External Jugular Veins

1. Overview

The external jugular veins are large veins located in the neck that play a vital role in returning deoxygenated blood from the head, face, and neck back to the heart. They are part of the venous system that drains blood from the upper body and direct it toward the right atrium of the heart for reoxygenation in the lungs. The external jugular veins are considered superficial veins, which means they are located near the surface of the skin and can be easily observed or palpated in certain clinical situations. They are formed by the confluence of the posterior auricular vein and the retromandibular vein, collecting blood from the face, scalp, and neck. The external jugular veins empty into the subclavian veins before ultimately draining into the superior vena cava.

2. Location

The external jugular veins are located on both sides of the neck, running from the head and face to the chest. They begin at the angle of the jaw, where they are formed by the union of two veins: the posterior auricular vein and the retromandibular vein. The external jugular veins travel down the neck, passing superficial to the sternocleidomastoid muscle, which helps in their identification during physical examination. They run laterally across the neck and eventually descend to the level of the clavicle (collarbone), where they empty into the subclavian veins. The external jugular veins are situated just beneath the skin, making them visible in some individuals, particularly when there is increased venous pressure or during conditions such as neck vein distention.

3. Structure

The external jugular veins are superficial veins that have a relatively simple structure compared to deeper veins in the body. Some key structural features of the external jugular veins include:

• Formation: The external jugular veins are formed by the confluence of the posterior auricular vein and the retromandibular vein. These veins drain blood from the scalp, face, and neck.

• Course: The external jugular veins run downward on either side of the neck, passing superficially over the sternocleidomastoid muscle. They descend towards the clavicle, where they empty into the subclavian veins.

• Diameter: The external jugular veins typically have a diameter of about 5 to 8 mm, depending on the individual and their health status. The veins are generally more prominent during certain physical activities or when venous pressure is elevated.

• Wall Composition: Like all veins, the external jugular veins are made up of three layers:

  • Intima: The innermost layer composed of endothelial cells that line the inside of the vein, providing a smooth surface for blood flow.

  • Media: The middle layer of smooth muscle and elastic tissue that allows the vein to expand and contract in response to changes in blood volume and pressure.

  • Adventitia: The outer layer made of connective tissue that provides structural support and anchors the vein to surrounding tissues.

• Valves: The external jugular veins contain one-way valves that prevent the backflow of blood, ensuring that blood moves in the direction of the heart. These valves are crucial in maintaining proper venous return and preventing blood from pooling in the lower parts of the veins.

4. Function

The primary function of the external jugular veins is to carry deoxygenated blood from the head, face, and neck back to the heart. Key functions of the external jugular veins include:

• Venous return from the head and neck: The external jugular veins collect deoxygenated blood from the head, face, and neck and transport it to the subclavian veins, which ultimately drain into the superior vena cava and return blood to the right atrium of the heart for oxygenation.

• Draining blood from the scalp and face: The external jugular veins drain blood from the superficial structures of the face, scalp, and neck, including the face muscles, skin, and superficial facial veins.

• Return of blood from the oral cavity and jaw: The external jugular veins also collect blood from the retromandibular vein, which drains the oral cavity, jaw, and parts of the head, ensuring that venous blood from these regions is efficiently returned to the heart.

• Support of venous return during physical activity: The external jugular veins, by providing a pathway for venous blood to return to the heart, help maintain circulatory efficiency, particularly during physical exertion or increased venous pressure (such as during intense exercise).

5. Physiological Role(s)

The external jugular veins play several critical physiological roles that contribute to maintaining healthy circulatory function in the head, neck, and upper body:

• Efficient venous return: The external jugular veins facilitate the return of blood from the head and neck back to the heart. This is crucial for maintaining circulatory efficiency and ensuring that blood is constantly replenished with oxygen in the lungs.

• Regulation of blood pressure: By helping to return blood to the heart, the external jugular veins play a role in maintaining blood pressure in the veins of the neck, face, and upper body. The venous pressure in these veins is typically low, but it is important for overall circulatory homeostasis.

• Support during exertion: During physical exertion, such as exercise, the body's demand for blood increases, particularly in the muscles of the neck and head. The external jugular veins help accommodate this demand by ensuring that blood from the upper body is efficiently returned to the heart.

• Pathway for venous blood from superficial structures: The external jugular veins provide a pathway for venous blood to drain from the skin, muscles, and superficial tissues of the face, scalp, and neck. This ensures that these structures do not become engorged with blood, allowing for efficient venous drainage.

6. Clinical Significance

The external jugular veins are clinically significant due to their role in venous return from the head, face, and neck. Abnormalities in the external jugular veins can be indicative of various clinical conditions. Some of the key clinical aspects of the external jugular veins include:

• Jugular venous distention (JVD): Jugular venous distention occurs when the external jugular veins become visibly enlarged or distended. This can be a sign of increased venous pressure or poor venous return to the heart, often associated with heart failure, right-sided heart failure, or fluid overload. JVD is commonly assessed during physical examinations to evaluate cardiovascular health.

• Central venous pressure measurement: The external jugular veins are sometimes used to measure central venous pressure (CVP), which provides an indication of the pressure in the right atrium of the heart. An elevated CVP can indicate conditions such as heart failure, dehydration, or fluid overload.

• External jugular vein thrombosis: Thrombosis (blood clot formation) in the external jugular veins is a rare but serious condition that can result in swelling, pain, and difficulty breathing if the clot becomes large or travels to the lungs. This can occur due to trauma, infection, or catheter placement. Treatment involves anticoagulation therapy and, in severe cases, thrombolysis or surgical removal of the clot.

• Carotid artery compression: Compression of the carotid artery or jugular veins can occur due to an abnormal position of the neck, tumors, or atherosclerosis. This can impede blood flow and lead to symptoms such as dizziness, lightheadedness, or fainting. Surgical or medical intervention may be required to relieve the compression.

• Venous insufficiency: Conditions like venous insufficiency can affect the external jugular veins, leading to blood pooling, swelling, or discomfort in the neck. This can occur due to poor vein valve function or blockage and is often seen in individuals with chronic venous disease or a history of blood clots. Treatment may include compression therapy, lifestyle changes, or surgical procedures.

The external jugular veins play a critical role in venous return from the upper body. Disorders such as jugular venous distention, thrombosis, or venous insufficiency can significantly impact cardiovascular health. Early diagnosis and management of these conditions are important for ensuring proper circulatory function and preventing complications.