part 1 clined TMJ

What are the parts of the TMJ?

Mandible

Maxilla

Temporal

Sphenoid

Hyoid

Fibrocartilaginous Disk

2 Divisions of the TMJ

● Jaw;supportsthelowerteeth

● Largest & strongest bone in the face

● Suspended below maxilla by muscles and ligaments that provide both mobility and stability

MANDIBLE

Parts of the Mandible?

Condyle

Coronoid Process

A part of the mandible:

○ Posterior ramus

○ Articulates with the temporal bone

CONDYLE

A part of the mandible:

○ Anterior ramus

○ Attachment for temporalis and masseter

Coronoid process

● Contains 32 permanent teeth along with the mandible

MAXILLA

What are the parts of Maxilla?

Superior border

Inferior border

A part of maxilla:

Forms the nasal cavity and floor of each orbit

SUPERIOR BORDER ○

A part of maxilla

○ Forms the palate and the alveolar ridges

● INFERIOR BORDER

● Houses the mandibular fossa which is divided into two surfaces

TEMPORAL

What are the parts of the Temporal?

Articulating surface

Nonarticulating surface

A part of the temporal:

○ Made up of concave mandibular fossa and a convex articular eminence

ARTICULATING SURFACE

A part of the temporal:

○ Consists of a very thin layer of bone and fibrocartilage that occupies much of the superior and posterior walls of the fossa

● NONARTICULAR SURFACE

● The greater wings of the sphenoid bone form the boundaries of the anterior part of the middle cranial fossa

SPHENOID

● “Skeleton of the tongue”

● U-shaped bone serving as attachment for infrahyoid muscles

HYOID

● Found between articulating surface of the temporal bone and the mandibular condyle

FIBROCARTILAGINOUS DISK

What are the 2 divisions of the TMJ?

LOWER COMPARTMENT

• Borders: mandibular condyle and inferior surface of the disk

• Where osteokinematic spin(rotation) occurs

UPPER COMPARTMENT

• Borders: mandibular fossa and superior surface of the articular disk

• Allows translation of the disk and condyle

What division is this of the TMJ?

• Borders: mandibular condyle and inferior surface of the disk

• Where osteokinematic spin(rotation) occurs

lower compartment

What division is this of the TMJ?

• Borders: mandibular fossa and superior surface of the articular disk

• Allows translation of the disk and condyle

UPPER COMPARTMENT

○ A synovial, condylar, modified ovoid, and hinge type joint formed between the articular eminence of the temporal bone, the intra-articular disk, and the head of the mandible

○ Articulating surfaces covered with fibrocartilage

○ A tri joint complex

● TEMPOROMANDIBULARJOINT

Resting pack position of TMJ

Mouth slightly open, lips together, teeth not in contact

Closed pack position of TMJ

Teeth tightly clenched

Capsular pattern of TMJ

Limitation of mouth opening

Enumerate the ligaments of the TMJ

[CTSS]

CAPSULAR LIGAMENT (JOINT CAPSULE)

TEMPOROMANDIBULAR (LATERAL) LIGAMENT

SPHENOMANDIBULAR LIGAMENT

STYLOMANDIBULAR LIGAMENT

What ligament is this of the TMJ?

○ Surrounds the entire joint

○ Provide proprioceptive feedback

CAPSULAR LIGAMENT(JOINT CAPSULE)

What ligament is this of the TMJ?

○ Restrains movement of the lower jaw

○ Also resists rotation and posterior displacement of the mandible

● TEMPOROMANDIBULAR (LATERAL) LIGAMENT

What ligament is this of the TMJ?

○ Serves as a suspensory ligament of the mandible during wide opening

● SPHENOMANDIBULAR LIGAMENT

What ligament is this of the TMJ?

○ Act as “guiding” restraints to keep the condyle, disc, and temporal bone firmly opposed

● STYLOMANDIBULAR LIGAMENT

What are the muscles of the TMJ?

TEMPORALIS

INTERNAL (MEDIAL) PTERYGOID

MASSETER

EXTERNAL (LATERAL) PTERYGOID

What muscle is this of the TMJ?

○ Action: mouth closing (mandibular elevation) and side-to-side grinding of the teeth

● TEMPORALIS

○ Action: (bilateral) assists temporalis and masseter with mouth CLOSING

○ (Unilateral) DEVIATION OF MANDIBLE to the opposite side

○ Assists lateral pterygoid and temporalis in the PROTRUSION of the mandible

● INTERNAL(MEDIAL)PTERYGOID

○ Action: mouth closing occluding the teeth during mastication

● MASSETER

○ Action: mainly chewing

○ Jaw opening (mandibular depression)

○ Deviation of the mandible to the opposite side

● EXTERNAL (LATERAL) PTERYGOID

TMJ BIOMECHANICS

• The TMJ has 3 DOF

• PRIMARY ARTHROKINEMATIC MOVEMENTS:

  • _____

  • _____

• _____: Gliding, translation, or sliding movement

• _____: Rotation or hinge movement

TMJ BIOMECHANICS

• The TMJ has 3 DOF

• PRIMARY ARTHROKINEMATIC MOVEMENTS:

  • Rotation

  • Anterior translation

• UPPER CAVITY: Gliding, translation, or sliding movement

• LOWER CAVITY: Rotation or hinge movement

What are the phases in Mouth Opening (Mandibular depression)?

EARLY PHASE (ROTATION > TRANSLATION)

LATE PHASE (TRANSLATION > ROTATION)

What phase is this?

○ Mandibular condyle rolls anteriorly about the articular disc within the mandibular fossa (condylar anterior rotation), causing downward rotation of the mandible

○ Slight anterior translation of the mandible

● EARLY PHASE (ROTATION > TRANSLATION)

What phase is this?

○ Very little downward condylar rotation

○ Mandibular condyle slides anteriorly on the articular disc relative to the mandibular fossa

○ Movement puts tension on the articular disc

● LATE PHASE (TRANSLATION > ROTATION)

ARTHROKINEMATIC STEPS OF THE TMJ

Movement:

• Joint is an open-packed position

Resting position

ARTHROKINEMATIC STEPS OF THE TMJ

Movement:

• There is a mid-opening

• Condylar joint surfaces glide forward, inferior joint surface of disk has a relative posterior glide, upper lateral pterygoid relaxes, inferior pterygoid contracts, and posterior connective tissue is in a functional state of rest

Rotation

`

ARTHROKINEMATIC STEPS OF THE TMJ

Movement:

• Disk and condyle experience a short anterior translatory glide; superior and inferior heads of lateral pterygoid contract to guide disk and condyle forward

• Posterior connective tissue is in a functional tightening

Functional Opening

`

ARTHROKINEMATIC STEPS OF THE TMJ

Movement:

• There is full opening

• Disk and condyle glide anteriroly and caudally.

• Superior and inferior heads of lateral pterygoid contract to guide disk and condyle fully forward

• Posterior connective tissues tighten

Translation

`

ARTHROKINEMATIC STEPS OF THE TMJ

Movement:

• Surface of condyle joint glides posteriorly, and disk glides relative to anterior surface

• Superior head of lateral pterygoid contracts and inferior head relaxes

• Posterior connective tissue returns to its functional length

Closure