sheath of thyroid gland

sheath of thy·roid gland

covering of the thyroid gland external to its capsule formed by a splitting of the pretracheal layer of deep cervical fascia at the gland's posterior border; the anterior lamina covers the gland anterolaterally, attaching to the arch of the cricoid cartilage superior to the isthmus of the gland (causing it to move with the trachea during elevation/depression of the larynx); the posterior lamina passes posterior to the esophagus to blend with the buccopharyngeal fascia; inferiorly, the sheath extends along the inferior thyroid veins to open into the superior mediastinum (hence, expansion of the thyroid, as by goiter, can take this direction).
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