The most inferior part of the laryngeal cartilages and completely encircles the trachea. It is shaped like a signet ring with a broad lamina of cricoid cartilage posteriorly and a much slimmer arch of cartilage anteriorly completing the circle.
The lamina has two depressions separated by a vertical ridge. There are two articular facets on each side for articulation with other laryngeal cartilage. The superior facets are for articulation with the arytenoid cartilages. The other facets are on the lateral surface for articulation with the inferior horn of the thyroid cartilage.
Part of the larynx which is both a valve to close the lower respiratory and an instrument to produce sound.
It also acts as an attachment point for muscles and ligaments. The esophagus attaches to the ridge of the lamina surface while the crico-arytenoid muscle attaches into the depressions.
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