TMJ Flashcards
What is the definition of the TMJ?
This is a Combination of a Plane and Hinge joint.
Formed by the Condylar process of the Mandible, the Mandibular fossa and Articular tubercle of the Temporal bone of the Skull.
What are all of the Anatomical components of the TMJ?
There is 5 Special components to the TMJ.
1: Articular Disc/ Meniscus
2: Articular Capsule
3: Lateral ligament
4: Sphenomadibular ligament
5: Stylomandibular ligament
What are the movements of the TMJ?
Only the mandible moves in this joint.
In the Superior compartment of the joint there is Protraction, Retraction, lateral Displacement, Slight rotation.
In the Inferior compartment there is Depression and Elevation for opening and closing your jaw.
What are the Different compartments to the TMJ?
There is a Superior compartment and an Inferior compartment.
They help perform different movements.
What does the Articular Disc / Meniscus do in the TMJ?
This is the Fibrocartilage disc that separates the Synovial Cavity into Superior and Inferior portions both with a synovial membrane.
What is the Articular Capsule in the TMJ?
It is a Fairly loose envelope around the circumference of the joint.
What is the Lateral Ligament in the TMJ?
This is extended from the Inferior boarder of tubercle and the Zygomatic Arch - to the Lateral posterior portion of the Mandible.
Used for preventing Displacement of the Joint.
What is the Sphenomandibular ligament of the TMJ?
A thin band that extends inferiorly and Anteriorly From the spine of the Sphenoid bone to the Ramus of the mandible.
Not used for Strength of the joint. Attaches on the interior portion of the Ramus.
What is the Stylomandibular Ligament of the TMJ?
Extending from the Styloud process to the Inferior and posterior boarder of the Ramus.
On the interior portion of the bone.
What does the Stylomandibular Ligament help do?
It Limits movement of the TMJ and Separates the Parotid gland from the Submandibular gland.
What is the resting position of the TMJ?
Mouth slightly open, lips together, teeth not in contact.
What is the closed packed position of the TMJ?
Teeth slightly clenched.
What would a capsular pattern of the TMJ be?
Limitation of mouth opening.
What are the bones that are involved with the TMJ?
Mandibular condyle/condylar process of mandible Mandibular fossa
Articular eminence.
What specifically is the TMJ classified as?
Synovial, bicondyloid/ modified hinge.
What are the movements the TMJ can perform?
Rotation and gliding
● Inferior portion (condyle) allows for rotation (first third of opening of the jaw)
● Superior portion (temporal bone) allows for gliding motion Elevation Depression Protrusion Retrusion Lateral Deviation
What are supporting structures of the TMJ?
Between the condyle and fossa is a biconcave articular disc
● Muscles involved are medial and lateral pterygoids, temporalis, masseter, supraand infra- hyoids
● Lateral ligament, Sphenomandibular ligament, Stylomandibular ligament.
What does the Articular Disc do for the TMJ?
The Disc is thin anteriorly and thick posteriorly.
the shape keeps the disc from being pulled too far forward when opening or closing
Where is the Disc of the TMJ attached?
Attached to capsule on inside and mandibular condyle in middle and on sides.
What are the details of the Articular capsule of the TMJ?
Very thin capsule that attaches around mandibular fossa superiorly and edge of
mandibular condyle inferiorly which holds synovial fluid and disc.
When mouth is closed capsule is lax, when mouth is open capsule is tight.
What are the Ligaments of the TMJ?
Tempomandibular/ Lateral ligament, Stylomandibular ligament, Sphenomandibular ligament.
What nerves are involved with the TMJ?
The TMJ is innervated by the “Articular temporal nerve”. This nerve also innervates the external auditory meatus, tympanic membrane, temporalis and masseter muscles.
Therefore, TMJ problems can result in tinnitus, loss of hearing, vertigo and muscle spasms.
What can TMJ pathologies also result in?
They can also result in hearing loss and lose of balance because the nerve that is involved with the TMJ also innervates with the Ear and muscles in the neck.
How far does the TMJ move naturally?
Depression 35-55mm Tissue stretch
Elevation Teeth touch Bone to bone
Protraction >7mm Tissue stretch
Retraction 3-4 mm Tissue stretch
Lateral Deviation 10-15 mm Tissue stretch
What is the role for the Lateral Ligament of the TMJ?
restrains movement of the lower jaw
and prevents compression of the tissues behind the condyle. In reality, this collateral ligament is a thickening in the joint capsule.
What is the role of the Stylomanibular ligament of the TMJ?
prevents excessive anterior movement of mandible during opening of mouth.
What is the role of the Sphenomandibular ligament of the TMJ?
prevents excessive anterior movements of mandible when mouth is fully open.
How much Tissue stretch does to TMJ naturally have in the movement of Depression?
35-55 mm of tissue stretch.
For the movement of the TMJ in Elevation when does the movement end?
When the Teeth touch.
During protraction of the the TMJ how far does the joint move?
> 7mm of tissue stretch.
During Retraction of the TMJ how far does the Joint move?
3-4 mm of tissue stretch.
When Lateral deviation occurs at the TMJ how far can the joint move?
10-15 mm of tissue stretch.
