The Anatomy Of The Brachial Artery

                  The Anatomy Of The Brachial Artery

The brachial artery commences at the lower margin of the tendon of the Teres major, and, passing down the arm, ends about 1 cm. below the bend of the elbow, where it divides into the radial and ulnar arteries. At first, the brachial artery lies medial to the humerus, but as it runs down the arm it gradually gets in front of the bone, and at the bend of the elbow it lies midway between its two epicondyles. This article shall discuss the anatomy of the brachial artery.

The brachial artery is one of the most important sources of blood to the arm and hand ( in addition to the axillary and subclavian arteries) and is an essential component of the circulatory system. It is the continuation of the subclavian and axillary arteries and is found in the arm between the teres major muscle and the elbow.

Anatomy

The brachial artery is the main artery of the arm. It’s a continuation of the axillary artery.

Structure

Moving from the shoulder down, the brachial artery splits into several important branches, which are essential in providing blood and nutrients to muscle and tissue groups there.

• • Profunda brachial artery: An important, deeper artery, the profunda brachii arises just below the shoulder’s Teres major muscle and follows the radial nerve, which provides signals and messaging to the triceps on the back of the arm. It provides blood to the deltoids, wrapping around the triceps.
  • Superior ulnar collateral artery: Splitting off a little more than halfway between the shoulder and elbow, this artery provides blood to the biceps.
  • Inferior ulnar collateral artery: At about 5 centimeters above the elbow, the inferior ulnar collateral artery winds around the humerus—the long upper arm bone—and rests between the triceps and the bone structure.
  • Ulnar artery: Starting at the cubital fossa at the end of the brachial artery, the ulnar artery runs through the second and third layers of the flexor muscles in the forearm. It then proceeds above the flexor retinaculum at the wrist, a fibrous band that bends over the carpal bones to form the carpal tunnel and becomes the superficial palmar branch, a major source of blood for the hand.
• Radial artery: The brachial artery also terminates into the radial artery, which proceeds under the brachioradialis muscle, which is what allows the wrist to bend backward. It also runs laterally to the flexor carpi radialis muscle, which is involved in hand and wrist motion. This artery provides blood to both flexor (back-bending) and extensor (forward-bending) compartments of the forearm.

Location

A continuation of the axillary artery in the shoulder, the brachial artery runs along the underside of the upper arm, terminating about a centimeter past the elbow joint.

Largely this artery is just below the skin as well as both superficial and deep fascia, which are layers of dense, connective tissue. It runs alongside the humerus, the upper arm bone. In the elbow, the artery, alongside the medial cubital vein and bicep tendon, forms the cubital fossa, a triangular pit on the inside of the elbow.

Variation

Like all parts of the vascular system, there is a variation from person to person. Sometimes the brachial artery runs more medially—that is more towards the middle—of the elbow, accessing the medial epicondyle of the humerus, which is the rounded part of the bone. In these cases, the positioning of the artery is more towards the middle, and it runs behind the supracondylar process of the humerus, a bony projection about five centimeters above the elbow joint.

One common variation is when there are high bifurcations of the brachial artery in the upper arm.

In addition, this artery can form branches that are more proximal, or further up the arm than usual. In these instances, three branches split off from the brachial artery, the ulnar, radial, and common interosseous arteries, with the radial artery splitting off earlier on.

Understanding the variations in this anatomy is particularly important for surgeons providing care.

Function

The brachial artery is primarily involved with providing oxygenated blood to the arm and hand. As such, it’s essential for nearly every aspect of upper limb mobility, ensuring that muscle groups and tendons are supplied with the nutrients necessary for proper function.

Surgeons may also need to apply compression of the brachial artery to control blood loss in trauma patients. This is done proximal (above) to the site of injury to stop the flow of blood until the patient gets to the operating room. The longer a tourniquet is inflated, the higher the risk of tissue loss.

Clinical Significance

Because the brachial artery serves such an important role in providing blood to the upper limbs, it can be involved in a number of disorders or conditions. In addition, it can be affected by injury to the area and, in fact, is the most often injured artery of the upper body due to its vulnerability.

The brachial artery is also used for dialysis access procedures and is sometimes used as an access point for endovascular procedures in patients with aneurysms or peripheral arterial disease. Atherosclerosis of the brachial artery may be seen in patients with diabetes or chronic kidney disease.

Supracondylar Fracture of the Humerus Shaft

Especially common in children, supracondylar fracture of the humerus shaft occurs due to falls on the elbow or extended hand. This can cause displacement of the distal fragment—the part of the bone further away from the body—in the humerus, which can damage the brachial artery.

In general, fractures or nerve problems in the upper arm can affect the functioning of the brachial artery.

Peripheral Artery Disease

The ankle-brachial index measures blood pressure in the ankle as well as the brachial artery to test for peripheral artery disease (PAD) in a non-invasive manner. PAD is when one or more arteries that supply blood to the limbs become blocked, most often due to atherosclerosis, or the build-up of plaque in vessels.

Ischaemic Compartment Syndrome

Swelling can occur when there’s a severe injury to the arm, which raises the amount of compression on the brachial artery and surrounding nerves and muscles. With ischaemic compartment syndrome, scarring starts in the injured area—anywhere from 30 minutes to 12 hours after injury—leading to permanent shortening of muscles. This can cause pain, paralysis, and paraesthesia (the sensation of “pins and needles”) in the area.

Volkmann’s Ischaemic Contracture

This is a permanent contracture of the hand at the wrist. Causes vary, but damage or the blocking of the brachial artery can lead to the condition.1 It can also result from ischaemic compartment syndrome.

Aneurysm

The most common causes of brachial artery aneurysms are pseudoaneurysms after brachial artery injury during an IV attempt, infectious aneurysms from septic emboli, or brachial artery aneurysms following dialysis access.

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