What we term “vocal cord” is often compared to the edge of a string when viewed from above during vibration and this is possibly where the term cord came from. I also frequently see the term “vocal chord” though I believe chord is a mis-spelling as the vibrating portion of the larynx does not generally represent the straight line portion of a curve nor three musical notes, both definitions refering to a "chord".
Viewed in cross section though, the vocal cord doesn’t look like a cord at all. It is more of a wedge in shape. Still, musically it does function like a cord and many analogies to a cord or string, such as a comparison to the string on a guitar, can be made.
Some people call them “vocal folds,” which is a more apt description of their three dimensional visual appearance. They are each a fold of soft tissue rising from the edges of the airway. However, the terms vocal cord and vocal fold can be, and are, used interchangeably.
The vocal cord is essentially a muscle under a ligament with mucosa covering both of them. A layer of lubricant, the lamina propria, lies between the mucosa and the ligament-muscle combination. The muscle tightens and loosens to change the pitch of the vibrations. The lubricating layer allows the mucosa on the surface to vibrate easily. The muscle may oscillate to a small degree, like a string on a guitar or piano, but the lining on the surface is the primary oscillator or generator of sound. The mucosa is like a layer of silk draped over the edge of the ligament and the mucosa vibrates when air passes rapidly by it.
When we examine sound production, we will be able to establish typical configurations of the glottis for each of these problems. The vocal cords have two general positions: ABducted and ADducted. When ABducted, they are apart and in the configuration of a V.
When ADducted the vocal cords should come essentially into near alignment, often almost parallel to each other. The lungs generate pressure below and air can then be passed through the vocal cords from the windpipe below. As air passes through this narrow slot between the vocal cords, the mucosa starts to vibrate, creating sound.
Let’s define how the vocal cords produce sound when all is normal.