NCIt definition : The narrow, central portion of the thyroid gland that crosses the trachea anteriorly
and connects the lateral lobes of the gland. When present, the normal variant pyramidal
lobe may extend from the isthmus.;
Alternative definition : CDISC: The narrow, central portion of the thyroid gland that crosses the trachea anteriorly
and connects the two lobes of the gland. (NCI);