Brachiocephalic artery

The brachiocephalic artery arises on a level with the upper border of the second right costal cartilage from the start of the aortic arch • anterior - left brachiocephalic vein and thymus • posterior - trachea • right - superior vena cava, right brachiocephalic vein, and pleura • left - left common carotid artery and thymus The thymus typically sits atop the brachiocephalic artery, and it separates the artery from the posterior surface of the manubrium of sternum. Branches The thyroid ima artery ascends in front of the trachea to the lower part of the thyroid, which it supplies. Variation The innominate artery usually gives off no branches, but occasionally a small branch, the thyroid ima artery, arises from it. Other times, it gives off a thymic or bronchial branch. Thyroid ima artery varies greatly in size, and appears to compensate for deficiency or absence of one of the other thyroid vessels. It occasionally arises from the aorta, the right common carotid, the subclavian or the internal mammary. == Development ==

The aortic sac is the embryological precursor of the proximal portion of the aortic arch. It is chronologically the first portion of the aorta to form, and appears as a dilation superior to the truncus arteriosus. Between the two horns of aortic sac, right horn gives rise to the brachiocephalic artery. Then the right horn fuses with the right-sided third and fourth aortic arches, which give rise to the right common carotid artery and the proximal right subclavian artery respectively. == Function ==

The brachiocephalic artery sends blood from the heart to the right arm, head, and neck. Oxygenated blood from the aortic trunk is taken through the brachiocephalic artery into the right subclavian artery, which transports blood to the right arm, and into the right common carotid artery, where blood is transported to the head and neck. == Clinical significance ==

Innominate artery aneurysms represent 3% of all arterial aneurysms. Because there is a risk of thromboembolic complications and spontaneous rupture, surgical repair is usually recommended early on after discovery. Innominate artery aneurysms often present with signs of innominate artery compression syndrome and have a very high risk of rupture. The majority of IA aneurysms are due to atherosclerosis. Other causes include syphilis, tuberculosis, Kawasaki's disease, Takayasu's arteritis, Behçet's disease, connective tissue disease, and angiosarcoma. Several abnormalities of the brachiocephalic artery have been reported. A retroesophageal innominate artery is a rare congenital anomaly. Also, aberrant innominate artery crossing anterior to the trachea just below the thyroid isthmus was reported. Anterior neck surgeries such as bronchoscopies and mediastinoscopies are common and safe procedure, since operating around the trachea, no major vessel is encountered in the surgical field. However, when this type of abnormality is encountered, even minor trauma can lead to mass bleeding culminating in death. Aberrant innominate artery can cause incomplete vascular ring. It does not completely encircle the trachea and esophagus, but some compress either the trachea or esophagus. Anomalous innominate artery originates later from the transverse arch and then crosses the trachea causing anterior tracheal compression. ==Additional images==

File:Slide15e.JPG|Brachiocephalic artery File:Slide3eeee.JPG|Brachiocephalic trunk == See also ==