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 posterior compartment of the jugular foramen, at the base of the skull. It is somewhat dilated at its origin, which is called the superior bulb.

This vein also has a common trunk into which drains the anterior branch of the retromandibular vein, the facial vein, and the lingual vein.

It runs down the side of the neck in a vertical direction, being at one end lateral to the internal carotid artery, and then lateral to the common carotid artery, and at the root of the neck, it unites with the subclavian vein to form the brachiocephalic vein (innominate vein); a little above its termination is a second dilation, the inferior bulb.

Above, it lies upon the rectus capitis lateralis, behind the internal carotid artery and the nerves passing through the jugular foramen. Lower down, the vein and artery lie upon the same plane, the glossopharyngeal and hypoglossal nerves passing forward between them. The vagus nerve descends between and behind the vein and the artery in the same sheath (the carotid sheath), and the accessory runs obliquely backward, superficial or deep to the vein.

At the root of the neck, the right internal jugular vein is a little distance from the common carotid artery, and crosses the first part of the subclavian artery, while the left internal jugular vein usually overlaps the common carotid artery.

The left vein is generally smaller than the right, and each contains a pair of valves, which exist about 2.5 cm above the termination of the vessel.

In 9–12% of the Western population, the size, shape or course of the internal jugular vein is abnormal. Variants identified including veins markedly smaller, or not functionally present. The mean diameter is 10 mm, but may range between 5 and 35 mm.