The Hyoid bone
- U shaped bone attached at the base of the tongue
- The laryngeal structure is suspended from it
The Cricoid cartilage
- ‘Ring-like’ cartilage with an irregular shape in the posterior section
- Top cartilage of the trachea (windpipe)
- The foundation for the laryngeal structure
The Thyroid cartilage (‘Adam’s Apple’)
- Prominent V shaped cartilage in the front of the throat
- Houses and protects the vocal folds
The Arytenoid cartilages
- Two small pyramid shaped cartilages attached by ligaments atop the posterior end (back) of the cricoid cartilage
- They open and close the vocal folds
The Epiglottis cartilage
- The leaf-shaped cartilage at the top of the thyroid cartilage
- Covers the top of the trachea (specifically – covers the glottis) when eating and drinking.
There are two categories of muscles involved in laryngeal function
- Intrinsic muscles – both ends are attached inside the laryngeal structure
- Extrinsic muscles – one end is attached to the larynx and the other end is attached to some point outside of the larynx.
The Thyroarytenoid muscles (Vocal folds)
There are two sets of vocal folds
The upper set of vocal folds are referred to as either:
- The ventricular bands –OR-
- The false vocal chords
The lower set of vocal folds are referred to as either:
- The vocalis muscles –OR-
- The Internal thyroarytenoids –OR-
- True vocal chords (vocal folds)
The space between these upper and lower bands (true and false vocal folds) is called the ventricle and houses the lubricating glands for the vocal folds.
The opening or space between the two (true) vocal folds is called the glottis or the glottic aperture – when it is open for normal breathing, this space forms a triangle, but when it is open for phonating (making sound) it forms a slit.
The underside of the vocal folds is lined with a tough protective membrane called the
The vocalis muscle makes up two thirds of the length of each vocalfold while the back third is cartilaginous, consisting of the vocal process of the arytenoid cartilage.
When the vocal folds serve as a valve (for swallowing, coughing, lifting), both sets of chords (true and false) assist in closing the valve.
Only the true vocal folds are at work during phonation
The Cricothyroid muscle
- Is attached to the criroid cartilage and the lower section of the thyroid cartilage.
- When it contracts, it pulls the thyroid cartilage forward and down
- This motion results in a lengthening of the thyroarytenoid muscles which helps in the production of higher tones when singing.
The Cricoarytenoid muscles – two sets:
- The posterior cricoarytenoid muscles
- lateral cricoarytenoid muscles
The posterior cricoarytenoid muscles
- Resist the forward pull on the arytenoids by the vocals muscle
- Open the vocal folds by pulling the vocal folds out to each side.
The lateral cricoarytenoid muscles
bring the chords back together.
The Arytenoid muscles –
There are three muscles in this interarytenoid group which “connect the arytenoid cartilages and are the primary factor in bringing the back end of the vocal folds together.
The transverse arytenoid muscle –
forms a horizontal band across the back surface of the arytenoids cartilages and is the most important means of adducting the vocal folds.
A pair of oblique arytenoid muscles
- form an X across the back of the arytenoids cartilages from the top of each down to the muscular process of the other.
- They assist the transverse arytenoids muscles in pulling the arytenoids cartilages together.
- They also function in the act of swallowing and in other valving actions of the larynx.
The Supralayrngeal muscles originate above the larynx and are suspended from the hyoid bone. These muscles pull up on the laryngeal structure to:
- Aid in chewing and swallowing and are therefore also known as ‘the chewing and swallowing muscles’.
- Also aid in the tongue movements which control articulation.
The Infralaryngeal muscles
pull down on the laryngeal structure and aid in yawning and inhaling. Therefore, they are known as ‘the yawning muscles’.
The Constrictor muscles (upper, middle and lower)
- Muscles which line the throat and assist in swallowing by squeezing the food down toward and into the mouth of the esophagus.
- Because some of the muscles of the cricoid and thyroid cartilages merge with the lower constrictor muscle, the result is an important anchoring effect on the larynx during phonation.