Henry Gray (18251861). Anatomy of the Human Body. 1918.
and vocal ligaments, the upper portion extends between the arytenoid cartilage and the epiglottis and is often poorly defined; the lower part is a well-marked membrane forming, with its fellow of the opposite side, the conus elasticus which connects the thyroid, cricoid, and arytenoid cartilages to one another. In addition the joints between the individual cartilages are provided with ligaments.
The Conus Elasticus (cricothyroid membrane) is composed mainly of yellow elastic tissue. It consists of an anterior and two lateral portions. The anterior part or middle cricothyroid ligament (ligamentum cricothyreoideum medium; central part of cricothyroid membrane) is thick and strong, narrow above and broad below. It connects together the front parts of the contiguous margins of the thyroid and cricoid cartilages. It is overlapped on either side by the Cricothyreoideus, but between these is subcutaneous; it is crossed horizontally by a small anastomotic arterial arch, formed by the junction of the two cricothyroid arteries, branches of which pierce it. The lateral portions are thinner and lie close under the mucous membrane of the larynx; they extend from the superior border of the cricoid cartilage to the inferior margin of the vocal ligaments, with which they are continuous. These ligaments may therefore be regarded as the free borders of the lateral portions of the conus elasticus, and extend from the vocal processes of the arytenoid cartilages to the angle of the thyroid cartilage about midway between its upper and lower borders.
An articular capsule, strengthened posteriorly by a well-marked fibrous band, encloses the articulation of the inferior cornu of the thyroid with the cricoid cartilage on either side.
Each arytenoid cartilage is connected to the cricoid by a capsule and a posterior cricoarytenoid ligament. The capsule (capsula articularis cricoarytenoidea) is thin and loose, and is attached to the margins of the articular surfaces. The posterior cricoarytenoid ligament (ligamentum cricoarytenoideum posterius) extends from the cricoid to the medial and back part of the base of the arytenoid.
The thyroepiglottic ligament (ligamentum thyreoepiglotticum) is a long, slender, elastic cord which connects the stem of the epiglottis with the angle of the thyroid cartilage, immediately beneath the superior thyroid notch, above the attachment of the ventricular ligaments.
Movements.The articulation between the inferior cornu of the thyroid cartilage and the cricoid cartilage on either side is a diarthrodial one, and permits of rotatory and gliding movements. The rotatory movement is one in which the cricoid cartilage rotates upon the inferior cornua of the thyroid cartilage around an axis passing transversely through both joints. The gliding movement consists in a limited shifting of the cricoid on the thyroid in different directions.
The articulation between the arytenoid cartilages and the cricoid is also a diarthrodial one, and permits of two varieties of movement: one is a rotation of the arytenoid on a vertical axis, whereby the vocal process is moved lateralward or medialward, and the rima glottidis increased or diminished; the other is a gliding movement, and allows the arytenoid cartilages to approach or recede from each other; from the direction and slope of the articular surfaces lateral gliding is accompanied by a forward and downward movement. The two movements of gliding and rotation are associated, the medial gliding being connected with medialward rotation, and the lateral gliding with lateralward rotation. The posterior cricoarytenoid ligaments limit the forward movement of the arytenoid cartilages on the cricoid.
Interior of the Larynx (Figs. 953,954).The cavity of the larynx (cavum laryngis) extends from the laryngeal entrance to the lower border of the cricoid cartilage where it is continuous with that of the trachea. It is divided into two parts by the projection of the vocal folds, between which is a narrow triangular fissure or chink, the rima glottidis. The portion of the cavity of the larynx above the vocal folds is called the vestibule; it is wide and triangular in shape, its base or anterior wall presenting, however, about its center the backward projection of the tubercle of the epiglottis. It contains the ventricular folds, and between these and the vocal folds are the ventricles of the larynx. The portion below the