Topographic anatomy and vascularization of the glandula thyroidea in rats

Topographical anatomy and detailed measurements of the glandula thyroidea (thyroid gland) and the glandula parathyroidea (parathyroid gland) were determined in rats, with significant differences identified between the sexes. In the rats (N = 10 male, 10 female), the glandula thyroidea were positioned at the level of the C1 and C2 vertebrae. One glandula parathyroidea was present in each glandula thyroidea lobe, localized in the cranial part of the lateral lobes in 60% of the animals. There was no glandula thyroidea left lobe in one female and no isthmus in two females. Both the A. thyroidea cranialis and the A. pharyngea ascendens originated from the A. carotis externa, which acted as a common trunk. On the left, the A. thyroidea caudalis originated from the truncus brachiocephalicus in all rats and on the right side was found to originate from both the truncus costocervicalis and the A. subclavia dextra in three females, and only from the truncus costocervicalis in seven females. The V. thyroidea cranialis opened into the V. jugularis interna in the neck region and at the level of the apertura thoracis cranialis, and the V. jugularis interna united with the V. thyroidea caudalis. In addition, on the right, the V. thyroidea cranialis joined the V. jugularis interna, at the level of the A. subclavia. The veins on both sides opened into the V. cava cranialis. Significant differences were observed between the sexes and detailed anatomical analysis of the glandula thyroidea and the glandula parathyroidea, and related vasculature and innervation, have been described in this paper.