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 * Epidural venous plexus * External vertebral venous plexuses * Internal ve ...

on the

thyroid gland The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is a butterfly-shaped gland located in the neck below the Adam's apple. It consists of two connected lobes. The lower two thirds of the lobes are connected by ...

, communicating with the

middle Middle or The Middle may refer to: * Centre (geometry), the point equally distant from the outer limits. Places * Middle (sheading), a subdivision of the Isle of Man * Middle Bay (disambiguation) * Middle Brook (disambiguation) * Middle Creek ...

and

superior thyroid vein The superior thyroid vein is the vena comitans of the superior thyroid artery. It is formed by the union of deep and superficial tributaries that correspond to the arterial branches of the superior thyroid artery. Its tributaries are the . The v ...

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 posteri ...

, the inferior thyroid veins drain directly to the brachiocephalic veins. The inferior thyroid veins form a

plexus In anatomy, a plexus (from the Latin term for 'braid') is a branching network of blood vessels, lymphatic vessels, or nerves. The nerves are typically axons outside the central nervous system. The standard plural form in English is plexuses. Al ...

in front of the

trachea The trachea (: tracheae or tracheas), 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 animals' lungs. The trachea extends from ...

, behind the

sternothyroid muscle The sternothyroid muscle (or sternothyroideus) is an infrahyoid muscle of the neck. It acts to depress the hyoid bone. Structure The two muscles are in contact with each other proximally (close to their origin), but diverge distally (towards t ...

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

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 vei ...

; sometimes the right and left veins open by a common trunk in the latter situation. Occasionally, a fourth thyroid vein—known as Kocher’s vein—may be present, arising between the middle and inferior thyroid veins and draining into the internal jugular vein. The inferior thyroid veins receive esophageal, tracheal, and inferior laryngeal veins, and are provided with valves at their terminations in the brachiocephalic veins.

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