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Articulatio
Temporomandibularis - Temporomandibular joint - TMJ |
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Temporomandibular Joint - TMJ -
(Articulatio Temporomandibularis) is synovial
joint (has synovial cavity) by structure, diarthrodial joint
(allows movements) by function. It is known as ginglymo-arthrodial
joint (ginglymo and arthrodial are types of synovial joints).
Ginglymo means- it
slides (glides)
Arthrodial meand- it allows rotation
TMJ is a joint between
Mandibular Fossa in Temporal Bone and Condylar Process of Mandible;
I. Mandibular
Fossa ( Articular Fossa, Fossa Mandibularis) that is an anterior
part of the Glenoid Fossa (Fossa Glenoidalis)
Glenoidal
Fossa (Fossa Glenoidalis) is composed of:
1.Anterior part: Fossa Mandibularis
2.Middle part: Glaserian Fissure
(Petrotympanic Fissure, Fissura Petrotympanica)
3.Posterior part: which lodges a portion of the parotid gland (Glandula
Parotis)
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| Formation
of Mandibular fossa: |
Superior
and Anterior side: |
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Articular Eminence
(Eminentia Articularis) of the Zygomatic Bone (Os Zygomaticus)- most heavily
travelled by mandibular condyle.
Articular Tubercle (Tuberculum Articulare) is an outer
end of articular eminence and serves as attachment for TMJ ligament
(external-lateral ligament) |
Anterior
side (as part of Articular Eminence): |
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Pre-Glenoid
plane; almost horisontal articular surface( also known as Facies
Articularis or Path of Condyles). Together with Occlusal planeare making
an Articulation Angle of the TMJ |
Posterior
side: |
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Post-Glenoid
Process (Processus Postglenoideus) a sharp ridge positioned between
Mandibular fossa and External Acoustic Meatus (Meatus Acusticus Externus) |
II.
Condylar Process of the Mandible
(Processus Condylaris Mandibulae) |
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| Other parts
of Temporomandibular Joint: |
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Articular
Capsule
(Joint Capsule, Capsula articularis) |
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Articular
Capsule is a sac that encloses TMJ. Borders:
Superior: Capsule is positioned underneath inferior side of Articular Eminence.
Inferior: Capsule wraps around condyle's neck (Collum Mandibulae) |
Articular
Disc (Discus articularis)
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It
is a fibro-cartilageus disc. It divides synovial cavity of TMJ into:
1. Superior synovial cavity
2. Inferior synovial cavity
Both cavities are filled with synovial fluid, secreted by inner side of
articular capsule (clear, viscous fluid).
Attachments of articular disc: |
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1.Anterior:
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a. Anterio-Superior:
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indirectly to articular
eminence through
capsule
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b.Anterio-inferior: |
to condyl's neck
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| 2.Posterior: |
a.Posterio-superior: |
to post-glenoid process |
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b. Posterio-inferior: |
to condyl's neck
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Ligaments:
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1. TMJ ligament - External Lateral ligament (Ligamentum
lateralis temporomandibulare) |
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Short
ligament, positioned on the external lateral side of TMJ
Attachments:
Superior: lateral surface of articular eminence
Inferior: latero-posterior part of condyle's neck |
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2. Sphenomandibular ligament
(Ligamentum Sphenomandibulare) |
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Attachments:
Superior: Spinous process of sphenoid bone
(Processus spinosus os sphenoidale)
Inferior: Mandibular lingula (Lingula mandibulae)
Note: Inferior alveolar nerve (Nervus alveolaris
inferor) is located in the space between mandibular ramus and sphenomandibular
ligament (it descends towards mandibular foramen).This is an important landmark
for administration of inferor alveolar anesthetic block. |
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3. Stylomandibular ligament
(Ligamentum Stylomandibulare) |
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Attachments:
Superior: Styloid process of temporal bone (Processus styloideus ossis
temporalis)
Inferior: Angle of the Mandible (Angulus mandibulae)
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