530: 1 (CG)

Laryngeal function

1. Airway protection: cough, swallow, regulation of airflow

2. Abdominal fixation: lifting heavy objects, childbirth, defecation

3. Phonation

Voice Production

A multi-system process involving the respiratory system (power), laryngeal system (source), and articulatory/resonance system (filter)

Hyoid bone

U-shaped; only unpaired bone in the body; attachment point for suprahyoid and infrahyoid musculature

Thyroid cartilage

Comprised of two flat plates (laminae); fused in the front with a notch at the top; thyroid notch is visible in some people as the "Adam's apple"; posterior plates have horns

Horns of thyroid cartilage

Superior horns loosely articulate with the posterior hyoid bone via the thyrohyoid membrane; inferior horns articulate with the posterior cricoid cartilage via the cricothyroid joint; joint allows rocking, rotation, and gliding of thyroid cartilage over cricoid cartilage

Cricoid cartilage

Signet ring-shaped; forms the base of the larynx; sits atop the trachea; has articular facets for thyroid and arytenoid cartilages, creating the cricothyroid and cricoarytenoid joints

Arytenoid cartilages

Paired, small pyramid-shaped cartilages that sit on the posterior top of the cricoid cartilage; vocal folds attach to them, allowing gross vocal fold movement; abduction = opening, adduction = closing

Vocal process

The vocal ligament and thyrovocalis attach to the arytenoids at the vocal process

Muscular process

The thyromuscularis, lateral cricoarytenoids, and posterior cricoarytenoids attach to the arytenoid via the muscular process

Corniculate cartilages

Paired cartilages that sit atop the superior surface of the arytenoid cartilages; serve no major role in voice function

Cuneiform cartilages

Paired cartilages embedded within the aryepiglottic folds; provide structure and support for the laryngeal membrane

Epiglottis

Leaf-shaped cartilage rooted into the top of the thyroid cartilage; covers the opening of the larynx during swallowing; deflects food/liquid into the esophagus and away from the larynx and trachea; third layer of airway protection during swallowing

Intrinsic musculature

Connects the laryngeal framework to itself; origin and insertion of each muscle are within the larynx; responsible for vocal fold movement and posturing

Extrinsic musculature

Connects the larynx to other parts of the body; has one point of attachment to the larynx; includes suprahyoids and infrahyoids; responsible for laryngeal movement within the neck and vertical laryngeal position

Intrinsic muscles of the larynx

Lateral cricoarytenoid; posterior cricoarytenoid; thyroarytenoid (thyrovocalis and thyromuscularis); cricothyroid; oblique and transverse interarytenoids

Lateral cricoarytenoid

Adducts the medial portion of the vocal folds via movement of the arytenoid cartilages; applies medial compression to the vocal folds for strong glottic closure

Interarytenoids

Includes oblique and transverse muscles; adducts the posterior portion of the vocal folds via movement of the arytenoid cartilages; closes the posterior glottis

Posterior cricoarytenoid

The only intrinsic muscle responsible for vocal fold abduction (opening)

Abduction

Breathing; vocal folds are open; primary muscle is the posterior cricoarytenoid

Adduction

Speaking, singing, phonation, coughing, and swallowing; vocal folds come together and vibrate; muscles include lateral cricoarytenoid and interarytenoids

Thyroarytenoid

Includes thyrovocalis (medial portion) and thyromuscularis (lateral portion); deepest layer of the vocal folds; isometrically contracts to shorten and thicken the vocal folds; increases vocal fold mass

Cricothyroid

Stretches, lengthens, and thins the vocal folds; increases longitudinal tension/stiffness; decreases vocal fold mass; responsible for elevating pitch

Muscular antagonists

Thyroarytenoid and cricothyroid

Extrinsic muscles of the larynx

Suprahyoid and infrahyoid muscles

Suprahyoid muscles

Elevate the hyoid bone and larynx; include digastric, stylohyoid, geniohyoid, and mylohyoid

Infrahyoid muscles

Depress the hyoid bone and larynx; include sternohyoid, sternothyroid, thyrohyoid, and omohyoid