The inferior thyroid veins appear two, frequently three or four, in number, and arise in the

venous plexus In vertebrates, a venous plexus is a normal congregation anywhere in the body of multiple veins. A list of venous plexuses: * Basilar plexus * Batson venous plexus * Internal vertebral venous plexuses * Pterygoid plexus * Submucosal venous ...

on the thyroid gland, communicating with the middle and

superior thyroid vein The superior thyroid vein begins in the substance and on the surface of the thyroid gland, by tributaries corresponding with the branches of the superior thyroid artery, and ends in the upper part of the internal jugular vein. It receives the sup ...

s. While the superior and middle thyroid veins serve as direct tributaries to the

internal jugular vein The internal jugular vein is a paired jugular vein that collects blood from the brain and the superficial parts of the face and neck. This vein runs in the carotid sheath with the common carotid artery and vagus nerve. It begins in the poste ...

, the inferior thyroid veins drain directly to the

brachiocephalic veins The left and right brachiocephalic veins (previously called innominate veins) are major veins in the upper chest, formed by the union of each corresponding internal jugular vein and subclavian vein. This is at the level of the sternoclavicular j ...

. The inferior thyroid veins form a

plexus In neuroanatomy, a plexus (from the Latin term for "braid") is a branching network of vessels or nerves. The vessels may be blood vessels (veins, capillaries) or lymphatic vessels. The nerves are typically axons outside the central nervous syste ...

in front of the

trachea The trachea, also known as the windpipe, is a cartilaginous tube that connects the larynx to the bronchi of the lungs, allowing the passage of air, and so is present in almost all air- breathing animals with lungs. The trachea extends from the ...

, behind the

sternothyroid muscle The sternothyroid muscle, or sternothyroideus, is an infrahyoid muscle in the neck. It acts to depress the hyoid bone. It is below the sternohyoid muscle. It is shorter and wider than the sternohyoid. Structure The sternothyroid arises from the ...

. From this plexus, the left vein descends and joins the left brachiocephalic vein, and the right vein passes obliquely downward and to the right across the

brachiocephalic artery The brachiocephalic artery (or brachiocephalic trunk or innominate artery) is an artery of the mediastinum that supplies blood to the right arm and the head and neck. It is the first branch of the aortic arch. Soon after it emerges, the brachioce ...

to open into the right brachiocephalic vein, just at its junction with the

superior vena cava The superior vena cava (SVC) is the superior of the two venae cavae, the great venous trunks that return deoxygenated blood from the systemic circulation to the right atrium of the heart. It is a large-diameter (24 mm) short length vein th ...

; sometimes the right and left veins open by a common trunk in the latter situation. The inferior thyroid veins receive esophageal, tracheal, and inferior laryngeal veins, and are provided with valves at their terminations in the

Additional images

File:Gray505.png, The arch of the aorta, and its branches. File:Gray562.png, The fascia and middle thyroid veins. File:Gray1178.png, The thymus of a full-term fetus, exposed in situ. File:Head ap anatomy.jpg, Head anatomy anterior view

References

Veins of the head and neck Thyroid {{circulatory-stub