Henry Gray (18251861). Anatomy of the Human Body. 1918.
the middle line is connected to the cricoid cartilage by the middle cricothyroid ligament.
The posterior border, thick and rounded, receives the insertions of the Stylopharyngeus and Pharyngopalatinus. It ends above, in the superior cornu, and below, in the inferior cornu. The superior cornu is long and narrow, directed upward, backward, and medialward, and ends in a conical extremity, which gives attachment to the lateral hyothyroid ligament. The inferior cornu is short and thick; it is directed downward, with a slight inclination forward and medialward, and presents, on the medial side of its tip, a small oval articular facet for articulation with the side of the cricoid cartilage.
During infancy the laminæ of the thyroid cartilage are joined to each other by a narrow, lozenge-shaped strip, named the intrathyroid cartilage. This strip extends from the upper to the lower border of the cartilage in the middle line, and is distinguished from the laminæ by being more transparent and more flexible.
The Cricoid Cartilage (cartilago cricoidea) is smaller, but thicker and stronger than the thyroid, and forms the lower and posterior parts of the wall of the larynx. It consists of two parts: a posterior quadrate lamina, and a narrow anterior arch, one-fourth or one-fifth of the depth of the lamina.
The lamina (lamina cartilaginis cricoideæ; posterior portion) is deep and broad, and measures from above downward about 2 or 3 cm.; on its posterior surface, in the middle line, is a vertical ridge to the lower part of which are attached the longitudinal fibers of the esophagus; and on either side of this a broad depression for the Cricoarytænoideus posterior.
The arch (arcus cartilaginis cricoideæ; anterior portion) is narrow and convex, and measures vertically from 5 to 7 mm.; it affords attachment externally in front and at the sides to the Cricothyreiodei, and behind, to part of the Constrictor pharyngis inferior.
On either side, at the junction of the lamina with the arch, is a small round articular surface, for articulation with the inferior cornu of the thyroid cartilage.
The lower border of the cricoid cartilage is horizontal, and connected to the highest ring of the trachea by the cricotracheal ligament.
The upper border runs obliquely upward and backward, owing to the great