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Gross Anatomy Module 4 > TMJ and muscles of mastication > Flashcards

TMJ and muscles of mastication Flashcards

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1
Q

TMJ

A

articulation between mandible and skull

modified hinge joint:

  1. articular eminence and tubercles of temporal bone
  2. mandibular fossa of temporal bone
  3. condyle of mandible
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2
Q

Mandibular fossa

A
  1. Receives mandibular condyle
  2. Articular surface covered with dense fibrous tissue
  3. Borders of mandibular fossa
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3
Q

Borders of mandibular fossa

A

Lateral
-Zygomatic process of temporal bone

Medial: spine of sphenoid bone

Anterior: articular eminence

Posterior: squamotympanic and petrotympanic fissures

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4
Q

Squamotympanic fissure

A

separates mandibular fossa of squamous portion of temporal bone from tympanic plate of temporal bone

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5
Q

Petrotympanic fissure

A

adj to small wedge of petrous temporal bone

*CHORDA TYMPANI PASSES THROUGH PETROTYMPANIC FISSURE

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6
Q

Mandibular condyle

A

Roller shaped w/ medial + lateral poles

  • long axis of condyles angled posteriorly
  • neck of condyle connects condyle to ramus of mandible
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7
Q

Articular surface of condyle

A

covered with dense fibrous tissue w/ isolated groups of chondrocytes + little surrounding matrix,
reflecting formation by intramembranous ossification

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8
Q

External oblique line

A

attachment for depressor anguli oris

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9
Q

Gonial angle

A

Junction of posterior border of ramus and inferior border of body of mandible

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10
Q

Antegonial notch

A

Junction of ramus and body of mandible

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11
Q

Digastric fossa

A

Anterior internal aspect, above inferior border.

Small depressions, anterior belly of digastric

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12
Q

Mental spine (genial tubercles)

A

Midline, superior to digastric fossae.
May be 4 or single fused spine
Genioglossus (upper aspect)
Geniohyoid (lower aspect)

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13
Q

Mylohyoid ridge (line)

A

Runs obliquely from lateral aspect of digastric fossae to below lingual alveolar crest of last mandibularmolar
– origin of mylohyoid muscle

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14
Q

Sublingual fossa

A

above mylohyoid line, accommodates sublingual gland

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15
Q

Submandibular fossa

A

below mylohyoid line, submandibular gland

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16
Q

Mandibular foramen

A

midpoint of ramus of mandible

17
Q

Mandibular canal

A

continuation of mandibular foramen, deep into mandible

  • runs inferiorly and anteriorly through ramus and body just below roots of mandibular teeth and ends at midline.
  • carries inferior alveolar n and artery to mandibular teeth
  • cutaneous branches pass to facial aspect of mandible via mandibular foramen
18
Q

Lingula

A

guards superoanterior border of mandibular foramen
- sphenomandibular ligament attached
May interfere with anesthetic injections of inferior alveolar n at mouth of mandibular foramen

19
Q

Mylohyoid sulcus (groove)

A

runs downward and forward from inferior border of mandibular foramen.
* n to mylohyoid muscle

20
Q

Coronoid notch

A

Concavity on anterior border of ramus as it approaches body below

21
Q

Internal oblique line (temporal crest)

A

buttressing ridge of bone on internal surface of ramus

  • slopes downward and forward
  • as it goes to last molar, divides to pass around last molar, divisions becoming continuous with buccal and lingual alveolar crests
  • enclosed triangle: retromolar triangle
22
Q

Retromolar fossa

A

depression between anterior border of ramus and temporal crest

23
Q

Articular disc

A

Bi-concave

  • allows flexibility in disc so it can conform during TMJ motion
  • allows disc to be self-centered
24
Q

Articular Disc Divisions

A

Divides joint into superior/inferior compartments

*disc attached to inner periphery of articular capsule by superior and inferior sheets or lamellae that continue superiorly and inferiorly to blend with walls of capsular ligament

superior lamella: elastic, inferior = collagen

25
Q

TMJ

A

like all synovial joints possesses fibrous capsule that encloses joint surface

26
Q

Capsular ligament, lateral/temperomandibular ligament

A

reinforcements of joint/intrinsic ligaments capsule region

- prevent excessive lateral movement and posterior dislocation

27
Q

Stylomandibular ligament

A

extrinsic ligament
- runs from styloid process to angle of mandible
limits protrusion

28
Q

Sphenomandibular ligament

A

Runs from spine of sphenoid to lingula of mandible

  • Supports weight of mandible
  • Prevents excessive lateral movements of mandible
29
Q

Movements of mandible

A
  1. Elevation/depression
    - fulcrum located approximately at mandibular foramen
  2. Protrusion/retrusion
  3. Lateral excursion (deviation)
30
Q

Hinging and Gliding at TMJ

A

Most mandibular movement

  • Hinge movement takes place in LOWER joint compartment
  • Gliding (translation) in upper joint compartment
  • Upon opening, both condyle and disc translate forward to sit on articular eminence
31
Q

Muscles of mastication

A
  1. Temporalis
  2. Masseter
  3. Lateral pterygoid muscle
  4. Medial pterygoid muscle
32
Q

Temporalis muscle

A

Attachments:

  1. temporal fossa
  2. tip of coronoid process, ramus of mandible
Action:
bilateral: elevation, REtrusion of mandible 
unilateral: ipsilateral deviation 
--holds resting position of mandible
Inn: Deep temporal branches
33
Q

Masseter muscle

A

Attachments:

  • outer and inner surfaces of zygomatic bone and arch
  • angle and lateral surface of ramus of mandible

Action:
Bilat: elevation, PROtrusion of mandible
Unilat: ipsilateral deviaion

Inn: masseteric n

34
Q

Lateral ptyergotd muscle

A

Attachments:
Superior head: greater wing of sphenoid
Inferior head: lateral pterygoid plate
Both: capsule, disc, condyle

Action:
Bilateral: depresses, protracts mandible
Unilateral: contralateral deviation
Inn: lateral pterygoid nerves

35
Q

Medial Pterygoid Muscle

A

Attachments:

  • Lateral pterygoid plate, tuberosity of maxilla
  • Medial ramus of mandible, inferior to mandibular foramen

Action:
Bilat: Elevation, PROtrusion
Unilat; CONTRAlateral devision
Inn: medial pterygoid nerve

36
Q

Nerve supply

A

Most of the TMJ supplied by sensory articular branches of auriculotemporal nerve

  • small anterior portion supplied by sensory fibers arising from masseteric branches of V3

-posterior and posterolateral regions of joint capsule contain free nerve endings - pain impulses from joint
(protection against excessive mandibular movement)

-retrodiscal inferior lamella has proprioceptive mechanoreceptors -detect condylar movement and position

37
Q

Blood supply

A
  • Articular branches from superficial temporal a to supply most of the joint
  • A from muscular branches of maxillary artery that supply anterior aspect of joint
38
Q

Examination of TMJ

A

Palate area
Muscles: temporalis and masseter

TMJ movement:
anterior: lateral aspect of TMJ palpated just anterior to ear. Pt opens/close while palpating bilaterally
Posterior: finger inside ears and press gently anteriorly.
Pt open/close several times, check for pain and equal motion bilaterally

-Auscultation may assist in evaluation

Gross Anatomy Module 4 (7 decks)

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