Lecture 5: Physiology of Jaw, Lips, and Tongue Movement

Question 1

How is jaw movement and muscle function different during speech and swallowing?

Answer 1

• Less movement of mandible for speech than for chewing
• Lateral movements are especially small
• Horizontal motion is greater than in chewing
• Masseter and temporalis less active during speech than medial pterygoid
• Anterior belly of digastric is very active during speech
• Chewing:
  
  • Agonists (work in direction of movement) and antagonists (work in direction opposite movement) not co-contracting
• Speech:
  
  • More variable activation patterns, agonists and antagonists co-contracting is common

Question 2

What are the differences between: EMG, electropalatography, strain gauges, LED, nasal endoscopy, and X-ray?

Answer 2

EMG

• Measurement of muscle action potential
• Indicates muscle activation, not the movement of the structures
• Various bellies within the mm
• Motor units
• Difficult to record EMG from one mm in the lip region or the tongue due to fiber interdigitization

ELECTROPALATOGRAPHY

• A palate is made of acrylic and lectrodes are embedded in the palate
• Electrodes sense tongue contact and record that to a computer
• May interfere with normal articulation, and does not detect contact on linguaveolar or posterior palatal contact well

STRAIN GAUGES

• Movement of the structures causes electrical signals to be generated
• Used for the study of lip and jaw movements, respiratory kinematic movements

LED

• Light-emitting diodes are attached to articulators and tracked by a receiver

NASAL ENDOSCOPY

• Camera used to visually assess movement
• Can be used to assess velopharyngeal closure patterns

X-RAY

• Still x-rays of a speech posture
• Moving x-rays (fluoroscopy) of moving speech structures
• Can be used to assess VP function in running speech
• Microbeam equipment
• Attach radio-dense markers to articulators
• Can assess movements of speech structures with little radiation to speaker