Larynx or Voice Box or Glottis
Larynx lies above wind pipe (trachea) in the neck and in front of the food pipe (oesophagus). It is the passageway for air between pharynx above and trachea below.
It produces sound for speaking and singing.
Larynx allows the air breathe to pass in and out of the lungs (air passage from pharynx to the rest of respiratory track).
Larynx grow larger in male, it's sticks out at front of throat, called Adam's apple.
Structure Associated with Larynx
Superiorly - Hyoid bone and root of tongue
Inferiorly - continuous with the trachea
Anteriorly - muscle attached to hyoid bone and muscles of neck
Posteriorly - laryngopharynx and 3rd to 6th cervical vertebrae
Laterally - lobe of the thyroid gland
Structure of Larynx
Larynx is triangular shape structure. The structure of larynx formed by irregular shaped cartilages attach to each other by membranes, ligaments, cartilage.
Cartilages of Larynx
There are 9 cartilages present. Out of 9 cartilage, 3 are paired cartilage and 3 are unpaired cartilage.
Three paired smaller cartilages are-
1. Arytenoid cartilage
2. Corniculate cartilage
3. Cuneiform cartilages
Larynx is composed of 3 large unpaired cartilage-
1. Thyroid cartilage
2. Cricoid cartilage
3. Epiglottis cartilage
3 Unpaired Cartilage of Larynx
1. Thyroid Cartilage
Thyroid cartilage (forms adam's apple) is most prominent and largest cartilage.
It consist of right and left laminae (plate or layer). It is flat piece of hyaline cartilage.
Thyroid cartilage form the anterior wall of larynx and give triangular shape.
Posterior border of each lamina is extended upward and downwards to form the processes called "superior" and "inferior" cornua or horns.
Superior cornua connected with greater cornua of hyoid bone by lateral thyrohyoid ligament.
Inferior cornua joint with cricoid cartilage to form "cricothyroid joint"
Upper part of thyroid cartilage is lined with stratified epithelium like larynx.
Lower part thyroid cartilage is lined with ciliated columnar epithelium like trachea.
Larynx is supported above thyroid cartilage by ligaments (thyrohyoid membrane) connected to the hyoid bone.
2. Cricoid Cartilage
Cricoid cartilage is nost inferior cartilage of larynx. Below the thyroid cartilage is cricoid cartilage.
Ring of cartilage that connect thyroid cartilage with trachea below.
Cricoid is attached to first ring of the cartilage of trachea by "cricotracheal ligament"
Cricoid cartilage is connected to thyroid cartilage by cricothyroid ligament.
Cricoid broad posterior part joint with arytenoid cartilage above, and with inferior cornua of thyroid cartilage below. It is lined with ciliated columnar epithelium.
3. Epiglottis/Epiglottic Cartilage
Epiglottis is a flap of cartilage that covers the glottis when swallowing.
It helps to prevent food and liquid from entering the trachea and lungs.
Long leaf shaped flap of elastic cartilage.
It's lower end attached to inner surface of anterior wall of thyroid cartilage immediately below the thyroid notch.
It is covered with stratified squamous epithelium.
Leaf portion is free to move up and down.
Epiglottis folds down over the opening (called glottis) into the larynx during swallowing and swing back up.
3 Paired Cartilage of Larynx
1. Arytenoid Cartilage
Arytenoid are two roughly pyramid shaped cartilages
Situated on top of the border part of cricoid cartilage forming part of posterior wall of larynx.
They give attachement to vocal cords and to the intrinsic pharyngeal muscles.(responsible for sound production)
Supported by arytenoid cartilage, instrinsic pharyngeal muscle contract and thus move vocal cords.
Arytenoid cartilage are lined with ciliated columnar epithelium.
2. Two Corniculate Cartilage
Horn shaped cartilage
Rest on top of each arytenoid cartilage
3. Two Small Cuneiform Cartilage
Rod shaped
Elastic cartilage located near base of epiglottis
Supported the vocal cords
Cavity of Larynx - Laryngeal Cavity
Cavity of the larynx lined by mucus membrane.
Cavity of larynx extends from laryngeal inlet at epiglottis to the circular outlet at lower border of cricoid cartilage where it is continuous with the lumen of trachea.
Mucus membrane lining the larynx forms two pair of folds, that divided into 3 divisions-
1. Vestibular fold (False vocal cords)
2. True vocal cords/ fold
1. Vestibular Fold or False Vocal Cords
Upper pair of folds called false vocal cords.
Space between vestibular folds called "Rima vestibuli"
No part in produce sound, vestibular folds function in holding the breath against pressure in thoracic cavity.
2. True Vocal Cords
Lower pair of fold is vocal cords or true vocal cords.
Slit like space between true vocal cords called "Rima glottidis"
True vocal cords and space between them are together called "glottis"
Divisions of Cavity of Larynx
Vestibular and vocal fold divide the cavity of larynx into 3 parts-
1. Vestibule - division of laryngeal cavity above false vocal cords.
2. Ventricle - very short middle portion (between vestibular and vocal folds).
3. Infraglottic larynx - below the laryngeal ventricles and rima glottidis.
Function of Larynx
1. Airway function
2. Voice production
3. Protection of airway (epiglottis protect)
4. Warming, filtering and humidifying
5. To protect airway from chocking on material in throat
6. Expulsion of contaminants from the lungs
7. Regulate flow of air into lungs
8. Generation abdominal pressure
7. Phonation/production of sound
8. Articulation (formation of clear and distinct sound in speech)
9. Speech, pitch, volume, tone
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