Larynx and Vocal Cords
The larynx is an organ in the neck associated with swallowing and sound (voice) production. The larynx is located at the point where incoming air (inspirational air) is directed to the trachea leading to the lungs, and where incoming food is routed into the esophagus for passage to the stomach.
The location and design of the larynx allows it to protect the airway from inadvertently routed food. The larynx is also commonly called the "voice box," in recognition of its crucial role in the formation of speech. The design of the larynx allows it to produce the sounds that comprise speech. As well, the design and location of the larynx play a role in the control of air movement during breathing.
The larynx is a tubular chamber about two inches high. The walls of the larynx are made of a tough material called cartilage bound by ligaments and membranes. The cartilaginous larynx rests on another piece of cartilage called the cricoid. Immediately below the cricoid begin the rings of the trachea. Immediately above the larynx lies a U-shaped structure called the hyoid. The larynx extends out of the trachea, which is easily detected in males as the "Adam's apple."
A pair of vocal cords (also known as vocal folds) lies at the center of the larynx. The vocal cords are essentially bands of muscle with a structure called the arytenoid at the center of each cord. The arytenoid has many muscles attached to it. They supply the muscular power that moves the larynx. During silent breathing the muscles are relatively slack, allowing the vocal cords to lie along the walls of the larynx. This orientation leaves the air passage open. During speech, contraction of the arytenoid muscles pulls the vocal cords are brought close together and are folded into a closed position across the larynx. Air passing by the vocal cords vibrates each cord, which produces a sound. An analogy is the vibration of the reed on a wind instrument like the oboe. Various muscles can adjust the tension of the vocal cords and the space between, to produce sounds of various pitches. The tauter the cords, the higher the pitch. Modification of the sound by the throat, tongue and lips produces recognizable speech.
The larynx is rich in nerves and so is very sensitive to touch. This permits the larynx to respond very quickly to any unintended material that touches it, such as food. A reflexive cough expels the material.
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