Brachiocephalic vein (Innominate vein)
The brachiocephalic vein, also known as the innominate vein, is a paired vein of the superior mediastinum that drains the venous blood from the head and neck, upper limbs and the upper part of the thorax. It is formed by the confluence of the internal jugular and subclavian veins on each side, just posterior to the sternoclavicular joint.
The left and right brachiocephalic vein course towards the midline and unite at the level of the inferior border of the 1st right costal cartilage to form the superior vena cava.
|Drains from||Confluence of subclavian and internal jugular veins|
|Tributaries||Inferior thyroid veins, posterior intercostal veins of the 1st intercostal space, thymic veins, Internal thoracic veins|
|Drains to||Superior vena cava|
|Drainage area||Head, neck, upper limb, upper thorax|
This article will discuss the anatomy and function of the brachiocephalic vein.
Origin and course
The left and right brachiocephalic veins begin posteriorly to the respective left and right sternoclavicular joints, arising from the union of the internal jugular and subclavian veins. This union is commonly referred to as the venous angle, in which the thoracic duct on the left, and right lymphatic trunk on the right side drain the lymph into the venous circulation. Thus, the brachiocephalic vein is deemed as the site of convergence of the venous and lymphatic systems.
The left brachiocephalic vein courses obliquely downwards and medially, measuring approximately 6 to 8 centimeters in length. On its course, the left brachiocephalic vein is related posteriorly to the trachea, left phrenic and left vagus nerves, left internal thoracic artery and the three major branches of the arch of the aorta; the brachiocephalic trunk, common carotid and the left subclavian artery. Anteriorly, the left brachiocephalic vein is in contact, and partially embedded in the thymus gland, and separated from the sternoclavicular joint by the sternohyoid and sternothyroid muscles. The left brachiocephalic vein initially courses adjacent to the medial surface of the apex of the left lung and is overlapped by the right pleura near its termination.
The right brachiocephalic vein has a shorter and a more vertical course, being approximately 2 centimeters long. It runs anterolateral to the brachiocephalic trunk and right vagus nerve. In its initial course, the right brachiocephalic vein is found anterior to the right pleura, phrenic nerve and internal thoracic artery, while later in its course it turns to their medial side.
At the level of the inferior border of the 1st right costal cartilage, the left and right brachiocephalic veins converge to form the superior vena cava, which goes on to drain into the right atrium of the heart.
Tributaries and drainage area
The left and right brachiocephalic veins receive different tributaries. Via these tributaries, the brachiocephalic veins receive venous blood from the head, neck, upper limb, and the upper part of the thorax.
Left brachiocephalic vein
The tributaries of the left brachiocephalic vein are the left vertebral, internal thoracic, inferior thyroid and superior intercostal veins. In addition, it often receives the thymic, supreme intercostal, pericardiacophrenic and the left posterior intercostal vein of the 1st intercostal space.
Right brachiocephalic vein
The tributaries of the right brachiocephalic vein are the right vertebral, internal thoracic and inferior thyroid veins, and occasionally the right posterior intercostal vein of the 1st intercostal space.