The<unk>  connects together the lower thirds of the lobes; it measures about 1.25 cm. in breadth, and the same in depth, and usually covers the second and third rings of the trachea.
Its situation and size present, however, many variations.
In the middle line of the neck it is covered by the skin and fascia, and close to the middle line, on either side, by the Sternothyreoideus.
Across its upper border runs an anastomotic branch uniting the two superior thyroid arteries; at its lower border are the inferior thyroid veins.
Sometimes the<unk>  is altogether wanting.
Thyroid isthmus
Lingual thyroid
Parathyroid gland
Palatine tonsil
Hypophysial fossa
Bone island
Thyroid gland
Parotid duct