A23 - Tempomandibular Joint Flashcards

1
Q

what are the properties of a typical synovial joint?

A
  • articular surfaces are lined by hyaline cartilage
  • non-articular surfaces lines with synovial membrane
  • capsule to enclose and retain fluid
  • ligaments to strengthen joint
  • skeletal muscles to move joint
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2
Q

What is the importance of the synovial membrane?

A
  • contains fluid to nourish the articular surfaces
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3
Q

What does the synovial fluid do?

A
  • reduces friction
  • to cool the joint
  • to remove waste products
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4
Q

What is the difference between the TMJ joint?

A
  • all articular surfaces are FIBROUS
  • temporal bone is covered in periosteum
  • infra-articular disc is made of dense fibrous tissue
  • head of mandibular condyle in perichondrium
  • infra-articular disc is split into superior and inferior synovial cavities with their own synovial membrane
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5
Q

what makes up the TMJ?

A
  • base of the temporal bone
  • glenoid fossa of temporal bone
  • head of the mandibular condyle
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6
Q

what is the function of the articular tubercle and where is it situated?

A

anterior to the glenoid fossa and prevents anterior dislocation

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7
Q

what is posterior to the glenoid fossa?

A

post-glenoid tubercle which prevents posterior disslocation

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8
Q

why is the post -glenoid tubercle less pronounced?

A

there are ligaments which also prevent dislocation

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9
Q

what is the function of the ptyergoid fovea?

A

where the lateral ptyergoid attaches and the disc is structurally connected to the ligament of this muscle

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10
Q

what is the key features of the condyle head?

A
  • elongated latero-medially

- tilted anteriorly which helps it optimally articulate with the glenoid fossa

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11
Q

what is the joint capsule?

A

bandage that wraps around the joint to keep it complete, aiding stabilisation and keeps the synovial fluid in the joint

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12
Q

what ligament prevents posterior dislocation?

A

lateral temporomandibular ligament

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13
Q

what is the structure and function of the stylomandibular ligament?

A
  • connects from the styloid process to the medial aspect of the angle of the mandible
  • specialisation of the investing layer of deep cervical fascia surrounding the parotid gland
  • weak ligament and restricts jaw openong
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14
Q

what is the importance and structure of the sphenomandibular ligament ?

A
  • arises in the spine of the sphenoid and attached to the lingual
  • main action is to prevent excessive jaw opening
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15
Q

what is the structure and function of the pterygomandibular raphe?

A
  • extends from the hamulus of the pteygoid plate of the sphenoid down towards the retro-molar space
  • role in attachment of other soft tissue including the buccinator muscle
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16
Q

what is the clinical relevance of the pterygomandibular raphe?

A
  • used in the location of the inferior alveolar nerve block

- needle inserted in-between the coronoid notch and the pterygomandibular raphe

17
Q

What is the importance of the intra-articular disc?

A
  • merges with the joint capsule ensuring the separation of the joint into and upper and lower space
  • provides stability of the joint during movement by ensuring a better fit between the mandible and the glenoid fossa
  • contains dense fibrous connective tissue
  • nerve receptors in the disc innervated by the auriculo-temporal nerve
18
Q

What is the structure of the disc - anterior extension?

A

anterior extension - continuous with the joint capsule anteriorly and with the tendon of the lateral pteygoid

19
Q

what is the process of initial jaw opening?

A
  • anterior rotation of the head of condyle
  • movemny occurs in the lower joint space
  • disc remains in place
20
Q

what is the process of full jaw opening?

A
  • after initial opening the disc then translates anteriorly articulating with the mandibular fossa and articular eminence
  • occurs in the upper joint space
21
Q

what is the difference between internal derangement with reduction and without reduction?

A
  • the disc gets stuck as the elastic fibre have become weakened
  • with reduction it will return to its normal position itself without it needs clinical assistance
22
Q

What causes dislocation of the TMJ’s ?

A
  • occurs when the mandibular condyle becomes fixed in the anterosuperior aspect of the articular eminence
  • spasm of the muscles of facial expression result in trismus, preventing the return of the condyle to the temporal fossa
23
Q

describe the movement of the TMJ when the jaw opens

A
  • bilateral and symmetrical depression
  • initial anterior rotation
  • subsequent anterior translation
  • maximum normal opening > 3 fingersbreadth
24
Q

describe the jaw closing movement of the TMJ

A
  • bilateral and symmetrical depression
  • initial posterior translation
  • subsequent posterior rotation
25
Q

describe lateral movements of the TMJ

A
  • bilateral and asymmetrical
  • working side lateral rotation/movement
  • non-working slide anterior and medial rotation
26
Q

describe the movement of the TMJ during protrusion and retrusion

A

protrusion - the mandible can be pulled forwards relative to the maxilla

retrusion - the mandible can be pulled backwards relative to the maxilla

27
Q

what is the structure of the disc - posterior extension?

A

posterior extension - it is bilaminar. the superior head contains elastic fibres which pull the jaw to its resting position after opening . the inferior has a rich blood supply that fills with blood on opening, filling the space allowing good articulation and then empties on closing by draining into pterygeoid venous plexus

28
Q

what is the structure of the disc - disc proper?

A

disc proper - form a doughnut shaped as it as a think anterior and posterior band and a thin intermediate zone