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DMD 5221 > TMJ > Flashcards

TMJ Flashcards

1
Q

What are the structural components of TMJ?

A
  • Squamous part of temporal bone
  • Condylar head of mandible
  • Articular disc
    • Contained within the TMJ (between temporal and mandible)
  • Ligaments
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2
Q

TMJ joint classifiication

A

Ginglymoarthrodial joint

  • Articular disc divides joint into upper and lower
    • Gliding - upper
      • Translation
      • Protrusion/protraction; retrusion/retraction
      • Upper part of joint
    • Hinge
      • Rotation
      • Elevation; depression
      • Lower part of joint
  • Diarthritic joint - capable of free movement
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3
Q

What kind of cartilage is the mandibular fossa covered with?

How is this different from other articular surfaces in the body?

Where is the cartilage the thickest?

A

Avascular fibrocartilage

Other joints in body have hyaline cartilage

Thickest in load-bearing areas i.e. squamous portion, disc, condyle

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4
Q

What are anterior, intermediate, posterior relations to the squamous portion of the temporal bone?

A
  • Anterior
    • Articular eminence becoming articular tubercle
      • Attachment for capsule and lateral (tempromandibular) ligament
  • Intermediate
    • Glenoid (mandibular) fossa
      • Depression for condyle
      • Thin layer of compact bone
  • Posterior
    • Petrotympanic (squamotympanic) fissure
    • Tympanic plate tapering to post-glenoid tubercle
      • Attachment for capsule and retrodiscal pad
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5
Q

What kind of bone makes up the mandibular condyles?

A

Cancellous (spongy) covered with a thin layer of compact

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6
Q

What are the mediolateral and anteroposterior measurements of mandibular condyles?

A

Mediolateral: 20mm

Anteroposterior: 10mm

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7
Q

What is the articular disc comprised of?

A

Dense fibrous CT

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8
Q

What is unique about the articular disc, in terms of innervation and blood supply?

A

Avascular and aneural in intermediate portion (high load bearing)

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9
Q

List the articular disc bands in order from thinnest to thickest

A

Intermediate < Anterior < Posterior

  • Anterior
    • Thick
    • Anterior to condyle with mouth closed
  • Intermediate
    • Thin
    • Along articular eminence with mouth closed
  • Posterior
    • Thickest portion of the disc
    • Superior to condyle with mouth closed
    • Attached to bilaminar zone including retrodiscal pad
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10
Q

What are the articular disc attachments?

A
  • Medial/lateral
    • Strong collateral attachments
    • Attach disc to condyle
  • Anterior
    • Disc attached to capsule and superior head of lateral pterygoid
  • Posterior
    • Disc is contiguous with bilaminar zone, blends with the capsule
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11
Q

What is the bilaminar zone?

A

Bilaminar structure posterior to articular disc

Highly distortable when opening mouth

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12
Q

What is the bilaminar zone composed of?

A
  • Superior lamina
    • Elastic fibers
    • Anchor suprioer part o posterior disc to the capsule and bone, postglenoid tubercle and tympanic plate
  • Retrodiscal pad
    • Most vascular and neural portion of TMJ
    • Collagen, elastic fibers, fat, nerves, BVs
  • Inferior lamina
    • Collagen
    • Anchors inferior aspect of posterior disc to the capsule
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13
Q

What TMJ compartment secretes synovial fluid?

A

Synovial membrane, lining TMJ

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14
Q

What are the volumes of the superior and inferior TMJ compartments?

A

Superior: 1.2mL

Inferior: 0.9mL

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15
Q

Fibrous (joint) capsule or capsular ligament

A
  • Completely encloses the articular surface of temporal bone and condyle
  • Sensory receptors
  • Outer fibrous layer
    • Fibrous CT
    • Toughened along medial and lateral aspects by ligaments
  • Inner synovial layer
    • Lined by highly vascular synovial membrane
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16
Q

What are the different capsule attachments?

A
  • Superior
    • Rim of temporal articular surfaces
  • Inferior
    • Condylar neck
  • Medial
    • Medial collateral ligament
  • Lateral
    • Lateral collateral ligament
  • Anterior
    • Superior head of lateral pterygoid m.
  • Posterior
    • Retrodiscal pad
17
Q

Collateral (discal) ligaments

A
  • Medial collateral ligament
    • Connects medial articular disc to medial side of condyle
  • Lateral collateral ligament
    • Connects lateral articular disc to lateral side of condyle
  • Called discal ligaments
  • Composed of collagenous CT - DO NOT stretch
18
Q

What are the extracapsular ligaments

A

Lateral temporomandibular ligament

Stylomomandibular ligament

Sphenomandibular ligament

19
Q

Lateral temporomandibular ligament

A
  • Closest to the joint
  • Just lateral to the capsule, blends with it
  • Margin of the articular tubercle to the neck of the mandible
  • Prevents lateral displacement of condyle
  • 2 separate bands
    • Outer oblique
      • Largest portion
      • Limits opening of mandible
    • Inner horizontal
      • Smaller band
      • Limits posterior movement of articular disc and condyle
20
Q

Sphenomandiblar ligament

A
  • Medial to TMJ
  • Spine of sphenoid bone to the lingula
  • Remnant of Meckel’s cartilage
  • Acts as a pivot on mandible
  • Limits max opening of jaw
21
Q

Stylomandibular ligament

A
  • Styloid process of temporal bone to posterior margin and angle of mandible
  • Composed of deep cervical fascia thickening
  • Limits anterior protrusion of mandible
  • Relaxed when mouth is closed, tense with extreme protrusion
22
Q

Arterial supply

A

External Carotid Artery

  • Superficial temporal a.
  • Maxillary a.
    • Deep auricular a.
    • Anterior tympanic a.
    • Masseteric a.

NOT lingual

23
Q

TMJ sensory innervation

A
  • Auriculotemporal n.
    • ​Post. division of V3
    • Sensory branches to TMJ, capsule
    • Primary innervation of TMJ
  • Masseteric n.
    • ​Ant. divison of V3
    • Sensory to TMJ
  • Posterior deep temporal n.
    • ​Ant. division of V3
    • Motor to TMJ
24
Q

m. closing/elevating the mandible

A

masseteric

medial pterygoid

temporalis

25
Q

m. opening/depressing the mandible

A

gravity

lateral pterygoid (primary)

mylohyoid, digastric, geniohyoid (secondary)

26
Q

m. protraction/protrusion of mandible

A

lateral pterygoid (primary)

medial pterygoid and masseter (secondary)

27
Q

m. retraction/retrusion of mandible

A

temporalis (primary)

mylohyoid, digastric, geniohyoid (secondary)

28
Q

m. lateral movement of mandible

A

lateral pterygoid (primary)

  • R lateral pterygoid moves mandible L
  • L lateral pterygoid moves mandible R

all other mastication mm. (secondary

29
Q

Opening the mandible

A
  • Rotational (lower compt)
  • Inferior head of lateral pterygoid initiates jaw opening
  • As mandible is depressed collateral (discal) ligaments tightly attach the condule to articular disc, only allow rotational movement
  • Once TMJ is taut, no more rotation
  • Normally rotational movement continues until upper and lower teeth are 20mm apart
  • Translational movement occurs in upper TMJ, so mandible finishes opening
  • Articular disc and condyle complex slide inferiorly on the articular eminences, allowing max depression of mandible

DMD 5221 (8 decks)

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