An anatomical study of the thyroid arteries anastomoses.

Collateral circles in neck own a particular importance in compensating the symptoms due to the unilateral occlusion of the common carotid artery. In addition, surgical procedures at the level of the thyroid gland and larynx raise the problem of a good knowledge of the arterial morphology at those levels. The present study was designed to investigate the possible morphologies of the thyroid arteries anastomoses. For the present study, 20 human adult specimens were dissected, 15 in cadavers and other five on laryngeal specimens drawn at autopsies. Dissections evidenced bilateral and unilateral anastomoses of the thyroid arteries classified as extra laryngeal and intra laryngeal, the former constantly being represented by the supra isthmic arcade made by the superior thyroid arteries and the retrolobar anastomoses of the superior and inferior thyroid arteries. Constant intra laryngeal anastomoses were those of the superior laryngeal artery with the inferior laryngeal artery and, respectively, with the cricothyroid artery. The analogy with the cardiac collateral circulation, the thyroid arteries anastomoses may be classified as intrathyroid and interthyroid arterial anastomoses. We also present in this paper a rare variant that we did not find described in the references we investigated, represented by the paramedian perilaryngeal anastomose of the suprahyoid branch emerged from the lingual artery and the cricothyroid artery sent by the superior thyroid artery. The thyroid arteries supply the collateral circles in neck; the clinicians must be aware of their possible functional value and the surgeons must take into account these arterial morphologies while acting on the neck viscera.