Larynx Anatomy, Function, and Voice Disorders: A Comprehensive Guide

What is the larynx?

The structure that forms an air passage from the lungs to the pharynx and is the main part of the phonatory system.

What is the function of the larynx?

It produces sound, protects the airway, and coordinates the airway during swallowing.

Where is the larynx located?

It extends from the inferior border at the cricoid cartilage to the superior border where it opens into the pharynx, located between C3 and C6.

What is the cricoid cartilage?

The only complete cartilaginous ring of the larynx, located at its inferior border.

What is the thyroid cartilage?

It forms the anterior and lateral walls of the larynx and includes the laryngeal prominence known as the Adam's apple.

How does the thyroid cartilage change in males during puberty?

It enlarges and tilts forward and down, causing vocal folds to lengthen and thicken, resulting in a lower pitch.

What is the epiglottic cartilage?

A leaf-shaped cartilage that protects the airway, especially during swallowing.

How is epiglottic cartilage kept moist?

Made up of epithelial cells that secrete mucous

What are valleculae?

Depressions in the mucosa between the median and lateral glossoepiglottic folds, important in feeding and swallowing.

Where does food or liquid sometimes get stuck?

Valleculae

What is the hyoid bone?

A horseshoe-shaped bone that provides the framework for the larynx, supports the tongue, and is not connected to any other bone.

What is the role of laryngeal membranes?

They link the cartilages of the larynx to each other and to surrounding structures, forming folds when covered by mucous membrane.

What are the two classifications of laryngeal muscles?

Extrinsic muscles, which attach within and outside the larynx, and intrinsic muscles, which are entirely contained within the larynx.

What is the primary function of the cricothyroid muscle?

It is responsible for changing the pitch of the voice.

Which nerve innervates the cricothyroid muscle?

The superior laryngeal nerve.

What is the recurrent laryngeal nerve responsible for?

It innervates most intrinsic laryngeal muscles, except for the cricothyroid muscle.

What branches of the vagus nerve are responsible for innervation of the intrinsic laryngeal muscles?

Superior laryngeal nerve- innervates cricothyroid

Recurrent laryngeal nerve- innervates the rest

What may damage to the superior laryngeal nerve cause?

Change in pitch

What is the significance of the left recurrent laryngeal nerve's length?

It loops under the aorta, while the right loops under the subclavian artery, but this does not affect muscle timing.

What are ventricular folds?

Also known as false vocal folds, they are higher up in the larynx and serve a supportive role in phonation and airway protection.

What is the difference between abduction and adduction of the vocal folds?

Abduction is moving the vocal folds away from each other, while adduction is bringing them together.

What is the paramedian position of the vocal folds?

It is the position where the glottis is open for resting breathing.

What is the pyriform sinus?

An area where food may pocket during swallowing.

What anatomical differences exist between pediatric and adult airways?

In children, the tongue is larger in proportion to the mouth, and the epiglottis, hyoid, and glottis are more compressed.

What is the significance of the epiglottis in infants?

The tip of the epiglottis contacts the soft palate when supine, facilitating 'obligate nasal breathing' and a 'suck-swallow-breathe' pattern.

What is sound defined as in voice physiology?

Sound is the variable disturbance of pressure between molecules and a medium, capable of traveling through any medium.

How is acoustic energy described?

The disturbance of air molecules that transfers energy, traveling in longitudinal waves from one air molecule to another.

What does frequency refer to in voice physiology?

The number of completed cycles of vibration per second, perceived as pitch.

What is the difference between low pitch and high pitch?

Low pitch corresponds to fewer vibrations per second, while high pitch corresponds to more vibrations per second.

What are pure tones and complex tones?

Pure tones are single frequencies, while complex tones are two or more pure tones blended together.

What is subglottic pressure?

The pressure of air underneath adducted vocal folds, crucial for vocal fold vibration.

What is the myoelastic aerodynamic theory of phonation?

It describes how vocal folds adduct to create resistance to air, and subglottic pressure overcomes this resistance to create vibration.

What is the Cover Body Model in vocal fold vibration?

It suggests that vocal folds vibrate in a wave-like fashion from top to bottom, creating asymmetry in pressure that maintains vibration.

What is the glottal fry?

The lowest portion of the vocal range, characterized by a popping sound at around 50Hz.

What is the modal register?

The mid-frequency range at which most people normally speak.

What factors influence loudness in voice?

Influenced by subglottic pressure and the amount of air passing through the glottis.

What are the two main categories of causes for voice disorders?

Functional causes (related to environment, use, habit, personality/emotion) and organic causes (related to lesions, injury, mass, disease).

What is happening in the VF when pitch is high?

Increased length and decreased mass

What is happening in the VF when pitch is low?

Decreased length and increased mass

What are vocal fold nodules?

The most common benign lesions, usually bilateral, occurring along the mucosa of the vocal folds due to vocal abuse

What is laryngeal carcinoma?

The growth of abnormal cells in the larynx, with poorer outcomes if it crosses the midline.

What is a polyp?

Another benign lesion of the vocal folds

More blister like

Have more sudden onset

Tend to be unilateral

Reddish in colour

What is subglottic stenosis?

The narrowing of the subglottic airway, usually congenital, causing stridor and hoarseness.

What is laryngomalacia?

A condition in infants characterized by a floppy airway, leading to stridor that worsens when lying down.

What is the impact of mass lesions on voice?

Mass lesions can lower vocal pitch, cause asynchronous vibration, diplophonia, and result in a harsh or hoarse voice quality.

What is diplophonia?

Double voice- two vibrations at once

What does breathiness indicate?

VFs can’t fully adduct?

What does hoarsness indicate?

VFs can’t adduct evenly

What is ventricular dysphonia?

Occurs when false vocal folds are used instead of true vocal folds, resulting in lower pitch and diplophonia.

What is vocal fold paralysis?

The total loss of mobility of vocal folds due to damage to the Vagus nerve (recurrent and superior laryngeal branches), which can be unilateral or bilateral.

What is the significance of vocal fold paralysis being bilateral?

• Bilateral indicates damage higher in the CNS (before separation of 2 branches)

• If bilateral and fixed in midline: requires tracheostomy

• If bilateral and fixed in abduction: risk to swallow safety

How is Parkinson's disease a phonatory pathology?

It is a neurogenic voice disorder. It is linked to hypokinetic dysarthria, which is not insufficient movement

What are the symptoms of Parkinson's disease related to voice?

Symptoms include breathiness, incomplete vocal fold adduction, rapid rushes of speech, and monopitch.

What is functional aphonia?

A voice disorder where vocal intensity is reduced to a whisper without an organic cause.

What is puberphonia?

The inappropriate use of a higher pitch in post-pubertal males.

What are examples of psychogenic voice disorder?

Functional aphonia and puberphonia.

What is the process of a psychogenic voice disorder?

Autonomic nervous system perceives 'threat' and acts accordingly by adjusting body functions. Can create physical symptoms but no organic cause.

What is webbing?

Incomplete separation of the vocal folds leaving soft tissue in the glottis (gap).

Usually during embryonic development but sometimes acquired later due to trauma, surgery, chemotherapy etc.

What is a granuloma?

A benign lesion which develops in response to irritation and is composed of specialised tissue.

On the vocal folds- it develops on medial/posterior aspects of the arytenoids.