Download Mandibular movements

ANATOMY
&
physiology
Dr.shanai M.
It is the articulation of the condyle of the
mandible, and the inter-articular disc; with the
mandibular fossa (glenoid fossa) of the
temporal bone.
The TMJ consist of the following parts:
• Mandibular condyle
• Glenoid fossa of Temporal bone
• Articular disc or Meniscus which found between
the condyle and the glenoid fossa.it divides the
synovial joint or TMJ into upper (superior) and
lower (inferior) compartments.
The TMJ can be divided into
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1.passive components:
A. bone
Mandibular fossa.
Condyle
Articular eminence.
B. capsule and ligaments
C. articular disk.
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2. Active components
A. Masticator muscles
Masseter
Temporalis
Medial pterygoid
Lateral pterygoid muscles
B. Additional muscles
The ligaments that effect the movements of the
mandible consist of:
1. Major ligaments
• Temporomandibular and capsular ligaments.
2.Minor ligaments:
• Sphenomandibular ligament.
• Stylomandibular ligament.
Other ligaments
• Oto mandibular ligament.
• Disco malleolar
• Mallelo mandibular ligaments
• The mandibular bone has specific relationships to the bones of the
cranium. The mandible is connected to the cranium at the two
temporomandibular joint by the temporomandibular and capsular
ligaments. the sphenomandibular and stylomandibular ligaments
also connect the bones in such away as to limit some motions of the
mandible.
The muscles that control the movement
There are three groups of muscles
1. Closing muscles.
2. Gliding muscles.
3. Opening muscles
Closing muscles (muscles that cause elevation
of mandible)
• A. The temporalis
• B. masseter
• C. medial pterygoid muscles supply the power for pulling the
mandible against the maxilla (elevating and closing the
mandible).
Opening muscles (muscles that depress
mandible)
• The lateral pterygoid muscles
• Suprahyoid muscles
• Platysma muscles
• Infrahyoid muscles
The muscles that cause protrusion of mandible
• Lateral pterygoid muscle
• Medial pterygoid muscle
• Masseter (superfacial fibers)
The muscles that cause retraction of mandible:
• Posterior fibers of temporalis muscle
• Masseter muscle (deep fiber)
Side to side movements (grinding and
chewing)
• Temporalis muscle on same side.
• Pterygoid muscles on opposite side
• Masseter muscle
• Good prosthodontic treatment bears a direct
relation to the structures of the
temporomandibular articulation, since
occlusion is one of the most important parts of
treatment of the patients with complete
dentures.
• The temporomandibular joints affect the
dentures and likewise the dentures affect
health and function of the joints.
Mandibular axis and mandibular movements
• There are three axis around which the mandibular
movements take place (sagittal, transverse (horizontal),
and coronal (frontal))
• 1- Hinge axis or transverse axis
• It is an imaginary line around which the mandible may
rotate within the sagittal plane (during opening and closing
movement).
2- Sagittal axis of the mandible
• It is an imaginary anteroposterior line around which the
mandible may rotate within the frontal plane.
3- Vertical axis of the mandible
• It is an imaginary line around which the mandible may
rotate through the horizontal plane.
Mandibular movements
Mandibular movements can be divided into two
types either basic or functional movement
1. Basic movements occur at the level of TMJ it
may be divided into two types
A. Rotational Movement: that occurs between the
condyle and the inferior surface of the articular
disk, i.e. in the lower compartment of the TMJ.
B. Translatory or gliding movement: it takes place
in the upper compartment of TMJ, i.e. between the
superior surface of the articular disk and the
glenoid fossa
• 2. Functional Movement: all mandibular
movements except the terminal hinge
movement, are combination of rotational and
transitional, are most frequently and are
referred to as being functional movements.
They include
• A. Opening and closing movement.
• B. Symmetrical forward and backward
movements.
• C. Asymmetrical side wise movement or
lateral movement
T H A N K
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