Laryngeal Anatomy and Function

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Questions and Answers

What type of tissue primarily makes up the membranes in the larynx?

Cartilaginous tissue

Fibrous connective tissue

Epithelial tissue (correct)

Blood tissue

Which of the following ligaments connects the thyroid to the hyoid bone?

Hyoepiglottic ligament

Thyrohyoid ligament (correct)

Thyroepiglottic ligament

Cricotracheal ligament

What is the primary function of the intrinsic membranes and ligaments of the larynx?

Provide blood supply to the larynx

Protect the larynx from foreign objects

Attach the larynx to external structures

Support the larynx and vocal folds (correct)

Which layer of the vocal folds is characterized by having a basement membrane?

Squamous epithelium Signup and view all the answers

What is the subglottal pressure range typically required for normal speech?

3-5 cmH2O Signup and view all the answers

What is the primary function of the vocal folds during abduction?

They open from back to front. Signup and view all the answers

Which cartilage is the largest and made of hyaline cartilage?

Thyroid Signup and view all the answers

What type of joint is formed between the cricoid and thyroid cartilages?

Synovial joint Signup and view all the answers

What is the space located between the true vocal folds called?

Glottis Signup and view all the answers

Which of the following pairs correctly identifies a type of paired cartilage within the larynx?

Arytenoid - Corniculate Signup and view all the answers

What is the primary function of the larynx?

Protection Signup and view all the answers

What causes the vocal folds to vibrate during phonation?

Cyclic opening and closing due to air pressure Signup and view all the answers

Which of the following actions can be used to open the vocal folds for phonation?

Coughing Signup and view all the answers

What negatively affects the vocal folds when performed repeatedly?

Coughing Signup and view all the answers

In the myoelastic-aerodynamic theory, what is the role of subglottal air pressure?

It builds below the larynx and opens the vocal folds. Signup and view all the answers

How does abdominal fixation contribute to vocal fold closure?

It involves a tight closure after a large inhale. Signup and view all the answers

Which of the following describes the myoelastic phase of phonation?

Elasticity of vocal folds allows them to close. Signup and view all the answers

What is a consequence of repeated coughing for individuals who rely on phonation?

Can cause damage to vocal folds Signup and view all the answers

What is the primary function of the hyoid bone in relation to the larynx?

Attaches and provides support for the tongue and larynx. Signup and view all the answers

Which cartilage type is NOT part of the larynx?

Tracheal cartilages Signup and view all the answers

What happens during the rocking movement of the arytenoid cartilage?

The arytenoids rock upwards and outwards. Signup and view all the answers

What are the pyriform sinuses located between?

The aryepiglottic folds and thyroid cartilage. Signup and view all the answers

What is the primary purpose of the aditus laryngis?

To serve as the opening to the laryngeal cavity. Signup and view all the answers

Where are the valleculae located?

Between the tongue and epiglottis. Signup and view all the answers

Which division of the laryngeal cavity contains the vocal folds?

Ventricular division Signup and view all the answers

What is a characteristic movement of the cricoarytenoid joint?

It permits gliding and rotation for vocal fold adjustment. Signup and view all the answers

What primarily influences the fundamental frequency (FF) of vocal folds?

Age and gender Signup and view all the answers

Which muscle is responsible for abducting the vocal folds?

Posterior cricoarytenoid Signup and view all the answers

What is the effect of the cricothyroid muscle on the fundamental frequency?

Increases FF Signup and view all the answers

What occurs during the vertical phase difference of vocal fold vibration?

Vocal folds open from back to front Signup and view all the answers

Which of the following is NOT a dimension of voice quality?

Age Signup and view all the answers

Which muscles would typically depress the hyoid bone?

Sternohyoid Signup and view all the answers

What characterizes glottal fry or pulse register?

Crackly sound and reduced tension Signup and view all the answers

The termination of phonation occurs when the vocal folds are abducted, primarily caused by which muscle?

Posterior cricoarytenoid Signup and view all the answers

Which statement accurately describes the relationship between intensity and loudness?

They have a direct relationship Signup and view all the answers

In what way do the myoelastic and aerodynamic processes interact during phonation?

Airflow causes vocal fold vibration Signup and view all the answers

What is the significance of vocal jitter?

Measures cycle-to-cycle differences in vibration Signup and view all the answers

Which muscles are classified as intrinsic muscles of the larynx?

Thyroarytenoid Signup and view all the answers

Which vocal register cannot be classified as a 'true' register?

Whistle Signup and view all the answers

What is the average maximum phonation time for a typical individual?

10 seconds Signup and view all the answers

Study Notes

Infraglottic & Subglottic Division

The Bernoulli effect is a critical component of vocal fold vibration.

Membranes & Ligaments

Extrinsic membranes and ligaments attach the larynx to outer structures for stability.
- Examples include the thyrohyoid, cricotracheal, and hyoepiglottic ligaments.
Intrinsic membranes and ligaments remain within the larynx, supporting the vocal folds and connecting cartilages.
- Examples include the thyroepiglottic, cricothyroid, conus elasticus, and quadrangular membrane.
The conus elasticus is also known as the cricovocal membrane.
The true vocal folds, made up of the squamous epithelium with the basement membrane, superficial lamina propria, intermediate lamina propria, deep lamina propria, and muscle, help produce voice.
The false vocal folds are the ventricular folds.

Glottis

The glottis is the space between the vocal folds.
The glottis remains closed due to subglottal pressure and airflow, allowing voice to be maintained.
Normal subglottal pressure for speech is 3-5 cm H2O.
The average maximum phonation time is 10 seconds.
Phonation ends when the vocal folds abduct, usually due to the posterior cricoarytenoid muscle.

The Glottic Cycle

The glottic cycle consists of open and closed phases, which create the vibrations necessary for voice production.
The open phase occurs from back to front (tongue) and the closed phase occurs from front (tongue) to back.

Vibrations & Properties of Vocal Folds

Vocal fold vibrations are caused by the interaction of airflow with vocal fold tissue.
- Factors such as elasticity, stiffness, and inertia contribute to the vibration.
Elasticity refers to the vocal fold's ability to return to its original shape.
Stiffness is the vocal fold's strength, determined by its elastic properties.
Inertia is the mass or quantity of matter in the vocal fold.

Laryngeal Muscles

Extrinsic muscles connect the larynx to structures outside of it, such as the hyoid bone, sternum, and tongue.
- They function to elevate or depress the hyoid (all extrinsic muscles) or larynx (only two muscles).
Suprahyoid muscles elevate the hyoid.
- They include the mylohyoid, digastric (anterior & posterior), stylohyoid, geniohyoid, genioglossus, and hyoglossus.
Infrahyoid muscles depress the hyoid.
- They include the sternohyoid, omohyoid, sternothyroid, and thyrohyoid.
Sternothyroid and thyrohyoid are "true muscles" that depress the hyoid and move the larynx.
Intrinsic muscles connect structures within the larynx, working to change vocal fold position and tension.
- They connect laryngeal cartilages and muscles to affect vocal fold movements.

Intrinsic Laryngeal Muscles: Adductors

Lateral cricoarytenoids (2)
Oblique arytenoids (2)
Transverse arytenoid

Intrinsic Laryngeal Muscles: Abductors

Posterior cricoarytenoid

Intrinsic Laryngeal Muscles: Tensors

Cricothyroid (pars recta & oblique)
Thyrovocalis

Intrinsic Laryngeal Muscles: Relaxers

Thyromuscularis

Nerves

The superior branch of the vagus nerve (CN X) innervates the cricothyroid muscle.
The recurrent branch of the vagus nerve (CN X) innervates all other intrinsic laryngeal muscles.

Auxiliary Muscles

Superior thyroarytenoid
Thyroepiglottic
Aryepiglottic

Vocal Parameters & Properties

Fundamental Frequency (FF): The number of vocal fold vibrations per second, controlled by intrinsic muscles.
- The cricothyroid and thyrovocalis muscles increase FF.
- The thyromuscularis muscle decreases FF.
Pitch: Directly relates to frequency and is measured in Hertz (Hz).
- Determined by age and gender.
- Vocal jitter, or vocal perturbation, is the cycle-by-cycle difference in vocal fold vibration or fundamental frequency.
Intensity: Directly relates to loudness (louder = longer adduction) and is measured in decibels (dB).
- Controlled by increases in subglottal pressure, lung alveolar pressure, medial compression, and laryngeal tension.
- Vocal shimmer is the cycle-by-cycle difference in intensity.
Vocal Registers:
- Modal register (modal phonation): Used in everyday speech.
- Glottal fry (pulse register): The lowest register, producing a crackly sound due to lowered subglottal pressure and tension.
- Falsetto: Vocal folds are tensed, thin, shortened, and bowed, causing brief contact.
Other Registers:
- Whistle register: Not a true register, it occurs at a very high frequency (around 2500 Hz).
- Whisper: Not a true modal register, it doesn't involve vocal fold vibration.

Clinical Parameters

Voice quality: The subjective description of sound produced, such as hoarseness, breathy, or strained.
Pitch: The perceived highness or lowness of a voice.
Loudness/Intensity: How loud the voice is produced.
Resonance: How the sound quality is influenced by the resonating cavities of the vocal tract.
Voice disorder: When the voice does not meet daily needs.
- This can include abnormal vocal production, lack of pitch, vocal quality issues, loudness problems, or resonance issues.
Voice modification: Adjusting one's voice intentionally for various reasons.
- Example: Social culture, professional use, gender identity, etc.

Respiration & Phonation

Respiration is the source of energy for speech and phonation.
Phonation: Producing vocalization or voice, due to the cyclic opening and closing of the vocal folds.
- This process involves muscle tension and pressure (aerodynamic and muscular forces).
The vocal folds (VF) are the primary muscles of phonation.

The Larynx

The larynx is a funnel-shaped structure composed of cartilage, connective tissue, and muscle.
Primary function: Protection of airway.
Secondary function: Production of voice.

Laryngeal Functions (Non-Speech)

These functions can be both positive and negative for voice production:
- Positive functions:
  - Opening the vocal folds, often used in clinical techniques to initiate phonation when a client cannot open their vocal folds on their own.
- Negative functions:
  - Closing vocal folds, potentially leading to vocal fold damage.

Laryngeal Functions: Examples

Coughing: Involves a deep inhale, followed by vocal fold closure and increased subglottal pressure, leading to explosion of air from the lungs.
Throat clearing: Similar to coughing but with less force.
Abdominal fixation: Involves a large inhale followed by vocal fold closure.
- Used for activities like lifting weights, childbirth, and defecation.
Reflexive actions: Involuntary opening of the vocal folds in preparation for breathing.

Myoelastic-Aerodynamic Theory of Phonation

The vocal fold opening and closing, creating voice, come from the combination of:
- Myoelastic phase: The vocal folds are elastic and close due to their inherent elasticity.
- Subglottal air pressure: Pressure builds below the larynx (3-5 cm H2O) and blows the vocal folds apart.
- Aerodynamic phase: The pressure and velocity of air, influenced by the Bernoulli effect, lead to vocal fold vibration, which in turn results in voice production.

Structures of Phonation

Vocal folds/cords (true VF): Run from the arytenoid cartilage to the thyroid cartilage, and are responsible for primary vocal fold movement.
Ventricular folds (false VF): Have minor movement compared to the true vocal folds.
Glottis: The space between the vocal folds.

Abduction & Adduction of Vocal Folds

Abduction: Opening of the vocal folds, from back to front.
Adduction: Closing of the vocal folds, from front to back.
- These movements are controlled by muscular action.

Laryngeal Cartilages

Paired cartilages:
- Arytenoid: Small, pyramid-shaped cartilages.
- Corniculate: Small cartilages located on the arytenoids.
- Cuneiform: Small cartilages within the aryepiglottic folds.
Unpaired cartilages:
- Cricoid: The most inferior cartilage of the larynx, made of hyaline cartilage.
- Thyroid: The largest cartilage, made of hyaline cartilage (two fused plates).
- Epiglottis: A leaf-like, elastic cartilage that protects the airway.

Cartilage Joints

Cricothyroid joint: Connects the cricoid and thyroid cartilages, allowing for rocking and gliding movements, controlling pitch by changing vocal fold length and tension.
Cricoarytenoid joint: Connects the cricoid and arytenoid cartilages, allowing for rocking, gliding, and slight rotation, influencing the shape of the glottis.

Hyoid Bone

While not technically part of the larynx, the hyoid bone is essential for supporting the larynx and tongue. It functions as an attachment point.

Laryngeal Cavities

Valleculae: Two depressions between the tongue and epiglottis.
Pyriform sinuses: Two spaces located between the aryepiglottic folds and the thyroid cartilage.
Laryngeal cavity:
- Vestibular/superior division: The aditus laryngis, the opening of the cavity, is protected by the aryepiglottic folds.
- Ventricular/middle division: Contains the ventricular folds, vocal folds, and the glottis.
- Infraglottic/inferior division: Located below the vocal folds.

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Description

Explore the intricate details of laryngeal anatomy, including the infraglottic and subglottic divisions. This quiz covers the Bernoulli effect, ligaments, membranes, the structure of vocal folds, and the glottis. Test your understanding of how these components contribute to voice production.