TMJ

Question 1

What is the definition of the TMJ?

Answer 1

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.

Question 2

What are all of the Anatomical components of the TMJ?

Answer 2

There is 5 Special components to the TMJ.

1: Articular Disc/ Meniscus
2: Articular Capsule
3: Lateral ligament
4: Sphenomadibular ligament
5: Stylomandibular ligament

Question 3

What are the movements of the TMJ?

Answer 3

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.

Question 4

What are the Different compartments to the TMJ?

Answer 4

There is a Superior compartment and an Inferior compartment.
They help perform different movements.

Question 5

What does the Articular Disc / Meniscus do in the TMJ?

Answer 5

This is the Fibrocartilage disc that separates the Synovial Cavity into Superior and Inferior portions both with a synovial membrane.

Question 6

What is the Articular Capsule in the TMJ?

Answer 6

It is a Fairly loose envelope around the circumference of the joint.

Question 7

What is the Lateral Ligament in the TMJ?

Answer 7

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.

Question 8

What is the Sphenomandibular ligament of the TMJ?

Answer 8

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.

Question 9

What is the Stylomandibular Ligament of the TMJ?

Answer 9

Extending from the Styloud process to the Inferior and posterior boarder of the Ramus.
On the interior portion of the bone.

Question 10

What does the Stylomandibular Ligament help do?

Answer 10

It Limits movement of the TMJ and Separates the Parotid gland from the Submandibular gland.

Question 11

What is the resting position of the TMJ?

Answer 11

Mouth slightly open, lips together, teeth not in contact.

Question 12

What is the closed packed position of the TMJ?

Answer 12

Teeth slightly clenched.

Question 13

What would a capsular pattern of the TMJ be?

Answer 13

Limitation of mouth opening.

Question 14

What are the bones that are involved with the TMJ?

Answer 14

Mandibular condyle/condylar process of mandible Mandibular fossa

Articular eminence.

Question 15

What specifically is the TMJ classified as?

Answer 15

Synovial, bicondyloid/ modified hinge.

Question 16

What are the movements the TMJ can perform?

Answer 16

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

Question 17

What are supporting structures of the TMJ?

Answer 17

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.

Question 18

What does the Articular Disc do for the TMJ?

Answer 18

The Disc is thin anteriorly and thick posteriorly.

the shape keeps the disc from being pulled too far forward when opening or closing

Question 19

Where is the Disc of the TMJ attached?

Answer 19

Attached to capsule on inside and mandibular condyle in middle and on sides.

Question 20

What are the details of the Articular capsule of the TMJ?

Answer 20

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.

Question 21

What are the Ligaments of the TMJ?

Answer 21

Tempomandibular/ Lateral ligament, Stylomandibular ligament, Sphenomandibular ligament.

Question 22

What nerves are involved with the TMJ?

Answer 22

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.

Question 23

What can TMJ pathologies also result in?

Answer 23

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.

Question 24

How far does the TMJ move naturally?

Answer 24

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

Question 25

What is the role for the Lateral Ligament of the TMJ?

Answer 25

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.

Question 26

What is the role of the Stylomanibular ligament of the TMJ?

Answer 26

prevents excessive anterior movement of mandible during opening of mouth.

Question 27

What is the role of the Sphenomandibular ligament of the TMJ?

Answer 27

prevents excessive anterior movements of mandible when mouth is fully open.

Question 28

How much Tissue stretch does to TMJ naturally have in the movement of Depression?

Answer 28

35-55 mm of tissue stretch.

Question 29

For the movement of the TMJ in Elevation when does the movement end?

Answer 29

When the Teeth touch.

Question 30

During protraction of the the TMJ how far does the joint move?

Answer 30

> 7mm of tissue stretch.

Question 31

During Retraction of the TMJ how far does the Joint move?

Answer 31

3-4 mm of tissue stretch.

Question 32

When Lateral deviation occurs at the TMJ how far can the joint move?

Answer 32

10-15 mm of tissue stretch.