The attachments of the conus elasticus to the laryngeal skeleton: physiologic and clinical implications

The attachments of the inferior and dorsal extensions of the lateral parts of the conus elasticus (CE) are not fully understood. A re-investigation was done in plastinated serial sections of 20 adult human larynges. The CE consists of a coherent sheet of connective tissue fibers dividing into two layers toward the inferior anchorage to the cricoid arch, and the posterior anchorage to the cricoid lamina. Caudally, the medial fiber layer is continuous with the submucous fibroelastic membrane of the trachea and is not connected to the cricoid cartilage. The lateral caudal fiber layer is attached to the superior rim of the cricoid arch. Dorsally, both layers of the CE are fixed to the cricoid lamina, the lateral sheet to the lateral edge of the cartilage, the medial sheet to its anterior perichondrium near the midline. Towards the cricoarytenoid joint, the dorsal extension of the CE divides into a caudal and a cranial sheet including a fold of adipose tissue at the base of the arytenoid cartilage. The cranial layer extends towards the vocal process, the caudal layer radiates into the joint capsule and may therefore influence the complicated joint mechanics. The firm attachments of the CE to the cricoid cartilage probably counteract deformations of the CE during phonation. An insufficient fixation of the CE may contribute to an obstruction of the airways causing sleep apnea.