A rare arterial branch distributing to the thymus, ectopic intrathymic parathyroid, and thyroid glands which passed ventral to the right common carotid artery: a case report.

The intrathymic parathyroid has been reported that this variation might be related with the hyperthyroidism. In this study, the arterial pattern supplying the intrathymic parathyroid was examined in detail in the human cadaver (67-year-old, female, right side). The ectopic parathyroid was only detected on the right side, but not on the left side. This ectopic intrathymic parathyroid was supplied by the supernumerary arterial branch that originated from the inferior thyroid artery and passed ventral to the common carotid artery. This supernumerary branch further divided into two thin branches: (1) the one distributing the intrathymic parathyroid and the right lobe of the thyroid gland and (2) the other descending toward the thoracic cavity to supply the mediastinum organs. Other arteries supplying the thyroid gland and thymus of both sides were normal. In the surgical resection of the ectopic intrathymic parathyroid, physicians should pay attention to arteries ventral to the common carotid artery. This supernumerary branch distributing to the intrathymic parathyroid may be caused by incomplete division into the primordium for the inferior parathyroid and the primordium for the thymus on the developmental process.