Laryngeal Muscles Quiz

Phonation in Speech Production

• Phonation is the process of producing sound at the larynx level.
• It's the foundation of speech, as vocal fold vibrations generate the primary sound source.
• This sound is then shaped by articulation and resonance in the vocal tract to create understandable speech.
• Sound production happens when air from the lungs passes through the glottis (space between vocal folds), causing the vocal folds to vibrate.

Structures Involved in Sound Production

• Larynx: Houses the vocal folds; central to sound production.
• Vocal Folds: Flexible layered structures; made of muscle and connective tissue that vibrate to produce sound.
• Cricoarytenoid Joints: Allow vocal folds to move (abduction and adduction).
• Laryngeal Muscles: Control vocal fold movement, including abduction (moving vocal folds apart) and adduction (bringing them together).
  • Posterior Cricoarytenoid Muscles: Responsible for abduction.
  • Lateral Cricoarytenoid and Arytenoid Muscles: Facilitate adduction.
  • Cricothyroid Muscles: Control vocal fold lengthening and tension.
  • Thyroarytenoid Muscles: Adjust vocal fold contact and tension (shortens).

What Makes a Voice Unique?

• Individual differences in vocal fold structure (thickness, length, elasticity) influence pitch and tone.
• Vocal tract configuration (shape and size of oral and pharyngeal cavities) determines resonance and timbre.
• Phonation dynamics relates to variations in the force and coordination of vocal fold movements during speech sound production.
• Habitual use, and technique shape voice quality and tone over time.

Laryngeal Cartilages (Paired and Unpaired)

• Unpaired: Epiglottis, Thyroid cartilage, Cricoid cartilage (ring)
• Paired: Arytenoid cartilages, Corniculate cartilages

Hyoid Bone

• The only "floating" bone in the body; located in the neck, between the mandible (lower jaw) and the larynx
• Suspended in place by muscles and ligaments.
• Functions include support of the tongue, assisting in swallowing, aiding speech production, and helping maintain a stable airway in the neck.
  • Body (central part)
  • Greater horns (two curved projections backward)
  • Lesser horns (two smaller projections extending upwards).

Laryngeal Joints, Ligaments, and Membranes

• Cricothyroid Joints: Articulation between cricoid and thyroid cartilages, allowing for rotation and gliding (primary motion).
• Intrinsic Ligaments and Membranes: Connect laryngeal cartilages.
  • Thyroepiglottic ligament: Connects the thyroid cartilage to the epiglottis.
  • Quadrangular membrane: Connects epiglottis, thyroid, arytenoid, and corniculate cartilages. Thicken at the bottom to become ventricular ligaments.
  • Ventricular ligament: Thickened base of the quadrangular membrane.
  • Conus Elasticus: Connects cricoid, arytenoid, and thyroid cartilages. Gives rise to middle cricothyroid ligament and lateral cricothyroid membranes, and vocal ligaments.
• Extrinsic Ligaments and Membranes: Connect laryngeal cartilages to outside structures.
  • Hyoepiglottic ligament: connects hyoid bone to epiglottis
  • Cricotracheal membrane: connects cricoid cartilage to tracheal rings
  • Hyothyroid membrane: connects hyoid bone to thyroid cartilage.
• Cricoarytenoid joints: rocking and gliding of the arytenoid cartilage

Laryngeal Cavities and Internal Regions

• Laryngeal Cavity: Extends from the cricoid cartilage to the laryngeal aditus (entrance).
• Includes important regions including the arytenoid, corniculate cartilages, sides of the epiglottis, and aryepiglottic folds.
• Laryngeal Vestibule: Upper region (laryngeal vestibule) is bounded by the ventricular folds below and laryngeal aditus above.
• Lower Region: Lower region is bounded by the bottom of the cricoid cartilage below and the vocal folds above.

Vocal Fold Layers

• Vocal folds have 5 layers:
  • Epithelium: squamous cells
  • Superficial Lamina Propria: Few elastic fibers
  • Intermediate Lamina Propria: Many elastic fibers
  • Deep Lamina Propria: Many collagen fibers
  • Muscle: Muscle fibers (thyrovocalis)

Vocal Fold Parts

• Vocal folds have membranous and cartilaginous portions

Laryngeal Muscles

• Intrinsic muscles (attachments inside the larynx):
  • Thyroarytenoids (thyrovocalis and thyromuscularis)
  • Posterior Cricoarytenoids (abduction)
  • Lateral Cricoarytenoids (adduction)
  • Transverse arytenoids (adduction)
  • Oblique arytenoids (adduction)
  • Cricothyroid (lengthening)
• Extrinsic muscles (one attachment inside and one outside the larynx):
  • Sternothyroid, thyrohyoid, inferior and superior constrictors.
• Supplemental muscles (attachments outside the larynx): - Geniohyoid, hyoglossus, omohyoid , stylohyoid, digastric

Vocal Fold Vibration, Stiffness, and Mass

• Vibration involves rapid opening and closing of the vocal folds, creating sound waves.
• Vocal fold stiffness relates to tension and elasticity of the tissues; affects pitch and quality.
• Effective mass refers to the vibrating portion; affects sound production.

Laryngeal Control Variables

• Laryngeal Opposing Pressure (LOP): Pressure created by laryngeal muscles to keep vocal folds closed; controls voice quality and intensity.
• Laryngeal Airway Resistance (LAR): Resistance to airflow through the larynx; influences voice quality; depends on adduction, the size and shape of the glottis.

Glottal Size and Configuration

• Glottal size and shape affect the characteristics of the glottis (space between vocal folds).