At its origin, it is somewhat dilated, and this dilatation is called the superior bulb.
It also has a common trunk into which drains the anterior branch of the retro mandibular 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, 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 dilatation, 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 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 are placed about 2.5 cm above the termination of the vessel.
The JVP can also be artificially raised by applying pressure to the liver (the hepatojugular reflux). This method is used to locate the JVP and distinguish it from the carotid pulse. Unlike the carotid pulse, the JVP is impalpable.
Because the internal jugular rarely varies in its location, it is easier to find than other veins. However, sometimes when a line is inserted the jugular is missed and other structures such as the carotid artery or the vagus nerve (CN X) are punctured, causing damage to those structures.