At the top of the trachea, and seeming a part of it, is the cricoid cartilage, which is almost circular. It resembles a signet ring, the broad surface being at the back.

Above the cricoid cartilage is the thyroid cartilage, which forms the front and sides of the larynx. This consists of two lateral cartilaginous plates joined in front at an acute angle. These plates are widely apart behind. The posterior edge of each is continued in upper and lower horns on either side. The upper horns are connected with the hyoid bone. The lower horns are connected with the cricoid cartilage by means of a joint which allows one surface to move freely on the other.

small triangular pyramids that rest upon the upper edge of the back part of the cricoid cartilage at the back of the larynx. Each cartilage articulates with the cricoid cartilage by means of a joint which allows freedom of motion.

1. Epiglottis.

2. Thyro-hyoid ligament.

3. Thyroid cartilage.
4. Cricoid cartilage.

5. Hyoid bone.

6. Superior horn of thyroid cartilage.
7. Crico-thyroid muscle.
8. Trachea.

The anterior angle of the base of each arytenoid cartilage unites with the posterior end of a vocal cord, and is one of

the most important means of changing the tension of the vocal cords.

The cartilages of Santorini are two small cartilages at the apex of each arytenoid cartilage.

The cartilages of Wrisberg are two small cartilages found in the folds of membrane between the apex of each

FIG. 6.-The Vocal Cords.
1. Vocal cord.

2. Arytenoid cartilage.

3. Thyro-arytenoid muscle.
4. Connective tissue.

5. Thyroid cartilage.

6. Hyoid bone.

7. Glottis.

8. Esophagus.

arytenoid cartilage and the sides of the epiglottis.

The epiglottis is a leafshaped cartilage between the root of the tongue and the larynx. During respiration or vocalization the epiglottis is raised, but during the process of swallowing it closes tightly over the larynx.

THE MUSCLES AND THE LIGAMENTS OF THE LARYNX. The vocal cords are two ligaments in the membranous lips within the larynx. Near the edge of each lip, just within the covering of mucous membrane, is stretched a band of glistening white elastic fibres. These two bands are attached to the angle of the thyroid cartilage, in front, and to the anterior angles of the bases of the arytenoid cartilages at the back of the larynx.

The vocal cords of men are longer than the vocal cords of women. Those of men are a little over a half-inch in length; those of women, less than a half-inch.

The opening between the vocal cords is called the glottis. Just above the vocal cords are little cavities called ventricles. Just above the ventricles are fleshy edges called

false vocal cords, or ventricular folds. The false vocal cords are the lower edges of membrane extending from the sides of the epiglottis in front to the arytenoid cartilages at the back.

1. The thyro-hyoid ligament connects the thyroid cartilage with the hyoid bone.

2. The crico-thyroid muscle extends from the front of the cricoid cartilage to the lower horns of the thyroid cartilage, and connects the cricoid and thyroid cartilages.

3. The thyro-arytenoid muscles lie next to the vocal cords, attached at one end to the thyroid cartilage, and at the other end to the arytenoid cartilages. They are attached to the vocal cords by tiny fibres, and in this way modify the action of the cords.

4. A mesh of muscles lies next to the thyro-arytenoid muscles, and connects them with the walls of the thyroid cartilage.

5. The arytenoid muscle lies at the back of the larynx, and joins the arytenoid cartilages. This indirectly modifies the tension of the vocal cords.

6. The posterior crico-arytenoid muscles run from the back or "signet" of the cricoid cartilage to the outer angle of the arytenoid cartilages.

7. The lateral crico-arytenoid muscles run from the outer angles of the arytenoid cartilages to the upper part of the cricoid cartilages.

8. The depressor of the epiglottis is attached to the epiglottis and arytenoid cartilage.

THE CAVITIES OF RESONANCE

The cavities of resonance are the trachea, the two ventricles, the pharynx, the mouth, the two nares, and the eight sinuses.

The trachea is the cavity of resonance for tones low in pitch. It extends from the larynx to the lungs.

The ventricles, or small cavities above the voice lips, are the cavities in which the vibrations of the cords are trans

mitted to the air. They modify the tone but little.

The pharynx is the cavity extending from the larynx to the nares. Its sides and posterior surface are covered with highly elastic muscles, and these in turn are covered with mucous membrane. By contracting and expanding, the muscles vary the size and shape of this cavity, and so modify the tone. For beautiful tone, these muscles should be relaxed. The pharynx serves principally to direct or project tone.

The mouth is the resonant cavity that varies most in size

and shape during the production and molding of tone. This is due to the mobility of the tongue and soft palate. The tongue is composed of muscles running in every direction, and it is capable of almost infinite variety of position.

It is attached at its root to the hyoid bone, and for the greater part of its length it is attached below to the lower jaw. The palate, or covering of the mouth cavity, consists of two parts, the hard or bony palate, and the soft palate or velum. The soft palate is very elastic. Sometimes it is perfectly relaxed, as in breathing, and shuts the pharynx off from the mouth. In tone production and speech the soft palate rises and presses back against the pharynx, thus closing the opening into the upper pharynx. In the head tones, the soft palate pushes up into the upper pharynx.

The parts of the soft palate important in the voice work are the uvula, or pendent portion, and the muscular bands at the sides called the pillars of fauces. These help to form the transient cavities that mold tone.

The nasal cavities extend from the base of the cranium to the roof of the mouth. The anterior portions, opening at the face, are called nostrils. The posterior portions, opening at the back into the pharynx, are called nares. The two nares are separated by a thin partition, called the septum. In each of the nares the convolutions of the ethmoid bone produce three fissures, known as the upper, middle, and lower meatus. These fissures resound or re-enforce the tones high in pitch. It has been discovered that the overtones of the vocal cords are re-enforced in the nares.

Each of the nares communicates with four small cavities, called sinuses-the frontal above in the forehead, the sphenoidal behind, and the maxillary and ethmoidal on either side. When tone is held a moment in the nares, it will resound in the sinuses also. In this way tone is further re-enforced, and the voice becomes more resonant.