Anatomy of Phonation

Introduction

  • Discussion about anatomy of phonation

  • Importance of having access to the Bio Digital Human App and worksheets

Definition of Phonation

  • Phonation refers to the process of making noise involving:

    • Cartilages

    • Bones

    • Nerves

    • Considered a regulatory system

Overview of the Larynx

  • Functionality: Primarily responsible for protection and respiration, but also plays a crucial role in speech as an overlay function.

  • Location: The larynx is located deep in the tissues of the neck and is situated atop the trachea.

  • Components: Composed of a series of cartilages that provide structure and support.

Main Components of the Larynx

  • Cricoid Cartilage: Sits immediately on top of the trachea.

  • Thyroid Cartilage: Articulates with the cricoid and is important in sound production.

  • Arytenoid Cartilages: Positioned on the posterior cricoid cartilage.

  • Vocal Ligament: Connects arytenoid cartilages to thyroid cartilage.

  • Lateral Cricoarytenoid Muscle: Responsible for closing the vocal folds.

Mechanism of Phonation

  • Formation of Speech: Initiated by:

    • Airflow from the lungs and trachea.

    • Bringing the vocal folds together.

  • Vocal Fold Movement:

    • When folds come closer, air pressure drops, causing folds to be sucked into the airstream.

    • This leads to opening and closing cycles powered by subglottal air pressure and Bernoulli effect.

  • Vocal Fold Vibration:

    • Seen to open from bottom to top and close from bottom to top, contributing to voice acoustics.

Physiology of the Lungs

  • Voice production powered by airflow from the lungs.

  • Understanding inspiratory and expiratory muscles helps to regulate airflow during phonation.

  • Control over pitch, volume, and stress patterns is essential for voicing.

Anatomy of Phonation

  • Vocal Mechanism: Located in the larynx with the vocal folds being key components.

  • Biological Functions of the Larynx: Includes:

    • Airway protection

    • Lifting

    • Coughing

  • Non-biological Functions: Producing sound sources and shaping speech.

Vocal Tract Regions

  • Glottis: The space between the vocal folds.

  • Supraglottal Region: Area above the glottis.

  • Subglottal Region: Area below the glottis.

Structural Overview of the Larynx

  • Bones and Cartilages: Include:

    • Hyoid Bone:

    • Only bone in the larynx region; connects muscles.

    • Thyroid Cartilage:

    • Anterior and posterior ridges important for voice production.

    • Cricoid Cartilage:

    • Circular and helps to articulate with arytenoid cartilages.

  • Unpaired vs Paired Cartilages:

    • Includes Thyroid, Cricoid, Arytenoid, and Epiglottis (unpaired) and Corniculate and Cuneiform (paired).

Cartilages of the Larynx

  • Thyroid Cartilage:

    • Provides structure for vocal folds.

  • Cricoid Cartilage:

    • Circular in shape; connects with thyroid and arytenoid carriages.

  • Epiglottis:

    • Protects airway during swallowing.

  • Arytenoid Cartilages:

    • Integral for vocal fold attachment and movement.

  • Corniculate and Cuneiform Cartilages:

    • Support and stiffen the aryepiglottic folds.

Muscles of the Larynx

  • Categorization:

    • Intrinsic: Both origin and insertion within the larynx.

    • Extrinsic: One attachment in the larynx and one outside.

    • These support and fixate the larynx.

    • Suprahyoid: Elevate hyoid bone and larynx, inserting above the hyoid bone.

    • Infrahyoid: Depress hyoid bone and larynx, inserting below the hyoid bone.

Key Muscles Discussed

  • Thyrohyoid Muscle:

    • Origin: Oblique line of thyroid cartilage.

    • Insertion: Greater cornu of hyoid bone.

    • Function: Elevation of the larynx.

    • Innovation: Spinal nerve C1.

  • Digastric Muscle:

    • Composed of anterior and posterior muscles.

    • Anterior Origin: Inner surface of mandible, inserts into the hyoid via intermediate tendon.

    • Function: Elevates the hyoid bone.

    • Innovation: Trigeminal nerve V.

  • Stylohyoid Muscle:

    • Origin: Styloid process of temporal bone; insertion at corpus of hyoid bone.

    • Function: Elevate and retract hyoid.

  • Geniohyoid Muscle:

    • Origin: Inner surface of mandible; insertion at hyoid bone.

Summary

  • Review of laryngeal structures, functions, and musculature for phonation.

  • Introduction to assessment methods including worksheets and app for hands-on learning.