1. The _thyroid cartilage_ is the largest cartilage of the larynx, and consists of two four-cornered cartilaginous plates held together in front and diverging behind; the anterior borders are convex, and consequently where the two plates meet in front they form an upper and a lower notch or slit. The posterior angles of this cartilage extend into the so-called horns of the _thyroid cartilage_. At the upper horns are ligaments attached, which form the connection between the hyoid bone and the larynx, while the lower horns serve to join the thyroid to the cricoid cartilage. In females and boys the angle formed by the two plates of the _thyroid cartilage_ is obtuse. In the male sex at a certain period the larynx changes its shape, and the plates of the _thyroid cartilage_ then form an acute angle, which is visible on the outside of the throat, and is popularly known as the _Adam's apple_. At this time the diameter of the male larynx becomes a third larger than that of the female larynx, and in consequence the voice is lower, and its different registers are more enlarged in compass. 2. The _cricoid cartilage_ resembles in shape a seal ring; its broader side is situated posteriorly between the lower horns of the _thyroid cartilage_, and it is connected by its lower edges immediately with the upper edge of the first ring of the trachea. From its side at the back part project two rounded surfaces, which give attachment to the _arytenoid cartilages_. 3. The _arytenoid cartilages_ are two small but very mobile bodies in the form of three-cornered pyramids. The base of the pyramid rests upon the before-mentioned rounded surface at the back of the upper border of the _cricoid cartilage_; one of its sides turns to the front, the two others to the back and outwards. The surfaces between the anterior and postero-interior corners are accordingly turned towards one another. The surface posteriorly is concave, and affords space for a part of the _arytenoid muscle_; the inner surface is smooth, and forms, during quiet breathing, a part of the lateral wall of the larynx; the anterior surface is rough and irregular, and to it adhere the _vocal chords_, the _thyro-arytenoid muscle_, the _lateral and posterior crico-arytenoid muscles_, and upon these the bases of the _cuneiform cartilages_. The _arytenoid cartilages_ are lengthened at their summits by two little pear-shaped elevations, the _cartilages of Santorini_ (called _apophyses_ in Garcia's observations), which are connected with them by ligamentous fibres, and extend with them some distance into the larynx. 4. The _cartilages of Wrisberg_ are described by Hyrtl as slight elevations upon the front or anterior edge of the _arytenoid cartilages_, inclining towards the interior, and, like all parts of the larynx, covered by the mucous membrane.