Identify the anatomical structure indicated by the blue arrow in the image below.

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Options:
explanation: The image shows a dissection of the thoracic cavity. The pectoral muscles are laterally displaced on both sides. The sternum and the anterior chest wall (ribs and intercostal muscles) have also been removed. The lungs are visible as the spongy, grey structures, and the heart is present in the centre with the main vessels emerging. The left subclavian artery is the third branch of the aortic arch. However, the arrow indicates the first vessel emerging from the aortic arch – the brachiocephalic trunk, which subsequently bifurcates into the right common carotid artery and the right subclavian artery.
name: Left subclavian artery
label: b
answer: no
explanation: The image shows a dissection of the thoracic cavity. The pectoral muscles are laterally displaced on both sides. The sternum and the anterior chest wall (ribs and intercostal muscles) have also been removed. The lungs are visible as the spongy, grey structures, and the heart is present in the centre with the main vessels emerging. The arrow points to the first branch of the aortic arch – the brachiocephalic trunk, which subsequently bifurcates into the right common carotid artery and the right subclavian artery. The two other branches emerging from the aortic arch are the left common carotid artery and the left subclavian artery. The common carotids can be recognised as they ascend through the neck. Similarly, the subclavian vessels can be recognised as they travel towards the upper limbs.
name: Brachiocephalic trunk
label: a
answer: yes
explanation: The image shows a dissection of the thoracic cavity. The pectoral muscles are laterally displaced on both sides. The sternum and the anterior chest wall (ribs and intercostal muscles) have also been removed. The lungs are visible as the spongy, grey structures, and the heart is present in the centre with the main vessels emerging. The left common carotid artery is the second branch of the aortic arch. However, the arrow indicates the right-most vessel emerging from the aortic arch – the brachiocephalic trunk, which subsequently bifurcates into the right common carotid artery and the subclavian artery.
name: Left common carotid artery
label: c
answer: no
explanation: The image shows a dissection of the thoracic cavity. The pectoral muscles are laterally displaced on both sides. The sternum and the anterior chest wall (ribs and intercostal muscles) have also been removed. The lungs are visible as the spongy, grey structures, and the heart is present in the centre with the main vessels emerging. The arrow indicates the first branch emerging from the aortic arch – the brachiocephalic trunk. The brachiocephalic trunk in turn, bifurcates into the right common carotid artery and the right subclavian artery.
name: Right common carotid artery
label: e
answer: no
explanation: The image shows a dissection of the thoracic cavity. The pectoral muscles are laterally displaced on both sides. The sternum and the anterior chest wall (ribs and intercostal muscles) have also been removed. The lungs are visible as the spongy, grey structures, and the heart is present in the centre with the main vessels emerging. The arrow indicates the first branch of the aortic arch, the brachiocephalic trunk. The brachiocephalic trunk subsequently bifurcates into the right common carotid artery and the right subclavian artery.
name: Right subclavian artery
label: d
answer: no

Correct answer: a