History and Examination for Thyroid Nodules

The name thyroid gland, in English, is derived from the Latin glandula thyreoidea, meaning shield-shaped gland, named by Thomas Warton in 1656 [1]. As the first endocrine gland to develop embryologically [2], it possesses important functions from fetal development until death. Embryologically, the development of the thyroid gland begins in the fourth week of development as a depression and epithelial thickening of the floor of the primitive pharynx. Beginning at the base of the foramen caecum, the thyroid primordium descends into the underlying mesenchyme and travels through the neck as a bilobed diverticulum. The gland arrives at its final resting place in front of the trachea in the seventh week [2, 3]. During the descending process, the thyroid gland remains connected to the tongue surface by a thyroglossal duct from which it will eventually detach. The thyroglossal duct typically regresses and disappears; however, in around 50% of the population, the distal portion of the thyroglossal duct persists as a pyramidal lobe of the thyroid (Fig. 2.1) [5]. A thyroglossal duct cyst, the most common congenital neck mass, seen in around 7% of the population, is a remnant dilation of the thyroglossal duct between the foramen caecum and the thyroid gland which did not fully regress [4, 6]. Postpartum: The thyroid gland’s final anatomical location is anterior to the trachea and caudal to the thyroid cartilage. The adult thyroid gland consists of a right