Outline Larynx Dr. Bennett-Clarke General remarks

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Dr. Bennett-Clarke

General remarks

The larynx is also called the “voice box” or the organ of speech.

-The superior part of the trachea

• It acts to hold the airway open

• Anteriorly covered by strap muscles (Infrahyoid muscles) and thyroid gland

• Adjacent to C3-C6

• Visible on the surface of the neck as the laryngeal prominence
I. Skeleton of the larynx –is composed of the cartilages (Hyaline with the exception of one) and membranes (all of it is covered with mucous membrane).

A. Cartilages of the laryngeal skeleton- 3 paired and 3 unpaired


1. Thyroid cartilage- largest

 Incomplete posteriorly

 Composed of 2 laminae or plates joined at midline

Form laryngeal prominence = larger in males

***All laryngeal cartilages bigger in males

- Superior horn = attachment to the hyoid bone

In thyrohyoid membrane and attached to lesser horn of hyoid

- Inferior Horn  forms a synovial joint with the cricoids cartilage

= Important in movement of vocal ligament

2. Cricoid cartilage- complete ring

 Only complete ring

Signet ring appearance

Lateral Facet = articulation with inferior horn of thyroid

Posterior Facet = Articulation with Arytenoid Cartilages

3. Epiglottic- leaf-shaped, fibroelastic elastic cartilage

Inferior point attached to internal midline of thyroid cartilage


  1. Arytenoid cartilages- pyramidal shape  Rest on posterior superior margin of cricoid cartilage

    1. Muscular (lateral) process = attach intrinsic muscles of the Larynx

    2. Vocal Process = attachment of vocal ligaments (cords)

2. Corniculate cartilages

Attached on apex of Arytenoids

3. Cuneiform cartilages

Paired and found in the aryepiglotic fold (which is mucous membrane)

B. Membranes and ligaments of the laryngeal skeleton


  1. Thyrohyoid membrane: Does not make a complete circle

    1. From Inferior hyoid & superior thyroid

    2. Any structure that acts on the hyoid will act on the larynx

    3. Pierced by internal Laryngeal nerve & Superior Laryngeal artery

  2. Cricothyroid membrane: Can only see on the anterior side & is thickened

    1. Sometimes called median cricothyroid ligament

    2. Runs from inferior thyroid to superior cricoid arch

    3. Goes into the larynx

    4. Lateral Cricothyroid ligament = forms the conus elasticus

  3. Cricotracheal membrane: Attaches larynx to the trachea


  1. Quadrangular membrane: quadrangular shaped membrane from the lateral margins of the epiglottis to the anterolateral margin of the arytenoid cartilages

    1. Creates a canal/opening for the larynx

    2. Free Superior margin = Aryepiglotic fold

    3. Free Inferior margin = forms the false vocal folds or vestibular folds

2.Conus elasticus  Lateral portion of cricothyroid ligament/membrane

 Stretches up to the vocal ligament on the interior of the larynx

a. Vocal ligament (cords)  thickened superior aspect of conus elasticus

- Covered by mucous membrane to create Vocal Folds

*** Vestibular fold (Immovable) is superior to the Vocal fold (Movable)

II. Chambers on the interior of the larynx- The entire larynx is covered by mucous membrane, inside and out. The mucous membrane stretches over all of the cartilages and the membranes that form the skeleton of the larynx. On the inside the folds of mucous membrane divide the larynx into chambers or regions.
Rima glottidis: Space between vocal ligaments
** See diagram for the location of the following:

1. vestibule  Space above the vestibular folds

2. vestibular folds

3. ventricle  Membranous out pocketing between the vestibular folds & vocal folds

4. vocal folds

5. infraglottic cavity  below the vocal folds will continue as the trachea

***Areas used for descriptive purposes

III. Muscles of the larynx

A. Extrinsic—These muscle are responsible for moving the entire larynx via the hyoid.

Include infrahyoid muscles, suprahyoid muscles and muscles of the pharynx.

  • Action of suprahyoid muscles  Elevate the hyoid/larynx

  • Action of infrahyoid muscles  Depress the hyoid/larynx

***Epiglottis will be deflected by posterior 1/3rd of tongue as the larynx is elevated
B. Intrinsic- This is group of paired muscle which act on the vocal ligaments

Four actions of vocal ligaments & All covered with mucous membrane

  1. Abducted (Open) – for air passage

  2. Adduct (close) – involved in helping forming sound by passing air past them

  3. Tense – Allow us to produce high frequency sounds

  4. Loosen – Allow us to produce low frequency sounds

*** Abduct & Adduction = from pivoting & gliding of Arytenoid cartilages
Origin and insertion not important – actions are most important

  1. Posterior cricoarytenoid – Abduct by pulling posteriorly on muscular processes

    1. Is the only abductor

2. Lateral cricoarytenoid – Adduct by pulling forward on muscular process

3. Transverse and oblique arytenoids – Cause gliding to pull arytenoids back together to finish adduction
4. Thyroarytenoid – Thyroid cartilage rocks back & decreases vocal ligament tension

5. Cricothyroid – Thyroid cartilage rocks forward & increases vocal ligament tension

IV. Blood supply to the larynx

Subclavian artery  Thyrocervical trunk  Inferior Thyroid artery  Inferior Laryngeal artery

External Carotid  Superior Thyroid  Superior Laryngeal artery

V. Innervation to the larynx

1. Motor: Vagus, CN X

A. External Laryngeal Nerve = to Cricothyroid Muscle

B. Recurrent Laryngeal Nerve = Rest of the Intrinsic muscle of larynx

2. Sensory: Vagus, CN X

A. Above the vocal folds = Internal Laryngeal Nerve

B. Below the vocal folds = Inferior Laryngeal Nerve from Recurrent Laryngeal Nerve

C. Parasympathetic

 Internal Laryngeal Nerve has parasympathetics to mucous membrane to vocal fold

Inferior Laryngeal Nerve has parasympathetics to mucous membrane below fold

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