Muscles of Mastication Flashcards
What is the origin of the masseter?
zygomatic arch
What is the insertion of the masseter?
lateral surface and angle of the mandible
What is the action of the masseter?
elevate the mandible
How do you examine the masseter?
- place one finger intra-orally
- place one finger extra-orally on the cheek
- palpate
- tenderness indicates a clenching habit (bruxism)
What is the origin of the temporalis?
floor of the temporal fossa
What is the insertion of the temporalis?
coronoid process and anterior border of the ramus
What is the action of the temporalis?
elevates and retracts the mandible
How do you examine the temporalis?
- palpate at the temples
- ask the patient to clench together
- tenderness indicates a clenching habit (bruxism)
What is the origin of the lateral pterygoid?
lateral surface of the lateral pterygoid plate
What is the insertion of the lateral pterygoid?
inferior belly = anterior border of the condyle
superior belly = intra-articular disc
What is the action of the lateral pterygoid?
- protrudes and laterally deviates the mandible
- inferior head assists with the mandibular depressors
What can cause a clicking noise during opening of the mouth?
superior head of the lateral pterygoid pulling on the intra-articular disc
How do you examine the lateral pterygoid?
- not accessible to palpation
- response to resisted movement is used instead
- ask patient to move jaw laterally and push in the opposite direction and vice versa
- ask patient to move jaw vertically and push upwards
- pain = tenderness when palpated
What is the origin of the medial pterygoid?
deep head = medial surface of the lateral pterygoid plate
superficial head = tuberosity of the maxilla
What is the insertion of the medial pterygoid?
medial surfaces of the angle of the mandible
What is the action of the medial pterygoid?
elevate and assist protrusion of the mandible
How do you examine the medial pterygoid?
no reliable way to palpate or test this muscle
Which muscle can cause trismus if contacted during IDB?
medial pterygoid
Describe the movements of the TMJ.
- rotation = initial opening, rotation of the condyle, hinge movement
- translation = wider opening, sliding movement
- when the mandible protrudes, the condyles leave their fossae, and move along the articular eminences
- when the mandible retracts, the condyles leave the eminences and move back to their fossae
What is Posselt’s envelope of motion?
- range of motion of the mandible
- sagittal view of the maximum mandibular movement
Name the suprahyoid muscles.
- digastric
- mylohyoid
- geniohyoid
- stylohyoid
Name in the infrahyoid muscles.
- sternohyoid
- omohyoid
- thyrohyoid
- sternothyroid
Which muscles assist in the depression of the mandible?
- digastric
- mylohyoid
- geniohyoid
- lateral pterygoid
Which facial muscles are involved in the control of bolus?
- orbicularis oris
- buccinator
