Diseases of the Air Passages: The Larynx.

Otago Witness, Issue 2666, 19 April 1905, Page 72

Diseases of the Air Passages : The Larynx.

I. The larynx is the. organ of voice, and befora proceeding to the discussion of the diseases to which it is liable it is necessary to give a definite idea of the organ and its functions. Ie i s contained in th© prominence in front of the neck commonly known as the "Adam's Apple," which is most conspicuous in the neck of the male sex owing, no doubt, to its greater size, and due to the deeper note which the male voice produces, demanding longer cords for its production. It is a "box" of cartilage, that substance commonly known as gristle, softer thaa bone, but sufficiently hard, especially when the shape is not straight, lne B .iape of a cardboard box renders that pliable material rigid, although when it is straight it has little of theWigid character to commend it. Similarly with cartilage, the shape is essential to its rigidity. The larynx consists essentially of two rings of cartilage. They are shaped like a pair of signet rings, in which the larger one has the thin part of the ring removed. This ring is the front one (the thyroid cartilage), and it fits over the outside of the lower one, in which the signet part (broader part) is turned back (cricoid cartilage). Where they come into contact there is a joint, and if you construct such an instrument of cardboard you will see the movement of the lower parts of the two "signets" towards each other, f and vice versa. Now, if you stretch two bands between the upper edges of the two "signet - shaped cartilages they will represent the "vocal cords," and you will find that if yoti could attach muecles to the lower parts, passing from one to the other, it will be possible to stretch these "vocal cords, while muscles passing from the upper parts will slacken them. The vocal cords, however, are not really strings, but the free edge's of a membrane which stretches from either sid^, and beiween them all the air we breathe, whether we speak or not, must pass. When the cords are tight and the air passes through it produces a sound, and the character of the sound depends on the tightness of the cords their degree of approximation to each other (otherwise the narrowness of the chink between them), and the rate at which the air passes through. Suffice it to say that small cartilages of a triangular or pyramidal shape are pivoted on th« lop of the back- turned cartilage (cricoid), and lo the on (aryt&r.oid cartilages) the back part of the vocal cords is attached. Now these cartilages turn round, so that movement of them produces the approach and withdrawal of the vocal cords towards and from each other. They also yield to the tension or increase the tension of the cords, as a person fitting in a chair n.ay put his head back or forward without moving in his seat. Since all these things are reigulated' to a nicety by means of muscles controlled by nerves, guided automatically and by our intelligence, it will be obvious that it is a somewhat complicated matter, and it would be difficult to describe the arrangement, and useless, in the absence of diagTams and a goodsized working model of the organ. — Liverpool Mercury.