The Probert Encyclopaedia of Medicine

LARYNX

The larynx is the organ (voice-box) at the entrance to the trachea (windpipe) in the front of the neck. It is the organ by which the voice is produced. The larynx is enclosed by cartilages. Below it is supported by a firm ring, the cricoid cartilage, which is the entrance to the trachea proper. The much larger thyroid cartilage is perched on top of the cricoid. It is shaped like a snow-plough, with its two halves widely separated behind and meeting in front to form the Adam's apple.

The mucous membrane which lines the larynx is thrown into various folds. These folds are called the true vocal cords, and by their movements the voice is produced. They are called true, as distinct from the false vocal cords which are above them, but take no part in producing the voice.

The true vocal cords projecting towards the middle form a chink, which is called the glottis. By the contraction of various muscles this chink can be so brought together that the air forced through it throws the edges of the membrane into vibration and so produce sounds. Variations in the form of the chink will affect changes in the sound. Thus the production of voice is the same as in musical
instruments, the arrangements in the larynx being such as to produce (1) the vibratory sounds, (2) to regulate the sound, (3) to vary the pitch, and (4) to determine the quality of the sound. The rapid, delicate, muscular movements involved are produced by nervous stimuli reaching the muscles from the brain. Thus the voice is produced in the larynx, and is modified by the rest of the respiratory passages. In the act of swallowing, the glottis is covered by a cartilaginous plate called the epiglottis.
Research Larynx