Deep Artery of the Arm

The deep artery of the arm, also known as the profunda brachii artery, is the largest branch of the brachial artery. It is responsible for supplying blood to the posterior (extensor) compartment of the arm, including the triceps brachii muscle, and also contributes to the blood supply of the elbow joint through an extensive network of collateral vessels. The profunda brachii artery plays a crucial role in maintaining circulation in the upper arm and forearm, especially during elbow flexion and extension.

Location

The deep artery of the arm arises from the brachial artery, typically near the proximal part of the arm, just below the lower border of the teres major muscle. It travels posteriorly, following a course that runs alongside the radial nerve in the radial groove of the humerus. The artery descends along the back of the humerus, supplying blood to the posterior arm muscles, primarily the triceps brachii. It continues distally, giving off branches that contribute to the collateral circulation around the elbow joint before eventually anastomosing with other arteries in the forearm.

Structure and Anatomy

The deep artery of the arm, also known as the profunda brachii artery, is the largest and most important branch of the brachial artery. It provides blood supply to the posterior compartment of the upper arm and plays a critical role in forming collateral circulation around the elbow. Below is a detailed description of the anatomy of this artery.

Origin

The deep artery of the arm typically arises from the brachial artery near its proximal part. The origin is usually located just below the lower border of the teres major muscle, which is where the brachial artery begins its descent through the arm. In some individuals, the profunda brachii may arise slightly higher or lower on the brachial artery, but this is the most common location.

Course

The profunda brachii artery follows a posterior course along the upper arm, supplying the muscles and bones in this region. Its trajectory is closely associated with the radial nerve, as both structures travel through the radial groove of the humerus.

Proximal Course

After arising from the brachial artery, the profunda brachii artery immediately travels posteriorly, entering the posterior compartment of the arm. It accompanies the radial nerve, wrapping around the back of the humerus within the radial (spiral) groove. This groove is located on the posterior surface of the humerus and provides a pathway for both the radial nerve and the profunda brachii artery.

Relationship with Radial Nerve: As the artery courses through the radial groove, it remains in close proximity to the radial nerve, which innervates the muscles of the posterior compartment of the arm.

Distal Course

As the profunda brachii artery continues its descent along the posterior aspect of the arm, it supplies blood to the triceps brachii muscle. It travels towards the distal end of the humerus, where it eventually divides into two terminal branches: the middle collateral artery and the radial collateral artery.

Branches

The deep artery of the arm gives rise to several important branches as it descends through the posterior arm. These branches supply the muscles and tissues of the upper arm and contribute to the collateral circulation around the elbow.

Muscular Branches

Throughout its course, the profunda brachii artery gives off several muscular branches that supply the triceps brachii muscle, the primary muscle of the posterior compartment of the arm. The triceps brachii is responsible for extension of the elbow joint, and the muscular branches ensure that this large muscle receives an adequate blood supply.

Deltoid Branch

The profunda brachii artery may give off a small branch that supplies the deltoid muscle. This branch typically arises from the proximal part of the artery, near its origin from the brachial artery.

Middle Collateral Artery

One of the two terminal branches of the profunda brachii artery is the middle collateral artery. This artery descends along the posterior aspect of the distal humerus, running towards the elbow joint. It plays an important role in the collateral circulation around the elbow by forming anastomoses with other arteries that supply the joint.

Radial Collateral Artery

The other terminal branch is the radial collateral artery, which travels alongside the radial nerve toward the lateral side of the elbow. This artery also contributes to the blood supply of the elbow joint by anastomosing with the radial recurrent artery and other arteries in the area.

Termination

The profunda brachii artery terminates by dividing into its two terminal branches:

• Middle Collateral Artery: This artery anastomoses with other arteries around the posterior part of the elbow joint, contributing to the collateral circulation that ensures adequate blood flow during flexion and extension of the elbow.
• Radial Collateral Artery: The radial collateral artery descends on the lateral side of the arm and elbow, eventually forming an anastomosis with the radial recurrent artery, a branch of the radial artery. This anastomosis is part of the vascular network that supplies the lateral aspect of the elbow.

Relationship to Surrounding Structures

The profunda brachii artery has important anatomical relationships with several key structures in the upper arm:

• Radial Nerve: As previously mentioned, the artery runs in close proximity to the radial nerve as they both pass through the radial groove of the humerus. This relationship is important because any injury to the humerus that affects the radial nerve may also compromise the artery.
• Humerus: The artery runs along the posterior surface of the humerus, following the radial groove. Its position close to the bone makes it vulnerable in fractures of the humeral shaft.
• Triceps Brachii Muscle: The profunda brachii artery provides blood supply to the triceps brachii muscle through its muscular branches. This large muscle forms the bulk of the posterior compartment of the upper arm and relies on the artery for nourishment.

Variations

While the profunda brachii artery typically follows a standard course, there can be some anatomical variations:

• High Origin: In some individuals, the profunda brachii artery may arise higher on the brachial artery, or it may even arise directly from the axillary artery.
• Multiple Branches: In rare cases, the artery may give off additional branches or divide earlier than usual, creating more extensive collateral networks.

Function

The deep artery of the arm, or profunda brachii artery, plays a crucial role in the vascular supply of the posterior compartment of the arm and in forming part of the collateral circulation around the elbow. Below is a detailed explanation of its specific functions.

Blood Supply to the Posterior Compartment of the Arm

The primary function of the profunda brachii artery is to provide blood to the muscles in the posterior compartment of the upper arm, which is crucial for arm extension and overall arm strength.

• Triceps Brachii Muscle: The profunda brachii artery supplies the triceps brachii, the main extensor muscle of the forearm. This muscle is responsible for extending the elbow joint and enabling movements such as pushing, throwing, and lifting. Through its muscular branches, the artery ensures that the triceps brachii muscle receives adequate oxygenated blood, allowing it to perform these critical functions.
• Anconeus Muscle: The artery also contributes to the blood supply of the anconeus muscle, a small muscle near the elbow that assists the triceps brachii in extending the elbow and stabilizing the joint during movement.

Contribution to Collateral Circulation Around the Elbow

One of the most important functions of the profunda brachii artery is its role in forming the collateral circulation around the elbow joint. This system of vessels ensures that the elbow joint and surrounding muscles receive an uninterrupted blood supply, even during flexion and extension when the main arterial pathways may be compressed or blocked.

• Middle Collateral Artery: The profunda brachii artery gives rise to the middle collateral artery, which travels along the posterior aspect of the distal humerus and anastomoses (connects) with the interosseous recurrent artery around the posterior part of the elbow. This helps to supply blood to the elbow joint during movement, especially when the brachial artery may be temporarily compressed due to flexion.
• Radial Collateral Artery: Another major branch, the radial collateral artery, supplies the lateral aspect of the elbow. It forms anastomoses with the radial recurrent artery, a branch of the radial artery. This connection ensures that blood flow to the lateral elbow is maintained even during movements that stretch or compress the vessels.

These collateral branches work together to maintain continuous blood flow around the elbow, preventing ischemia (lack of blood supply) in the joint and surrounding muscles during intense physical activities.

Blood Supply to the Humerus

In addition to supplying muscles, the profunda brachii artery plays a role in delivering blood to the humerus, the long bone of the upper arm.

Periosteal Blood Supply: The artery provides small branches that nourish the periosteum (the outer covering of the bone) of the humerus, particularly along the posterior aspect where the artery runs through the radial groove. This blood supply is essential for the maintenance and repair of bone tissue, especially in response to stress or fractures.

Support for Radial Nerve Function

The profunda brachii artery runs in close proximity to the radial nerve as both structures travel through the radial groove of the humerus. While the artery itself does not supply the nerve directly, its close anatomical relationship ensures that any disruption to the artery could impact the radial nerve.

Radial Nerve Function: The radial nerve controls the muscles responsible for extending the forearm, wrist, and fingers. The artery’s role in supplying the muscles innervated by the radial nerve (such as the triceps brachii) ensures that the muscles remain functional and well-nourished. If the artery or nerve is compromised due to trauma or injury, both the vascular supply and nerve function could be affected.

Oxygen and Nutrient Delivery to Posterior Arm Tissues

Like all arteries, the profunda brachii artery’s fundamental role is to deliver oxygen and nutrients to the tissues it supplies. This is essential for the health and maintenance of muscles, bones, and connective tissues in the posterior arm.

• Tissue Repair and Regeneration: By delivering oxygenated blood to the muscles, bone, and connective tissues of the arm, the profunda brachii artery supports the repair and regeneration of these tissues after injury or stress. This is particularly important for the triceps muscle, which is subjected to repetitive use in many physical activities.
• Muscle Maintenance: Continuous blood flow from the artery ensures that the triceps brachii and other muscles in the posterior arm receive the necessary nutrients to maintain their strength, size, and functionality, allowing the arm to perform a wide range of motions.

Support During Physical Activity

The profunda brachii artery plays a vital role in maintaining arm function during physical activity. By supplying the muscles and bones of the posterior arm, the artery enables efficient arm extension, elbow stability, and overall arm strength.

• Elbow Extension: As the primary extensor muscle of the elbow, the triceps brachii relies on the profunda brachii artery for a consistent blood supply during repetitive or forceful arm extensions, such as pushing movements in sports, lifting, or daily activities.
• Elbow Stability: The collateral branches of the artery also ensure that the elbow joint remains stable and well-nourished during flexion and extension, preventing joint damage and allowing for smooth, coordinated movements.

Clinical Significance

The profunda brachii artery plays a crucial role in supplying blood to the posterior compartment of the upper arm and contributing to the collateral circulation around the elbow joint. Its clinical significance includes:

• Fractures of the Humerus: The profunda brachii artery runs in close proximity to the radial groove of the humerus, making it vulnerable to injury in cases of midshaft humeral fractures. Damage to this artery can lead to significant bleeding and compromise the blood supply to the posterior arm muscles. Additionally, its close relationship with the radial nerve means that both the artery and nerve are at risk in such fractures, potentially causing nerve damage and loss of arm function.
• Collateral Circulation: The profunda brachii artery is important for maintaining blood flow around the elbow joint, especially during movement. In cases of arterial blockages in the brachial artery, the collateral circulation provided by the profunda brachii and its branches helps preserve blood flow to the distal arm and forearm.
• Surgical Importance: Surgeons need to be aware of the profunda brachii artery during procedures on the arm, such as fracture repairs or treatments involving the elbow, to avoid damaging this important vessel. Preservation of the artery is crucial to maintain proper circulation in the arm.