part_of part of part of develops from embryonic structure pharyngeal arch 1 lingual swellings median lingual swelling During the third week of embryological development there appears, immediately behind the ventral ends of the two halves of the mandibular arch, a rounded swelling named the tuberculum impar, which was described by His as undergoing enlargement to form the buccal part of the tongue. More recent researches, however, show that this part of the tongue is mainly, if not entirely, developed from a pair of lateral swellings which rise from the inner surface of the mandibular arch and meet in the middle line. The site of their meeting remains post-embryonically as the median sulcus of the tongue. The tuberculum impar is said to form the central part of the tongue immediately in front of the foramen cecum, but Hammar insists that it is purely a transitory structure and forms no part of the adult tongue[WP, Gray's]. VHOG:0000730 The thyroid initially develops caudal to the tuberculum impar . This embryonic swelling arises from the first pharyngeal arch and occurs midline on the floor of the developing pharynx, eventually helping form the tongue as the 2 lateral lingual swellings overgrow it. [http://emedicine.medscape.com/article/845125-overview] tuberculum impar SCTID:308821003 FMA:312476 median tongue bud tuberculum linguale mediale EMAPA:17187 EHDAA2:0001081 median lingual swelling UBERON:0006756 Wikipedia:Tuberculum_impar