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TO REVIEW
SKELETAL STRUCTURE OF LARYNX
6 Cartilages:
Cricoid
Thyroid
Arytenoid
Corniculate
Cuneiform
Epiglottic
1 Bone:
Hyoid
Basic Structure/Layers of Vocal Folds:
Epithelium
Lamina Propria
Thyroarytenoid (Vocalis) Muscle
Cricoid Cartilage (Anterior)
Thyroid Cartilage (Anterior)
Arytenoid, Corniculate, and Cuneiform Cartilages
Epiglottic Cartilage (Anterior, then Sagittal)
Hyoid Bone (Anterior)
MOVING ON....
INTRINSIC LARYNGEAL MUSCLES: All Paired
Arytenoid Muscles
Interarytenoids (transverse, oblique)
Thyroarytenoid Muscles
Cricoarytenoid Muscles (posterior, lateral)
Cricothyroid Muscles
INTRINSIC LARYNGEAL MUSCLES:
All innervated by recurrent laryngeal nerve
Except: Cricothyroids innervated by external
branch of superior laryngeal nerve
Intrinsic Muscles Anterior-Superior View
Intrinsic Muscles Posterior-Superior View
INTRINSIC MUSCLES: OPENING & CLOSING THE FOLDS
INTRINSIC MUSCLES: CLOSERS/ADDUCTORS
Lateral Cricoarytenoids (LCA)
Interarytenoids (IA)
Transverse
Oblique
INTRINSIC MUSCLES: OPENERS/ABDUCTORS
Posterior Cricoarytenoids (PCA)
Pull the arytenoids laterally to open
the glottis
INTRINSIC MUSCLES: LENGTHENING AND SHORTENING THE FOLDS
INTRINSIC MUSCLES: LENGTHENERS/THINNING
Pitch/Frequency of voiced sounds is largely controlled by varying the
length of the vocal folds. As the folds are lengthened, their mass per unit
length is reduced. Consequently, they vibrate faster when lengthened.
The vocal folds are attached to the thyroid cartilage at the front and
the arytenoid cartilage at the back. The arytenoid cartilage, however,
rides on the cricoid cartilage. So the length of the folds is mainly
achieved by using the Cricothyroid (CT) Muscles, which rock the
cricoid cartilage backward and upward, causing rotational
movement of the thyroid cartilage (moving it slightly forward and
tipping its front end downward). The cricothyroid muscles also pull
the arytenoid cartilages slightly backwards, as they ride on the
cricoid cartilage. These movements enabled by the cricothyroid
muscles both lengthen and thin the vocal folds.
INTRINSIC MUSCLES: LENGTHENERS/THINNING
INTRINSIC MUSCLES: SHORTENERS/THICKENING
Shortening of the vocal folds occurs when the
thyroarytenoid muscles (TA) contracts. When the
thyroarytenoid muscles are not opposed by the
thyrocricoid muscles (the lengtheners), they exert a
shortening-thickening-laxing influence on the vocal
fold cover tissues.
TO RECAP:
Openers/Abductors: PCA
Closer/Adductors: LCA & IA
Lengtheners: CT
Shorteners: TA
IMPORTANT TO REMEMBER:
The Lengtheners/Shorteners and
Openers/Closers all work in
constant relationship to each
other.
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