The brachial veins are paired deep veins that accompany the brachial artery in the upper arm. These veins are responsible for draining deoxygenated blood from the muscles and tissues of the upper arm. They typically run parallel to the brachial artery, starting near the elbow, where the radial and ulnar veins converge, and extending up the arm toward the shoulder. The brachial veins travel deep within the arm’s musculature, beneath the biceps brachii and adjacent to the humerus bone. These veins terminate as they merge with the basilic vein to form the axillary vein near the armpit (axilla).
Structure and Anatomy
Location
The brachial veins are deep veins located in the upper arm, running alongside the brachial artery. They extend from the elbow to the shoulder, where they join the basilic vein to form the axillary vein. These veins are part of the deep venous system and are located deep beneath the muscles and fascia of the arm, primarily draining the structures of the upper arm.
Origin
The brachial veins originate at the elbow from the confluence of the radial and ulnar veins. These veins merge in the cubital fossa (the anterior region of the elbow), forming two brachial veins that travel upward alongside the brachial artery. The origin of the brachial veins marks the point where the deep venous drainage from the forearm converges to continue the journey toward the heart.
Course
The brachial veins run parallel to the brachial artery along the length of the upper arm. Typically, two veins, referred to as venae comitantes, accompany the artery, one on either side, with small anastomotic branches connecting them at intervals. These veins remain close to the humerus, traveling deep within the arm, beneath muscles such as the biceps brachii and brachialis. As they ascend, they move through the medial aspect of the upper arm toward the shoulder.
Relations
- Superficial (anterior) relations: The brachial veins are deep to the biceps brachii muscle, which covers them for much of their course along the upper arm. They are also located beneath the skin and subcutaneous tissue.
- Deep (posterior) relations: The veins lie close to the humerus bone along their entire length and are also in proximity to the brachialis muscle, which runs along the anterior surface of the humerus.
- Medial relations: Medially, the veins run close to the median nerve, which travels in close association with the brachial artery and the veins. This close proximity is important in the context of surgical procedures or trauma to the arm.
- Lateral relations: Lateral to the veins is the lateral aspect of the humerus and the musculature of the arm, including parts of the triceps and brachialis.
Tributaries
Along their course, the brachial veins receive blood from various tributaries that drain different parts of the upper arm. These tributaries include:
- Deep venous branches from the muscles of the upper arm, including the biceps brachii, brachialis, and triceps muscles.
- Venous drainage from the humerus, collecting blood from the bone itself through smaller venous branches.
- Perforating veins that connect the brachial veins to the superficial veins of the arm, helping maintain venous return balance between the deep and superficial venous systems.
- Venous tributaries from the deep structures of the elbow joint, which also contribute to the venous return toward the brachial veins.
Termination
The brachial veins terminate as they merge with the basilic vein near the inferior border of the teres major muscle, just before entering the axilla (armpit). This junction forms the axillary vein, which continues to transport blood from the upper limb toward the central venous system. The axillary vein eventually drains into the subclavian vein, a major vessel that returns blood to the heart.
Surrounding Structures
- Anteriorly: The brachial veins are covered by the biceps brachii and subcutaneous tissues as they travel up the arm.
- Posteriorly: The veins are related to the humerus and the brachialis muscle, which lies deep within the arm.
- Medially: The median nerve runs along the medial side of the brachial veins and artery, closely associated with them.
- Lateral relations: The musculature of the upper arm, including portions of the triceps, runs laterally to the brachial veins.
Function
Venous Return from the Upper Arm
The primary function of the brachial veins is to drain deoxygenated blood from the structures of the upper arm, including muscles, bones, and connective tissues. The brachial veins receive blood from deep structures such as the biceps brachii, brachialis, and triceps muscles, transporting it back toward the heart. They play a vital role in maintaining proper circulation in the upper limb, preventing blood pooling and ensuring a continuous flow toward central venous circulation.
Drainage of the Elbow Region
The brachial veins also collect blood from the deep venous structures surrounding the elbow joint. This includes tributaries from the radial and ulnar veins, which drain the forearm and hand, as well as smaller venous branches from the elbow joint itself. The efficient drainage of the elbow region is essential for maintaining joint health and preventing conditions such as venous congestion, which could result in swelling or discomfort in the elbow.
Connection with Forearm Venous System
The brachial veins serve as a crucial link between the forearm’s deep venous system and the upper limb’s central venous system. By receiving blood from the radial and ulnar veins at the level of the elbow, the brachial veins ensure that deoxygenated blood from the forearm and hand is efficiently returned to the heart. This connection prevents the accumulation of blood in the lower portions of the arm and promotes healthy circulation throughout the upper limb.
Contribution to the Formation of the Axillary Vein
As the brachial veins ascend toward the shoulder, they merge with the basilic vein to form the axillary vein. This transition marks the point where the deep venous return from the upper arm is integrated into the larger venous system responsible for returning blood from the entire upper limb to the heart. The axillary vein then drains into the subclavian vein, which is part of the central venous system. The brachial veins, therefore, play a key role in ensuring the continuity of venous return from the upper limb to the heart.
Venous Drainage from the Humerus
The brachial veins are responsible for draining blood from the humerus, the long bone of the upper arm. The bone is vascularized by small venous branches that connect to the brachial veins. These veins help remove deoxygenated blood from the bone tissue, ensuring proper metabolic exchange and preventing the buildup of waste products. This function is essential for bone health, as it allows for the regular circulation of nutrients and removal of cellular by-products.
Regulation of Venous Pressure in the Upper Arm
The brachial veins, in conjunction with the surrounding muscles, help regulate venous pressure within the upper arm. During muscle contraction, particularly in activities such as lifting or arm movement, the surrounding muscles compress the veins, aiding venous return to the heart. This muscle-venous interaction, known as the muscle pump mechanism, enhances venous return, reduces the risk of blood pooling, and ensures efficient circulation throughout the upper arm. This mechanism is especially important during physical activity when increased circulation is necessary to support muscle function.
Communication with Superficial Venous System
While the brachial veins are part of the deep venous system, they communicate with the superficial veins, such as the cephalic and basilic veins, via perforating veins. These perforating veins help balance venous pressure between the deep and superficial systems, ensuring that blood flow is efficiently distributed and that no area of the arm experiences excessive venous pressure. This communication allows for flexibility in venous drainage and helps prevent complications such as varicose veins or venous congestion.
Thermoregulation
Although the brachial veins are not primarily involved in thermoregulation, they indirectly participate in this process. In cold conditions, the body conserves heat by diverting blood away from the skin’s surface and toward deeper veins like the brachial veins. This helps retain body heat by minimizing heat loss through the skin. Conversely, in warm conditions, blood is directed more toward the superficial veins to facilitate heat dissipation. This dynamic adjustment contributes to maintaining the body’s internal temperature within a safe range.
Role in Muscle Pump Action
The brachial veins benefit from the muscle pump action in the upper arm, which aids in venous return. During physical activity, the contraction of muscles surrounding the veins, such as the biceps brachii and triceps, compresses the veins and helps push blood upward against gravity. This is particularly important for maintaining venous return during activities like exercise, where increased circulation is necessary to meet the body’s metabolic demands. The muscle pump action prevents venous stasis, reduces the likelihood of venous pooling, and ensures efficient circulation throughout the upper arm.
Clinical Significance
The brachial veins play an essential role in both clinical procedures and pathological conditions. They are often involved in conditions such as deep vein thrombosis (DVT), particularly in the upper limb, which can occur following trauma, surgery, or prolonged immobilization. DVT in the brachial veins can cause swelling, pain, and impaired blood flow in the arm, and may pose a risk for pulmonary embolism if clots travel to the lungs.
Additionally, the brachial veins are significant in venous access for intravenous therapies, particularly in cases where superficial veins are unavailable or compromised. Surgeons may also utilize the brachial veins when creating arteriovenous fistulas for dialysis in patients with renal failure.
The proximity to the brachial artery and median nerve means any vascular injury or complication involving the brachial veins, such as trauma or thrombosis, could affect surrounding structures, leading to complications like nerve compression or arterial injury.
