The external jugular vein is a prominent superficial vein located in the neck that drains blood from the face, scalp, and superficial areas of the neck. It is formed by the union of the posterior auricular vein and the posterior division of the retromandibular vein near the angle of the mandible.
Location
The external jugular vein descends obliquely across the sternocleidomastoid muscle, running in the superficial fascia of the neck. It travels from the angle of the mandible toward the middle of the clavicle, ultimately draining into the subclavian vein near the base of the neck. Its superficial position makes it easily visible or palpable in certain individuals, especially when venous pressure is increased.
Structure and Anatomy
Formation and Origin
The external jugular vein is formed near the angle of the mandible by the union of two major veins:
- Posterior auricular vein: This vein drains blood from the scalp and the area behind the ear (auricle).
- Posterior division of the retromandibular vein: This vein drains the parotid gland and the lateral part of the face.
These two veins join just below the ear at the level of the angle of the mandible to form the external jugular vein.
Course and Pathway
The external jugular vein runs obliquely downward from its origin near the angle of the mandible across the lateral aspect of the neck. It descends superficially over the sternocleidomastoid muscle, running within the superficial fascia. Its course is generally straight, making it easily identifiable, especially in people with low body fat or increased venous pressure.
- The vein crosses the sternocleidomastoid muscle obliquely, heading toward the clavicle.
- As it approaches the base of the neck, the external jugular vein moves deeper, piercing the deep fascia of the neck (specifically the investing layer of deep cervical fascia) near the middle of the clavicle.
Termination
The external jugular vein terminates as it drains into the subclavian vein, which lies just above the clavicle and below the sternocleidomastoid muscle. This point is close to the venous angle, where the subclavian vein and internal jugular vein converge to form the brachiocephalic vein.
Tributaries
Along its course, the external jugular vein receives several smaller tributaries, which contribute to its drainage capacity:
- Transverse cervical vein: Drains the posterior and lateral regions of the neck and shoulders.
- Suprascapular vein: Drains the upper back and shoulder regions.
- Anterior jugular vein: In some cases, this vein may communicate with the external jugular vein, providing additional venous drainage from the anterior aspect of the neck.
- Occipital vein: May occasionally drain into the external jugular vein, especially in cases where it does not connect to the internal jugular vein.
Relations to Neighboring Structures
- Sternocleidomastoid Muscle: The external jugular vein runs superficially across the surface of this prominent muscle, making it easy to palpate or visualize under certain conditions.
- Superficial Cervical Fascia: The vein lies within this fascia, providing it with a superficial position in the neck.
- Investing Layer of Deep Cervical Fascia: Just before terminating, the external jugular vein pierces this layer, passing from a superficial position to a deeper one before draining into the subclavian vein.
- Clavicle: The external jugular vein runs adjacent to the clavicle as it approaches its termination in the subclavian vein.
Anatomical Variations
The anatomy of the external jugular vein can vary significantly between individuals. Some common variations include:
- Size and prominence: The size of the external jugular vein can differ, with some individuals having a more prominent and easily visible vein, while others have a smaller, less noticeable one.
- Termination point: While the external jugular vein typically drains into the subclavian vein, it may occasionally terminate at a slightly different point, either joining the internal jugular vein or the brachiocephalic vein directly.
- Additional tributaries: In some cases, the external jugular vein may receive additional tributaries from nearby regions, such as smaller veins from the anterior neck or scalp.
Anatomical Communications
The external jugular vein has several important communications with other venous structures, ensuring efficient drainage of blood from the head, neck, and shoulders:
- Internal Jugular Vein: Although it primarily drains into the subclavian vein, the external jugular vein may communicate with the internal jugular vein through small venous connections, providing alternative drainage pathways.
- Anterior Jugular Vein: There may be a communication between the external and anterior jugular veins, allowing for a redistribution of venous blood if needed.
- Venous Arch: Near the clavicle, the external jugular vein may be part of a venous arch that connects it with other veins, providing further redundancy in venous drainage. This arch is typically formed between the external jugular and anterior jugular veins.
Superficial Position and Surface Anatomy
Due to its superficial location, the external jugular vein is one of the few veins in the body that can be seen or palpated externally, particularly when venous pressure is increased. For example, during the Valsalva maneuver (forced exhalation against a closed airway), the external jugular vein may become distended, making it prominent on the surface of the neck. This visibility makes it a useful landmark in physical examinations, particularly for assessing venous pressure or diagnosing certain cardiovascular conditions.
Clinical Landmarks
The external jugular vein is often used as a landmark for various medical procedures or as a guide for venous access. It runs from the angle of the mandible to the middle of the clavicle, crossing the sternocleidomastoid muscle, and its position is important for catheterization and other venous procedures. Its visibility and straight course make it accessible for procedures such as intravenous cannulation, particularly in emergency or surgical settings.
Function
Venous Drainage of the Head and Neck
The primary function of the external jugular vein is to drain deoxygenated blood from the superficial areas of the head and neck. It receives blood from several key regions, including:
- Scalp: The external jugular vein collects blood from the posterior and lateral portions of the scalp, especially via the posterior auricular vein.
- Face: The posterior division of the retromandibular vein drains parts of the face, including the lateral cheek, and contributes to the formation of the external jugular vein.
- Auricular Region: The posterior auricular vein, which drains the area around and behind the ear (auricle), joins the retromandibular vein to form the external jugular vein. This allows for effective drainage from the lateral and posterior aspects of the head and ear.
The external jugular vein carries this venous blood downward from the head and neck toward larger venous structures, preventing the buildup of blood in the superficial tissues.
Connection to Central Circulation
The external jugular vein plays a crucial role in connecting the superficial venous drainage of the head and neck with the central venous system. After collecting blood from the scalp, face, and neck, the external jugular vein carries it to the subclavian vein, where it enters the larger veins of the thorax and is ultimately returned to the heart via the superior vena cava. This pathway is essential for ensuring the return of venous blood from the superficial areas of the head and neck to the central circulation.
Role in Venous Pressure Regulation
The external jugular vein can serve as an indicator of central venous pressure (CVP), which reflects the pressure in the right atrium of the heart. Because of its superficial location, the vein becomes distended when venous pressure increases. This distention is most noticeable when venous return to the heart is compromised, such as in conditions like heart failure or elevated intrathoracic pressure. The external jugular vein thus plays an important role in monitoring venous pressure and cardiac function, though indirectly. Clinicians often observe the external jugular vein to assess venous congestion or right-sided heart problems.
Collateral Circulation and Venous Redundancy
The external jugular vein contributes to collateral circulation in the neck, which ensures that venous blood can continue to flow, even if there are obstructions in other venous pathways. Through its connections with the anterior jugular vein, internal jugular vein, and other tributaries, the external jugular vein provides alternate routes for venous blood to drain from the head and neck. This collateral system is particularly important in conditions where venous flow is compromised, such as jugular vein thrombosis or when there is pressure on the venous system from tumors, inflammation, or trauma.
Drainage from the Neck and Shoulder Region
The external jugular vein also receives blood from the superficial regions of the neck and shoulder through tributaries such as the transverse cervical vein and the suprascapular vein. These veins drain the posterior and lateral neck, as well as portions of the upper back and shoulders. This ensures that superficial venous blood from these regions is efficiently returned to the central venous system, helping to prevent venous stasis or fluid buildup in the soft tissues of the neck and upper thorax.
Prevention of Venous Congestion
By providing a direct route for venous blood from the head and neck to flow into the subclavian vein, the external jugular vein helps prevent venous congestion in the superficial tissues. Without proper venous drainage, blood could accumulate in the soft tissues, leading to swelling (edema) and discomfort. The external jugular vein ensures that venous return is maintained, preventing conditions such as facial or neck edema, particularly in situations where venous pressure increases.
Thermoregulation
Like other superficial veins, the external jugular vein plays a minor role in thermoregulation by allowing heat exchange between the blood and the surrounding environment. Venous blood flowing through the external jugular vein can release excess heat from the scalp, face, and neck, helping to cool the body. This function is particularly relevant in maintaining temperature homeostasis during physical exertion or in hot environments, where the body’s need for heat dissipation is greater.
Role in Surgical and Medical Procedures
The external jugular vein is often used as a site for intravenous access in emergency situations or during medical procedures. Because of its superficial location and relatively straight course, it is accessible for cannulation, making it an ideal candidate for central venous access. This allows for the administration of medications, fluids, or blood products, as well as the measurement of central venous pressure in critically ill patients. Additionally, its position makes it a common target for procedures such as the insertion of central lines or other catheterization techniques.
Clinical Significance
The external jugular vein is clinically significant due to its superficial location and role in venous drainage of the head, neck, and shoulders. It is easily accessible for intravenous cannulation in emergency settings and can be used for central venous access, fluid administration, and pressure monitoring. Its prominence and visibility during increased venous pressure make it an important clinical marker for assessing central venous pressure (CVP), which can indicate conditions like heart failure or superior vena cava obstruction.
The external jugular vein is also prone to venous thrombosis, especially in cases of trauma or venous stasis, which can cause complications in venous drainage. Its superficial position makes it vulnerable to injury during neck surgeries, trauma, or invasive medical procedures. Understanding its anatomy and functions is essential for clinicians to avoid complications and ensure successful venous access during medical interventions.
