The brachiocephalic trunk is a short and thick artery which supplies the head, right shoulder, and right arm. It originates from the first portion of arch of aorta. Then it runs upwards, obliquely to the right, to divide at the level of the right sternoclavicular joint into two important branches; the right common carotid artery, which supplies the head, and the right subclavian artery, which supplies the right shoulder and arm with oxygenated blood.
The brachiocephalic trunk is also known as the innominate artery, which is 4 cm in length. In some individual, it also gives off the thyroidea ima artery, which supplies the inferior part of thyroid gland and trachea. Also the following developmental variants are rarely encountered: 1) the brachiocephalic trunk is absent, with the right common carotid and the right subclavian artery arising straight from the arch of aorta; 2) the innominate artery originates from the left side instead of the right; 3) a least frequent occurrence when there are two brachiocephalic trunks instead of one.
Below, you can see a schematic image of heart and arch of aorta, showing the innominate artery (brachiocephalic trunk).
