandible are activities that serve no useful function and are potentially
harmful to the dentition and its associated structures.
 They can cause restricted mandibular movements.
 These have to be diagnosed and appropriate remedial measures need to be initiated , as they might affect
jaw relation records and prognosis of the prosthesis.

29. Functional activities Parafunctional activities
Chewing Bruxism
Swallowing Clenching
Speech Habits(pipe smoking, pencil biting,
safety pin opening)
Respiration
Yawning
Facial expression

30.  In complete denture wearers, a balanced occlusion is essential to prevent mandibular deflection and
displacement of dentures.
 During mandibular movements, the inclined planes of teeth should not disrupt the influence of condylar
guidance posteriorly and incisal guidance anteriorly.
 Deflective contacts produce variations in mandibular movements but patients tend to avoid this by
chewing on both sides at the same time during mastication.

31.  This is another important factor in regulating mandibular movement.
 The muscles responsible show increased activity and may be associated with movement, fixation or
stabilization of mandible such that there is a smooth and coordinated movement from one position to
another.
 The muscles perform their specific function because they receive impulses from central nervous system.
 The impulses may arise at the conscious or subconscious levels and result in voluntary or involuntary
muscular activity respectively.

32. Muscles Mandibular movements
Masseter Closing and Retrusion
Temporalis Elevation and Retrusion
Medial pterygoid Closing and Lateral movements
Lateral pterygoid Opening, Protrusion and Lateral movements
Suprahyoid group of muscles Depress the mandible assisted by infrahyoid
group of muscles
Muscles of
mastication

33.  In recording jaw relations
 For designing, adjustment and selection of articulator
 For creating a tooth form for dental restorations
 For understanding basic principles of occlusion
 For diagnosing and treatment of TMJ disturbances
 For preserving the periodontal health

35. Temporomandibular joint is the joint connecting your lower jaw and your skull.
The movements can be categorized as follows -
 Basic movements
 Excursive movements
 Border movements
 Functional movements
 Parafunctional movements
 Condylar path / guidance
 Opposing tooth contact and Anterior guidance
 Neuromuscular control
Factors affecting mandibular movements are -