The jugular veins are major blood vessels present on both the left and right sides of the neck. They are a system of vessels responsible for collecting deoxygenated blood from the entire head, including the brain and face, and returning it toward the heart. This venous network is made up of three main pairs—the internal, external, and anterior jugular veins. Their collective function is continuous, low-pressure drainage necessary for maintaining proper circulation within the head.
The Internal and External Jugular Veins
The jugular system is broadly divided into the internal and external jugular veins, which differ significantly in size and the structures they drain. The Internal Jugular Vein (IJV) is the largest of the neck veins, originating at the base of the skull as a continuation of the sigmoid sinus. It drains blood primarily from the brain, the deep parts of the face, and the neck structures. The IJV runs deep within the neck alongside the common carotid artery and the vagus nerve, enclosed in the protective carotid sheath.
The External Jugular Vein (EJV) is a more superficial vessel that runs closer to the skin’s surface. It forms from the combination of veins that drain the scalp and the external areas of the face. The EJV is smaller than the IJV and runs down the side of the neck before emptying into the subclavian vein near the collarbone. The anterior jugular veins are a third, smaller pair that run down the front midline of the neck and are subject to greater anatomical variation.
Visualizing Their Location on the Neck
The distinct locations of the jugular veins determine their visibility and accessibility on the neck. The External Jugular Vein is often visible beneath the skin, tracing a diagonal line across the sternocleidomastoid muscle. This visibility increases when a person strains, sings, or lies flat, as the rise in venous pressure causes the vein to temporarily distend.
In contrast, the Internal Jugular Vein remains deep and is not visible or palpable by the average person, providing it with protection. It descends behind the sternocleidomastoid muscle, safely positioned within the carotid sheath near the pulse point of the carotid artery. This protected, deep path makes the IJV a less likely target for surface injury than the more exposed EJV.
The Role of Jugular Veins
The function of the jugular veins is to ensure the continuous return of blood to the heart. Both the internal and external jugular veins merge with the subclavian veins near the base of the neck, forming the brachiocephalic veins. These then join to create the superior vena cava, which delivers the deoxygenated blood directly to the right atrium of the heart. This pathway maintains the low-pressure environment necessary for blood to flow out of the cranium and prevent pressure buildup in the brain.
Physicians utilize the internal jugular vein for its direct connection to the right side of the heart, using it to estimate central venous pressure (CVP). By observing the height of the jugular venous pulse, doctors gain insight into a patient’s overall fluid status and the function of the right ventricle. An elevated CVP, indicated by a distended jugular vein, can be a sign of conditions like heart failure or fluid overload.