The Larynx is the origin of sound production and acts as the Vibrator of the Vocal Instrument. It is sometimes referred to as the “voice box”, alluding to its purpose. It is responsible for protecting the air-way from foreign substances like food and liquid, which could interfere with our ability to breath if allowed into the lungs, and even cause death. So, although the Larynx is the “Voice” and is strongly associated with sound production, its more critical function is guardian of the trachea and lungs.
The Larynx is suspended in the front of the neck at the top of the Trachea, which it connects to the Pharynx as part of the Respiratory System. When we swallow the Larynx is pulled up, closing the true and false Vocal Cords and is covered by the Epiglottis. This closing action prevents swallowed material from entering the Larynx and reaching the Lungs, instead being forced down the Esophagus. When this function fails, the Larynx, in combination with the Breathing muscles, is responsible for the cough reflex to expel the food particles that got through.
The secondary function of the Larynx, and the one we are mainly concerned with here, is that of sound production. The Larynx is the mechanism that houses the Vocal Cords (Folds) and the Muscles and Cartilages that coordinate their function. The structure of the Larynx is mainly defined by the Thyroid Cartilage, the Hyoid Bone, and the Cricoid Cartilage.
During the act of phonation, either for speaking or singing, the Vocal Folds are approximated, (brought close together) by the adduction of the Arytenoid Cartilages. This is accomplished by the Arytenoid and Cricoarytenoid Muscles, the Lateral which bring the Arytenoids together, and the Posterior which separate the Arytenoids. The Cricothyroid Muscles are responsible for lengthening and stretching the Vocal Folds, through a rocking motion of the Thyroid Cartilage, for higher pitch associated especially with the upper register. The Thyroarytenoid Muscle, also termed the Vocalis, is the muscle that appears as the body of the Vocal Fold. Running parallel and connected to the Vocalis is the Vocal Ligament, also Thyroarytenoid Ligament, which is the material that actually comes in contact during Phonation.