Brachial artery

The brachial artery is the main artery of the upper arm, supplying oxygenated blood to the arm’s muscles, bones, and other tissues. It is a continuation of the axillary artery and is a key vessel in the arterial system of the upper limb. The brachial artery is often used for measuring blood pressure using a sphygmomanometer because of its superficial location in the arm. It is also commonly accessed for arterial blood sampling or for arterial cannulation in medical procedures.

Location

The brachial artery begins at the lower border of the teres major muscle, as a continuation of the axillary artery. It runs down the anterior aspect of the arm, traveling along the medial side of the biceps brachii muscle. The artery passes through the cubital fossa at the elbow, where it bifurcates into the radial and ulnar arteries. Throughout its course, the brachial artery is relatively superficial, lying just beneath the skin and fascia, making it easily palpable, especially in the cubital fossa region.

Anatomy

The brachial artery is the primary artery that supplies the upper arm, and its anatomy plays a crucial role in the vascular system of the upper limb. Below is a detailed description of its origin, course, branches, and relationship to surrounding structures.

Origin

The brachial artery is a direct continuation of the axillary artery, which transitions into the brachial artery as it passes the lower border of the teres major muscle. The axillary artery supplies the shoulder and upper thoracic regions, while the brachial artery takes over as the main vessel responsible for delivering blood to the arm.

Course

The brachial artery travels along the anterior aspect of the arm, following a relatively superficial course, making it easily accessible for medical examinations and procedures. The artery passes along the medial side of the arm and is accompanied by the median nerve for much of its length.

Proximal Arm

In the upper part of the arm, the brachial artery runs along the medial border of the biceps brachii muscle and is located deep to the bicipital aponeurosis. Initially, it is somewhat protected by surrounding muscles and fascia, but as it continues downward, it becomes more superficial.

Relationship to Muscles: In this region, the artery is positioned medial to the biceps brachii muscle and lies adjacent to the coracobrachialis and brachialis muscles. The artery is accompanied by the median nerve, which crosses anteriorly from lateral to medial around the artery as it descends toward the elbow.

Distal Arm

As the brachial artery approaches the elbow, it moves more superficially. The artery runs anterior to the brachialis muscle and deep to the bicipital aponeurosis, which protects it as it enters the cubital fossa, a triangular depression located anterior to the elbow joint.

Cubital Fossa: The cubital fossa is an important anatomical area where the brachial artery can be palpated and accessed for procedures. Here, the artery lies lateral to the median nerve and medial to the biceps tendon. The radial nerve lies more laterally and slightly deeper.

Branches

The brachial artery gives rise to several important branches along its course, supplying blood to various muscles and structures of the arm. These branches also contribute to the collateral circulation around the elbow.

Profunda Brachii Artery (Deep Artery of the Arm)

One of the first and largest branches of the brachial artery is the profunda brachii artery, also known as the deep artery of the arm. This artery arises near the upper part of the arm and travels posteriorly with the radial nerve through the radial groove of the humerus. It supplies blood to the posterior compartment of the arm, particularly the triceps brachii muscle, and contributes to the collateral circulation around the elbow.

Superior Ulnar Collateral Artery

The superior ulnar collateral artery arises from the medial aspect of the brachial artery, typically in the mid-arm. It travels alongside the ulnar nerve and descends toward the elbow, where it contributes to the collateral circulation around the medial epicondyle of the humerus, anastomosing with branches of the ulnar artery.

Inferior Ulnar Collateral Artery

This branch arises just above the elbow and runs medially toward the joint, forming an anastomosis with other arteries in the region to supply blood to the elbow joint and surrounding tissues.

Nutrient Artery

The brachial artery also gives off small nutrient arteries that supply blood to the humerus itself, nourishing the bone.

Terminal Branches

As the brachial artery descends through the cubital fossa, it reaches its termination by bifurcating into its two main terminal branches:

• Radial Artery: The radial artery runs along the lateral aspect of the forearm and supplies blood to the lateral forearm, wrist, and hand.
• Ulnar Artery: The ulnar artery runs medially along the forearm and supplies the medial forearm and hand.

Termination

The brachial artery ends in the cubital fossa, where it bifurcates into the radial and ulnar arteries. This bifurcation typically occurs near the neck of the radius bone. The radial and ulnar arteries then continue their courses down the forearm to supply blood to the forearm, wrist, and hand.

Relationship to Surrounding Structures

The brachial artery has several important relationships with nearby anatomical structures:

• Median Nerve: The median nerve runs alongside the brachial artery for much of its course in the arm. In the proximal arm, the nerve is lateral to the artery but crosses over to the medial side as it approaches the elbow. This close relationship is clinically significant, as injuries or procedures involving the brachial artery may also affect the median nerve.
• Muscles: The brachial artery lies medial to the biceps brachii muscle for most of its course, and its branches supply blood to the brachialis, coracobrachialis, and triceps brachii muscles. As the artery travels distally, it becomes superficial and is protected by the bicipital aponeurosis before entering the cubital fossa.
• Veins: The basilic vein runs parallel and superficial to the brachial artery in the upper arm. The brachial veins accompany the artery, usually as two veins (venae comitantes), which flank the artery and drain blood from the upper limb.
• Cubital Fossa: The artery’s position within the cubital fossa is clinically important due to its accessibility for pulse checks and medical procedures. Here, it lies between the median nerve (medial to the artery) and the biceps tendon (lateral to the artery).

Variations

The anatomy of the brachial artery can vary among individuals. Some common variations include:

• High Bifurcation: In some individuals, the brachial artery bifurcates higher in the arm, with the radial and ulnar arteries splitting above the elbow rather than in the cubital fossa.
• Accessory Branches: Some individuals may have additional or accessory branches arising from the brachial artery, which can alter the typical vascular pattern in the arm.

Function

The brachial artery plays a crucial role in supplying blood to the upper limb. As the main artery of the upper arm, it is responsible for delivering oxygenated blood to the arm’s muscles, bones, and other tissues. Its branches also ensure proper blood flow to the forearm, hand, and elbow. Below is a detailed description of the various functions of the brachial artery.

Blood Supply to the Anterior Compartment of the Arm

The brachial artery is the primary source of blood for the muscles in the anterior compartment of the arm. These muscles include:

• Biceps Brachii: The brachial artery supplies oxygenated blood to the biceps brachii muscle, which plays a key role in flexing the elbow and supinating the forearm.
• Brachialis: This muscle, which lies deep to the biceps, is responsible for flexing the elbow joint. The brachial artery provides the necessary blood supply for its function.
• Coracobrachialis: The artery also supplies blood to the coracobrachialis muscle, which helps flex and adduct the shoulder joint.

By delivering oxygen and nutrients to these muscles, the brachial artery ensures the arm can perform movements such as flexion at the elbow and movements at the shoulder joint.

Blood Supply to the Posterior Compartment of the Arm

Through its branch, the profunda brachii artery (deep artery of the arm), the brachial artery also provides blood to the muscles in the posterior compartment of the arm.

• Triceps Brachii: The profunda brachii artery supplies the triceps brachii muscle, which is responsible for extending the elbow. This ensures that both flexor and extensor muscles in the arm have adequate blood flow, enabling balanced arm movement.

Contribution to Elbow Joint Circulation

The brachial artery plays a key role in forming the collateral circulation around the elbow joint. Collateral circulation is crucial for maintaining blood flow to the forearm and elbow, especially when the joint is flexed, which can temporarily compress the main arterial pathways.

• Superior Ulnar Collateral Artery: This branch of the brachial artery runs alongside the ulnar nerve and forms an anastomosis (connection) with the posterior ulnar recurrent artery, providing an alternative route for blood flow during elbow movements.
• Inferior Ulnar Collateral Artery: This branch also contributes to the blood supply around the elbow by forming an anastomosis with the anterior ulnar recurrent artery. Together with the superior ulnar collateral artery, it helps maintain blood flow when the brachial artery is compressed during elbow flexion.
• Profunda Brachii Artery (Middle and Radial Collateral Branches): The branches of the profunda brachii artery contribute to the lateral aspect of the elbow’s circulation by forming anastomoses with the radial recurrent artery and interosseous recurrent artery, ensuring the posterior part of the elbow joint remains well-supplied with blood.

This robust network of collateral arteries ensures that the elbow joint and surrounding tissues receive adequate blood flow even when the primary arteries are compressed during arm flexion or movement.

Blood Supply to the Forearm and Hand

At the level of the elbow, the brachial artery bifurcates into the radial and ulnar arteries, which supply blood to the forearm and hand.

• Radial Artery: The radial artery supplies the lateral aspect of the forearm and continues into the hand, where it contributes to the formation of the deep palmar arch, supplying the deep muscles and bones of the hand.
• Ulnar Artery: The ulnar artery supplies the medial aspect of the forearm and also enters the hand, where it contributes to the formation of the superficial palmar arch, ensuring blood reaches the superficial muscles, tendons, and skin of the hand.

By giving rise to the radial and ulnar arteries, the brachial artery plays a critical role in the vascularization of the forearm and hand, ensuring proper blood flow to support various movements and functions.

Blood Supply to the Humerus

The brachial artery provides nutrient arteries that supply the humerus, the long bone of the upper arm.

Nutrient Artery to the Humerus: This small branch of the brachial artery enters the humerus through the nutrient foramen, delivering blood to the bone’s interior. This ensures that the bone tissue remains healthy and capable of growth, repair, and maintenance.

The nutrient artery is particularly important for bone healing after fractures, as it provides the necessary blood flow for osteogenesis (bone formation) and repair.

Oxygen and Nutrient Delivery

Like all arteries, the primary function of the brachial artery is to deliver oxygen and essential nutrients to the tissues it supplies. This is crucial for the health, maintenance, and repair of the muscles, bones, and connective tissues in the upper arm, elbow, and forearm.

• Tissue Repair and Healing: The brachial artery ensures that the muscles, tendons, and bones in the arm and forearm receive an adequate supply of oxygen and nutrients. This blood supply is particularly important for tissue repair after injury, muscle strain, or bone fractures.
• Maintenance of Muscle Function: Continuous blood flow from the brachial artery allows the muscles in the upper arm, including the biceps brachii, brachialis, and triceps brachii, to maintain their function and strength. Without proper blood flow, these muscles would become ischemic, leading to weakness or dysfunction.

Support for Nerve Function

The brachial artery runs in close proximity to several important nerves in the arm, particularly the median nerve and the ulnar nerve.

• Median Nerve: The median nerve runs alongside the brachial artery for much of its course. While the brachial artery does not directly supply the nerve, its close relationship ensures that the nerve remains well-nourished through nearby vascular branches, supporting nerve health and function in the arm and hand.
• Ulnar Nerve: The ulnar nerve is closely associated with the superior ulnar collateral artery, a branch of the brachial artery. This relationship helps maintain the health and function of the ulnar nerve as it passes through the arm and forearm, contributing to sensory and motor function in the hand.

Clinical Significance

The brachial artery is of significant clinical importance due to its role in supplying blood to the upper limb and its accessibility for medical procedures.

• Blood Pressure Measurement: The brachial artery is commonly used for blood pressure measurement. It is easily palpable in the cubital fossa, and this location provides an accurate assessment of arterial pressure in the upper limb.
• Vascular Access and Procedures: The brachial artery is frequently accessed for procedures such as arterial cannulation for monitoring arterial blood pressure, blood sampling, or performing angiography. Its superficial course in the arm makes it an ideal site for such interventions.
• Trauma and Injury: The brachial artery is vulnerable to injury, especially in cases of fractures of the humerus. Damage to this artery can lead to significant hemorrhage and may compromise blood supply to the arm, forearm, and hand, leading to ischemia if not treated promptly.
• Ischemic Conditions: The brachial artery is a key player in conditions like peripheral artery disease (PAD), where blockages or narrowing can lead to reduced blood flow to the arm and hand, resulting in pain, coldness, or even tissue damage.