The jugular veins are major blood vessels located in the neck, responsible for returning deoxygenated blood from the brain, head, and face back toward the heart. This function is fundamental to the circulatory system, especially considering the brain’s high demand for oxygenated blood. The jugular veins ensure the efficient return of used blood to the chest for re-oxygenation, serving as the main drainage system for the entire head region.
The Two Primary Jugular Vein Systems
The venous drainage of the head and neck is handled primarily by two distinct pairs of vessels: the Internal Jugular Vein (IJV) and the External Jugular Vein (EJV). They differ significantly in their anatomical depth and the specific areas they drain.
The IJV is a larger, deeper vessel that collects blood mainly from the internal structures of the skull, including the brain. It begins at the base of the skull and descends through the neck, remaining hidden beneath muscle and fascia. In contrast, the EJV is smaller and superficial, draining blood from structures outside the cranium, such as the scalp and parts of the face.
Anatomical Placement of the Internal Jugular Vein
The Internal Jugular Vein (IJV) follows a deep path down the side of the neck. It originates inside the skull as a continuation of the sigmoid sinus and exits through the jugular foramen at the base of the skull. From there, it descends within a protective structure known as the carotid sheath.
The carotid sheath is deep cervical fascia that also encases the common carotid artery and the vagus nerve. Within this sheath, the IJV runs parallel and lateral to the common carotid artery. The vein travels deep to the Sternocleidomastoid muscle (SCM) for most of its course.
At the base of the neck, the IJV is located in the triangular space formed by the two lower attachments of the SCM. This location is used by medical professionals to gain access to the vein. The IJV eventually joins with the subclavian vein, which runs beneath the collarbone, to form the brachiocephalic vein.
Anatomical Placement of the External Jugular Vein
The External Jugular Vein (EJV) is closer to the skin’s surface, making it easily identifiable. It begins just below the ear, near the angle of the jaw, formed by the union of two other veins. From its origin, the EJV takes a diagonal path downward across the neck.
The vein runs obliquely over the surface of the Sternocleidomastoid muscle. Because of its superficial position, running just beneath the skin and the platysma muscle, the EJV often becomes visible when a person strains or holds their breath. It continues toward the collarbone (clavicle), where it penetrates the deep fascia of the neck. The EJV terminates by draining into the subclavian vein, deep to the clavicle.
Clinical Importance of Jugular Location
The location of the jugular veins holds diagnostic and therapeutic importance in medicine. The Internal Jugular Vein (IJV) is used to monitor Jugular Venous Pressure (JVP), which is an indirect estimate of the pressure within the right atrium of the heart. Since the IJV connects directly to the heart via the superior vena cava, changes in heart function or fluid balance are reflected in the height of the blood column visible in the vein. An elevated JVP can indicate conditions like heart failure or fluid overload, providing a non-invasive tool for cardiovascular assessment.
The deep location of the IJV also makes it a primary site for establishing Central Venous Access (CVA). This procedure involves inserting a catheter into the vein to reach the large veins near the heart. CVA is necessary for administering medications, fluids, or nutrition, and for monitoring central blood pressure. Knowledge of the IJV’s relationship to the carotid artery and the Sternocleidomastoid muscle allows medical personnel to safely cannulate the vessel. The superficial External Jugular Vein can also be used for rapid venous access when peripheral veins are difficult to find, serving as a quick route for fluid administration in emergencies.