Abnormal Origin of Right Subclavian Artery-Embryological Basis and Clinical Significance

Abstract

BACKGROUND Variations in the branching of the human aortic arch have clinical significance. An Aberrant Right Subclavian Artery (ARSA) arises as the last branch of the left-sided aortic arch distal to the normally-positioned left subclavian artery. ARSA usually remains asymptomatic and is revealed incidentally either radiologically or during anatomy dissection. It is associated with several congenital cardiovascular anomalies and some chromosomal syndromes. MATERIALS AND METHODS Fifty cadavers were dissected and observed for aortic arch branching pattern variations during routine undergraduate dissection over a period of two years in Institute of Anatomy, Madurai Medical College, Madurai, Tamilnadu. RESULTS One case of aberrant right subclavian artery was noted. The right subclavian artery arose from the right lateral surface of proximal part of descending aorta distal to ligamentum arteriosum. It was seen to course upwards, obliquely towards the right, passing posterior to trachea and oesophagus. The right recurrent laryngeal nerve on arising from the right vagus ran transversely towards inferior pole of the right lateral lobe of thyroid gland and entered the larynx behind the cricothyroid joint. The course of right laryngeal nerve was short and non-recurrent. CONCLUSION Awareness of this anatomical variation will provide useful knowledge to anatomists, radiologists, cardiologists, vascular and thoracic surgeons and thereby prevent injury to aberrant right subclavian artery and right recurrent laryngeal nerve during radiological and surgical interventions.