Variations in the number and in origin of the thyroid arteries.

The number of arteries providing blood supply for the thyroid gland as well as the origin of the superior thyroid and inferior thyroid arteries were examined in 132 fetuses from single pregnancies and in 144 fetuses from twin pregnancies, aging 4 to 9 months. Most frequently (81% cases) four thyroid arteries were observed. Five thyroid arteries were noted in 14.4% cases. Sources of additional thyroid arteries were described.