Week 1 - Temporalmandibular Joint Flashcards
What kind of joint is the TMJ?
diarthrodial synovial joint
The TMJ is located anterior to the ___.
external acoustic meatus of the temporal bone.
The TMJ connects the ___ bone from above and the ___ bone from below amid an _____, ____, and ___.
The TMJ connects the TEMPORAL bone from above and the MANDIBULAR bone from below amid an ARTICULAR DISC, LIGAMENTS, AND JOINT CAPSULE.
T/F: The TMJ is reported to be the most active joint in the body.
True
Dysfunction of the TMJ can lead to what two things?
- craniofacial pain
2. reduced functionality
What is dysfunction of the TMJ termed?
Temporomandibular Disorder (TMD)
TMD occurs when there is disruption to what? (2)
Joint and/ or Muscle Mechanics
What age and gender does TMD primarily affect?
All ages, females more than males especially during reproductive years.
What system is the TMJ part of?
Craniomandibular system.
What are the two end of the the Mandibular condyle?
Medial Pole and Lateral Pole
What is the name of the posterior process off the neck of the mandible?
Mandibular Condyle
What is the name of the anterior process off the neck of the mandible?
Coronoid Process
The mandible is broken up into what 3 regions?
- Neck
- Ramus
- Body
Describe the convex/concavity of the Articular Disc.
bi-concave (separates into two cavities)
What type of cartilage is the Articular Disc made of?
fibrocartilage (important because it is a load bearing joint)
Is the intermediate division of the Articular Disc vascularized or avascular?
avascular
Does the intermediate division of the Articular Disc have sensation or insensate?
insensate
Moving towards the the anterior and posterior divisions of the disc (the peripheral aspects), is the Articular disc vascularized or avascular?
vascularized
Moving towards the the anterior and posterior divisions of the disc (the peripheral aspects), does the Articular Disc have sensation or insenate?
has properties of sensation
Does the intermediate division or periphery of the disc attach to the joint capsule?
periphery
What 3 divisions is the Articular disc divided into?
Posterior, Intermediate, and Anterior
What do the three divisions of the Articular Disc represent?
accommodations to the contours of the mandibular condyle and the mandibular fossa.
Is the Temporal bone convex or concave?
Both, the mandibular fossa is concave, however the Articular eminence is convex.
Is the Mandibular condyle convex or concave?
Convex
T/F: TMJ has one synovial joint cavity within one larger joint.
False: TMJ has TWO synovial joint cavities within one larger joint.
What are the 2 joint cavities of the TMJ?
Inferior and Superior Joint Cavity
Where is the inferior joint cavity located?
between the mandibular condyle and the inferior surface of the disc
What type of joint is the inferior joint cavity?
Hinge Joint
Where is the superior joint cavity located?
between the superior surface of the disc and the mandibular fossa and the articular eminence of the temporal bone.
Does majority of the rotation occur at the superior or inferior joint cavity?
Inferior Joint Cavity (hinge joint)
What type of joint is the superior joint cavity?
Gliding Joint
The superior aspect of the joint capsule attaches to what 4 things?
- Mandibular Fossa
- Articular Eminence
- Periphery of the Anterior Aspect of the Disc
- Fibers of the superior head of the lateral pterygoid muscle.
The inferior aspect of the joint capsule attaches to what 5 things?
- Attaches to mandibular neck
- and articular disc
- blends in with the medial collateral
- and lateral collateral
- and TM ligament
How does the TMJ joint receive reinforcement? (2)
Fibrous Capsule and Ligaments
Are the medial and lateral or anterior and posterior compartments more firm? Why?
Medial and Lateral are more firm, Anterior and Posterior are considered more loose.
(allows for medial-lateral stability during chewing and mobility anterior-posterior for translation during opening and closing)
What are the 3 important ligaments around the TMJ?
-Temporomandibular Ligament (also known as lateral ligament)
2 Medial Accessory Ligament
-Stylomandibular Ligament
-Sphenomandibular Ligament
What purpose does the Temporomandibular Ligament have?
Supports the lateral wall of the capsule
What purpose do the 2 Medial Accessory Ligaments, Stylomandibular and Sphenomandibular Ligament have?
Reside on medial aspect of joint capsule and help suspend the mandible from the cranium.
May also prevent excessive protrusion.
What purpose do the superficial oblique fibers of the Temporomandibular Ligament have?
limit rotation of the condylar head during opening
What purpose do the deeper horizontal fibers of the Temporomandibular Ligament have?
limit posterior displacement of the condylar head thus protecting the retro-distal region of this joint
What are the two primary roles of the TMJ?
- The ability for it to open and close
2. Manage food in terms of tearing and grinding for digestion
What muscles allow for the Action at the TMJ: depression
- Lateral Pterygoid (inferior fibers)
- Suprahyoids
- Infrahyoids
What muscles allow for the Action at the TMJ: elevation
- Temporalis
- Masseter
- Medial Pterygoid
What muscles allow for the Action at the TMJ: lateral deviation
- Temporalis (ipsilateral)
- Masseter (ipsilateral)
- Medial Pterygoid (contra lateral)
- Lateral Pterygoid (contral lateral)
What muscles allow for the Action at the TMJ: protrusion
- Bilateral Superficial Masseter
- Medial Pterygoid
- Lateral Pterygoid
What muscles allow for the Action at the TMJ: retrusion
- Deep Fibers of Masseter
- Temporalis
- Suprahyoids
What are the 5 functions of the Articular Disc?
- Improve congruency for joint articulations
- Stability
- Minimizes loss of mobility
- Reduces friction
- Decreases stress on the TMJ
What is the Origin of: Temporalis
- Temporal Fossa
What is the Insertion of: Temporalis
- Coronoid Process
2. anterior aspect of the Ramus of the mandible
What is the Action on the TMJ of: Temporalis
- Elevation
- Lateral Deviation (ipsilateral)
- Retrusion
What is the Origin of: Masseter
Superficial:
- Zygomatic process of the maxilla
- 2/3rd of lower border of the Zygomatic Arch
Deep:
1. Zygomatic Arch
What is the Insertion of: Masseter
Superficial:
- Ramus of the mandible
- Angle of the mandible
Deep:
- superior 1/2 of the Ramus
- lateral surface of the Coronoid Process
What is the Action on the TMJ of: Masseter
- Elevation
- Lateral Deviation (ipsilateral)
- Protrusion (superficial fibers)
- Retrusion (deep fibers)
What is the Origin of: Medial Pterygoid
- Palatine bone
2. tuberosity of the Maxilla
What is the Insertion of: Medial Pterygoid
- medial surface of the Ramus
2. Mandibular Angle
What is the Action on the TMJ of: Medial Pterygoid
- Elevation
- Lateral Deviation (contralateral)
- Protrusion
What is the Origin of: Lateral Pterygoid (superior head)
- Greater Wing of Sphenoid bone
What is the Insertion of: Lateral Pterygoid (superior head)
- Condylar Head
2. Articular Disc
What is the Action on the TMJ of: Lateral Pterygoid (superior head)
- Lateral Deviation (contralateral)
2. Protrusion
What is the Origin of: Lateral Pterygoid (inferior head)
- Lateral Surface of the Lateral Ptyerygoid Plate
What is the Insertion of: Lateral Pterygoid (inferior head)
- Neck of condyle
What is the Action on the TMJ of: Lateral Pterygoid (inferior head)
- Depression
- Lateral Deviation (contralateral)
- Protrusion
What is the Origin of: Suprahyoids (in general)
Above the Hyoid bone / Inferior aspect of the Mandible
What is the Insertion of: Suprahyoids (in general)
Hyoid Bone
What is the Action on the TMJ of: Suprahyoids (in general)
- Depression
2. Retrusion
What are Normal AROM values for: Depression (opening)
40-50mm
What are Normal AROM values for: Elevation (closing)
Full occlusion
What are Normal AROM values for: Lateral Deviation
10-12mm
What are Normal AROM values for: Protrusion
6-9mm
What are Normal AROM values for: Retrusion
3mm
What are the 2 “general” rules for movement looking at the normal arthrokinematics of the TMJ?
- During rotation, the mandibular condyle rolls relative to the inferior surface of the disc (inferior joint cavity)
- During translation, the mandibular condyle and articular disc slide together (superior joint cavity)
T/F: the TM joints are 2 distinct joints that need to work independently.
True
What percent of ROM is Early Phase of mouth opening?
35-50% of the initial ROM
What percent of ROM is Late Phase of mouth opening?
Final 50% of TMJ ROM
Does the Early Phase of mouth opening happen in the inferior or superior TM joint cavity?
inferior TM joint cavity
Does the Late Phase of mouth opening happen in the inferior or superior TM joint cavity?
superior TM joint cavity
Describe the primary movement of the Early Phase of mouth opening.
Posterior rotation is the primary phase of mouth opening. The mandibular condyle rolls in a posterior and inferior direction.
What initiates the transition from Early Phase to Late Phase of mouth opening?
As the mandible continues to rolls posteriorly, the oblique fibers of the TM ligament get placed on stretch resulting in increased tension in this ligament thus initiating the late phase of mouth opening.
Describe the primary movement of the Late Phase of mouth opening.
Moves from rotation to more of a translatory motion. Together, the condyle slide (translate) in an anterior direction against the slope of the articular eminence of the temporal bone.
How does the end of Late Phase of mouth opening initiate the closing of the mouth?
When full mouth opening is reached, tension pulls and stretches the disc anteriorly. The end ROM initiates closing of the mouth due to the tension in the superior retrodiscal lamina.
Describe the Early Phase of mouth closing.
Increased tension of the superior retrodiscal lamina retracts the disc moving the head of the mandibular condyle and disc to translate posteriorly, the body of the condyle moves anteriorly as the jaw closes.
Describe the Late Phase of mouth closing.
At the last phase of closing, rotation occurs as the head of the condyle is seated in the resting position in the mandibular fossa with the disc slightly anterior due the pull of the superior head of the lateral pterygoid and relaxation of the posterior retrodiscal tissues. Closing ends when the upper and lower teeth make contact.
Judy is a 42 y.o. female who was referred to physical therapy for pain in her right jaw. During the history taking of the initial examination, Judy reports her jaw only hurts when she chews food on her right side of her mouth or moves her jaw to the right. Based on this information what is your initial hypothesis?
- Judy is having pain during Right lateral deviation, opening, closing and possibly protrusion with the primary complaint of Right lateral deviation. This may be due to joint restrictions present in the Right or Left TM joint which causes impairment with side to side translation of the condyle and disc.
- There also could be an articular disc-condyle disorder known as an internal derangement. The muscles that contribute to Right lateral deviation associated with side to side grinding of food may be weak, hypertonic and/or have a motor control deficit.
What are the 4 primary muscles of mastication that are involved in TMJ function?
- Temporalis
- Masseter
- Medial Pterygoid (2 heads)
- Lateral Pterygoid (2 heads)
Where do the 4 primary muscles of mastication involved in TMJ function receive their nerve innervation from?
The mandibular division of the Trigeminal Nerve (aka CN V)
In addition to the primary muscles of mastication, what other muscles also play an important role?
Supra and Infrahyoid muscles
The American Academy of Orofacial Pain classifies TMD as ____.
a collection of symptoms that involve the TMJ and surrounding structures.
What are the 8 common signs/symptoms of TMD?
- Pain (TMJ and surrounding regions)
- Tinnitus, ear pain, congestion-like symptoms in the ear
- Dizziness
- Headache
- Joint Sounds (popping, clicking, grinding)
- Limited mandibular range of motion
- Reduced occlusion
- Joint Locking
- Describe the muscle and joint interactions during opening and closing of the mouth.
Depression of the mandible involves the inferior head of Later Pterygoid and Suprahyoid muscle group. The first 11 degrees includes rotation. Early phase of opening is 35-50% of ROM with the body of mandible moving posterior and inferior. Late phase of opening is the final 50% ROM moving from rotation to a translator motion. The Condyle and Disc move together forward and inferior. Maximal anterior stretch on the disc occurs
Elevation of the mandible involves the Masseter, Medial Pterygoid, and Temporalis. Closing is the reverse order of opening. Tension from the retrodiscal lamina retracts the disc. Translation occurs first followed by rotation last.