Tommy Cunningham, age 12, of Santa Cruz, Calif., for his question:
CAN YOU EXPLAIN THE LARYNX?
The larynx is a hollow chamber in which the voice is produced. It is located in the front or upper part of the windpipe of mammals, frogs and toads. The larynx is also called the voice box.
In mammals, the larynx leads from the lower portion of the pharynx to the trachea and is situated in front of or ventral to the esophagus, behind the skin and connective tissue of the throat. The larynx is supported by ligaments from the hyoid bone at the base of the tongue.
The skeletal structure of the larynx is made up of three large cartilaginous structures: the epiglottis, thyroid cartilage and cricoid cartilage. There are also several pairs of small cartilages, the most important of which are known as arytenoid cartilages.
The epiglottis is a broad cartilage attached in front to the top of the thyroid cartilage. The epiglottis swings over the opening from the pharynx into the voice box.
A person's voice is produced by two flexible ligaments attached to the sides of the larynx which vibrate when air is forced through the larynx from the lungs. These two ligaments, called vocal cords, are really folds of tissue that convey vibrations to the column of air. This resonates through the chambers of the pharynx, mouth and nasal passages.
The rate of vibrations of the folds is controlled by a number of factors, including their elasticity and the tension of their muscular structure. The faster the vibrations, the higher the voice.
The narrowest air passage in the larynx is the glottis. When the glottis widens, and the muscles are held at a relatively low tension, the voice is low. When the glottis is nearly closed and the muscles are stretched tightly, the voice produces its highest sounds.
Most men have larger larynxes and longer vocal folds than women, and as a result have deeper voices. When a boy grows into manhood, the larynx get larger and his voice lowers.
The degree to which the cords vibrate (amplitude), the amount of air passing through the glottis, and the force of the air determine whether the voice is loud or soft.
The epiglottis is a leaf shaped fibrous cartilage that folds over the glottis to protect it during the act of swallowing. The thyroid cartilage of the larynx is the lump in the front of the neck that we call the Adam's apple.
Actually, the Adam's apple has only a symbolic relation to Adam, the biblical first man. It is so called because the root of the Hebrew word "adam" can be traced back to a word meaning a body protuberance. Another Hebrew word of identical spelling, though of different meaning, was used for the man Adam. This led to the erroneous conclusion that the Adam's apple, or larynx, was named for the forbidden fruit Adam tasted in the Garden of Eden.
Air passes down from the larynx to the trachea, or windpipe, which leads to the lungs. Inflammation of the larynx is called laryngitis. Usually it is caused by infection, but it may be caused by food or other particles lodged in the larynx.