The Vocal Organs.
No sounds touch the heart like those of the human voice, for no
mechanic, however scientific and skilful, has ever been able to make an
instrument which could produce sounds as beautiful, tones as varied, a
timbre as melodious, and inflexions as manifold and agreeable. It has
been compared to'wind, reed and stringed instruments. In touching
expression, it is most resembled by the concertborn, the bassoon, and
the hautboy. Vocal sounds, past all question, are produced in the
larynx, but these sounds are grouped, or formed into articulate speech,
by the pharynx, the nasal cavities, the tongue, the teeth, etc.
The Larynx is a kind of cavity or tube at the top of the windpipe,
formed by the union of five cartilages, namely, the thyroid, the
cricoid, the two arytenoid, and the epiglottis. Ligaments bind these
together, and muscles move them. The Thyroid Cartilage is composed of
two parts, and has a con. nection with the bone of the tongue above, and
with the cricoid Cartilage below.
The Cricoid Cartilage is shaped like a ring, and hence its Greek name. It is narrowest in front, and broadest behind. It connects with the thyroid cartilage above, and with the first ring of the trachea below. Fig. 40 gives a side view of the cartilages of the larynx: 1, bone at the base of the tongue (os hyoides) : 2, the ligament connecting hyoid bone and the thyroid cartilage; 3, the front of the thyroid cartilage; 4, the thyroid cartilage ; 6, the cricoid cartilage; 7, the wind pipe.
FIG. Fig. 41 is a back view of FIG. 41. the cartilages and ligaments of the larynx: 1, is the back surface of the epiglottis; 3, 3, the os hyoides; 4, 4, the lateral ligaments connecting the os hyoides and the thyroid cartilage; 5, 5, the back face of the thyroid cartilage; 6, 6, the arytenoids cartilages; 7, the cricoid cartilage; 8, the first ring of the windpipe. The Arytenoids Cartilages are upon the back part 'of the cricoid, and are connected with the thyroid cartilage by the vocal cords. The Epiglottis is a fibrocartilaginous lid, shaped like a leaf, which covers the upper opening of the larynx. It is connected by a cartilage to the bone of the tongue (os hyoides) and to the thyroid carti. lage. Breathing opens and shuts it; and in swallowing, it closes down upon the top of the larynx, to prevent food and drink from passing down the windpipe.
The Vocal Cords are two ligaments, formed of elastic and parallel
fibers, enclosed in a fold of mucous membrane. They are about two
lines in width, and inserted behind into the anterior projection of the
arytenoids cartilages, and passing forward, are fixed to the anterior
angle of the thyroid. There are four ligaments crossing the larynx, two
superior and two inferior, the latter being called vocal cords. The
interval between them is the glottis. The ligaments themselves are
sometimes called the lips of the qlottis. The depression between the
superior and inferior ligaments is the ventricle of the larynx.
Fig. 42 represents a view of the larynx
From above: a, b, c, the thyroid cartilage, enclosing the ring of the cricoid; A, A, e, e, the arytenoid cartilages connected by the transverse arytenoid muscle; i, i, the vocal cords ; o, o, the cricoarytenoid ligaments. The muscles which are attached to the cartilages have the power of pulling them about so as to change in various ways the shape of the laryngeal cavity; to enlarge or diminish the size of the glottis; and to relax or tighten the vocal cords. By these means, and some others, the sounds of the voice receive their various modifications. Tightening the cords, for example, raises the pitch.
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