[Age dependence of functional systems, exemplified by the vocal cord and cricothyroid articulation]

The age dependency of functional systems is treated at the vocal cord and the cricothyroid articulation. At the time of birth there is a different developmental stage of the vocal cord. The anterior parts are essentially further differentiated than the posterior ones. The cause is to be found in the insertion of the vocal muscle at the anterior part. By intrauterine muscle contraction the polypeptide chains of the collagenous fibres are directed. The oblique cricothyroid ligament which limits the tension of the vocal cord in the cricothyroid articulation is already well developed and protects the vocal ligament from overstretching. The differences in the development balance in the first decennium. At the same time a sex-different structure of the vocal cord develops, whereby the vocal cord of the woman above all consists of elastic, the vocal cord of the man of collagenous fibres. At old age the two kinds of fibres degenerate. The cricothyroid ligament, however, does not show any involutional processes and as in early childhood fulfils its protective function.