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10 reported a similar case in which the brachiocephalic and left common carotid arteries arose from a common trunk. 9 In a Kenyan population in Africa, the incidence of this variation was found to be 25.7% of the 113 aortic arches of adult cadavers. During routine dissection in the previous academic year we came across and documented a similar variation in the branching pattern of the aortic arch except that the left common carotid artery arose from the brachiocephalic artery. The most common variation in branching pattern of the aortic arch occurs when the branches are reduced to two 1, 3 as in our case report in which the brachiocephalic and left common carotid arteries arose from a common trunk on the aortic arch ( Figure 1). Embryological malformations especially of the fourth aortic arch in the first 12weeks of foetal life results in variations in the branching pattern of the aortic arch and these abnormalities may be asymptomatic whilst some symptomatic when vascular rings surround the trachea and oesophagus causing obstruction. 1, 2, 4, 7Standring 1 reports of rare variations such as external and internal carotid arteries arising separately, the common carotid being absent on one or both sides, or both carotids and one or both vertebral arteries may be separate branches. Variations in the branching pattern of the aortic arch may include origin of the left common carotid artery from the brachiocephalic trunk, common trunk origin of the brachiocephalic and left common carotid arteries, origin of left common carotid and subclavian arteries may arise from a left brachiocephalic trunk, origin of left vertebral artery between the left common carotid and the subclavian arteries. This is the most common pattern occurring in about 65-75% of the population.

1 The arch of the aorta normally gives rise to three branches namely the brachiocephalic, left common carotid and left subclavian arteries. The arch of the aorta lies in the superior mediastinum and extends from the level of the second right sternocostal joint and ascends diagonally and to the left anterior to the trachea and descends to the left of the fourth thoracic vertebral body continuing as the descending thoracic aorta.