The internal jugular vein is a major blood vessel that drains blood from important body organs and parts, such as the brain, face, and neck.

Anatomically, there are two of these veins that lie along each side of the neck. They each rest beside the thyroid gland at the center of the neck, just above the collarbone and near the trachea, or windpipe. These veins functions to carry oxygen-depleted blood from the brain, face, and neck, and transport it to the heart through the superior vena cava.

Generally, the left vein is somewhat smaller and thinner than the right, but both contain valves that assist with blood transport. The vein appears dilated (wider) at two points, and these distinct parts are called the superior bulb and the inferior bulb.

The vein plays an important role in assessing jugular vein pressure, especially among people with heart disorders. Measurements of jugular vein pressure are used to evaluate central venous pressure, which indicates how much blood is returning to the heart and how well the heart is pumping blood back into the arteries. Because this vein is also larger than most others, it is commonly used as an entry point to place venous lines, which are tubes (catheters) that are used to carry medicine or nutrients into the body.

Because of its superficial location (near the outside of the body), the internal jugular vein is quite susceptible to injury, trauma, or damage. It also lacks protection from strong structures, like bones or cartilages. When blood flow to the vein is impeded or affected, shock or death will ultimately occur.