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vocal cords are nine in number, and take their names from their points of origin and insertion, viz. : the two crico-thyroid, two thyro-arytenoid, two posterior crico-arytenoid, two lateral crico-arytenoid, and one arytenoid muscles.

The crico-thyroid muscles, by their contraction, render the vocal cords more tense by drawing down the anterior portion of the thyroid cartilage and approximating it to the cricoid, and at the same time tilting the posterior portion of the cricoid and arytenoid cartilages backward.

The thyro-arytenoid, by their contraction, relax the vocal cords by drawing the arytenoid cartilage forward and the thyroid backward.

The posterior crico-arytenoid muscles, by their contraction, rotate the arytenoid cartilages outward and thus separate the vocal cords and enlarge the aperture of the glottis. They principally aid the respiratory movements during inspiration.

The lateral crico-arytenoid muscles are antagonistic to the former, and by their contraction rotate the arytenoid cartilages so as to approximate the vocal cords and constrict the glottis.

The arytenoid muscle assists in the closure of the aperture of the glottis.

The inferior laryngeal nerve animates all the muscles of the larynx, with the exception of the crico-thyroid.

Movements of the Vocal Cords.—During respiration the movements of the vocal cords differ from those occurring during the production of voice.

At each inspiration, the true vocal cords are widely separated, and the aperture of the glottis is enlarged by the action of the crico-arytenoid muscles, which rotate outward the anterior angle of the base of the aryte. noid cartilages; at each expiration the larynx becomes passive; the elasticity of the vocal cords returns them to their original position, and the air is forced out by the elasticity of the lungs and the walls of the thorax.

Phonation. As soon as phonation is about to be accomplished a marked change in the glottis is noticed with the aid of the laryngoscope. The true vocal cords suddenly become approximated and are made parallel, giving to the glottis the appearance of a narrow slit, the edges of which are capable of vibrating accurately and rapidly; at the same time their tension is much increased.

With the vocal cords thus prepared, the expiratory muscles force the column of air into the lungs and trachea through the glottis, throwing the edges of the cords into vibration.

The pitch of sounds depends upon the extent to which the vocal cords are made tense and the length of the aperture through which the air passes. In the production of sounds of a high pitch the tension of the vocal cords becomes very marked, and the glottis diminished in length. When grave sounds having a low pitch are omitted from the larynx, the vocal cords are less tense and their vibrations are large and loose.

The quality of voice depends upon the length, size, and thickness of the cords, and the size, form, and construction of the trachea, larynx, and the resonant cavities of the pharynx, nose, and mouth.

The compass of the voice comprehends from two to three octaves. The range is different in the two sexes, the lowest note of the male being about one octave lower than the lowest note of the female; while the highest note of the male is an octave less than the bighest note of the female.

The varieties of voices, e.g., bass, baritone, tenor, contralto, mezzosoprano, and soprano, are due to the length of the vocal cords, being longer when the voice has a low pitch, and shorter when it has a high pitch.

Speech is the faculty of expressing ideas by means of combinations of sounds, in obedience to the dictates of the cerebrum.

Articulate sounds may be divided into vowels and consonants. The vowel sounds, a, e, i, o, u, are produced in the larynx by the vocal cords. The consonantal sounds are produced in the air passages above the larynx by an interruption of the current of air by the lips, tongue, and teeth ; the consonants may be divided into: (1) mutes, b, d, k, p, t, c, g; (2) dentals, d, j, s, t, z; (3) nasals, m, n, ng; (4) labials, b, p, f, v, m; (5) gutturals, k, g, c, and g hard; (6) liquids, l, m, n, r.

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REPRODUCTION.

Reproduction is the function by which the species is preserved, and accomplished by the organs of generation in the two sexes.

GENERATIVE ORGANS OF THE FEMALE. The Generative Organs of the Female consist of the ovaries, Fallopian tubes, uterus, and vagina.

The Ovaries are two small, ovoid, flattened bodies, measuring one inch and a half in length and three-quarters of an inch in width ; they are situated in the cavity of the pelvis, and imbedded in the posterior layer of the broad ligament; attached to the uterus by a round ligament, and to the extremities of the Fallopian tubes by the fimbriæ. The ovary consists of an external membrane of fibrous tissue, the cortical portion, in which are imbedded the Graafian vesicles, and an internal portion, the stroma, containing blood vessels.

The Graafian Vesicles are exceedingly numerous, but situated only in the cortical portion. Although the ovary contains the vesicles from the period of birth, it is only at the period of puberty that they attain their full development. From this time onward to the catamenial period there is a constant growth and maturation of the Graafian vesicles. They consist of an external investment, composed of fibrous tissue and blood-vessels, in the interior of which is a layer of cells forming the membrana granulosa ; at its lower portion there is an accumulation of cells, the proligerous disc, in which the ovum is contained. The cavity of the vesicle contains a slightly yellowish, alkaline, albuminous fluid.

The Ovum is a globular body, measuring about the lig of an inch in diameter; it consists of an external investing membrane, the vitelline membrane; a central granular substance, the vitellus or yelk; a nucleus, the germinal vesicle, in the interior of which is imbedded the nucleolus, or germinal spot.

The Fallopian Tubes are about four inches in length, and extend outward from the upper angles of the uterus, between the folds of the broad ligaments, and terminate in a fringed extremity which is attached by one of the fringes to the ovary. They consist of three coats: (1) the external, or

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