Brachial Arteries

1. Overview

The brachial arteries are major blood vessels that supply oxygenated blood to the upper arm. They are the continuation of the axillary arteries and run down the arm, giving off branches to the muscles, bones, and tissues of the arm and forearm. The brachial arteries are essential for providing blood to the muscles and skin of the upper arm, as well as to the forearm and hand. They are often used in clinical settings for measuring blood pressure, as they are located in an accessible area of the body. The brachial arteries play a central role in maintaining proper circulation in the upper extremity and ensuring that the tissues and organs in the arm receive the oxygen and nutrients they need.

2. Location

The brachial arteries are located in the upper arm, starting as a continuation of the axillary artery at the inferior border of the teres major muscle (which forms the lower boundary of the axilla). The brachial arteries run down the arm along the medial side of the humerus, passing through the brachial sheath, a connective tissue structure that surrounds the artery and its accompanying veins and nerves. The brachial artery travels in the anterior compartment of the arm, where it is close to the biceps brachii and the coracobrachialis muscles. The brachial artery eventually bifurcates at the elbow into the radial and ulnar arteries, which supply blood to the forearm and hand.

3. Structure

The brachial arteries are large, muscular arteries that are structurally designed to handle the high-pressure blood flow coming from the heart. Some key structural features of the brachial arteries include:

• Size and Length: The brachial arteries are relatively large, measuring approximately 0.5 to 1 cm in diameter, depending on the individual. They are approximately 25-30 cm in length, running from the inferior border of the teres major muscle to the bifurcation at the elbow.

• Walls: Like other arteries, the brachial arteries have three layers: the innermost layer, the intima, is made up of endothelial cells that line the artery and provide a smooth surface for blood flow; the middle layer, the media, contains smooth muscle cells and elastic tissue that allow the artery to expand and contract with each heartbeat; the outer layer, the adventitia, is made of connective tissue that provides structural support to the artery.

• Branching: As the brachial arteries travel down the arm, they give off several branches to supply blood to the muscles, skin, and bones of the upper arm. Some of the major branches of the brachial artery include:

  • Profunda brachii artery: This large branch supplies blood to the muscles of the posterior arm and the elbow joint.

  • Superior ulnar collateral artery: This artery provides blood to the elbow joint and the surrounding tissues.

  • Inferior ulnar collateral artery: This artery supplies blood to the muscles and tissues around the elbow joint.

• Bifurcation: At the elbow, the brachial artery bifurcates into two main branches: the radial artery and the ulnar artery. These arteries supply blood to the forearm and hand, with the radial artery traveling along the lateral side and the ulnar artery traveling along the medial side of the forearm.

4. Function

The primary function of the brachial arteries is to supply oxygenated blood to the upper arm and forearm. This includes delivering blood to the muscles, skin, bones, and tissues of the upper extremity. Some of the key functions of the brachial arteries include:

• Blood supply to the upper arm: The brachial arteries provide blood to the muscles of the upper arm, including the biceps brachii, triceps brachii, and other smaller muscles. This blood supply is essential for muscle function, including movement and strength, as well as for maintaining tissue health and oxygen exchange.

• Blood supply to the forearm and hand: The brachial arteries give rise to the radial and ulnar arteries, which supply blood to the forearm and hand. These arteries ensure that the muscles, bones, skin, and tissues of the lower arm and hand receive the necessary oxygen and nutrients required for movement, dexterity, and metabolic processes.

• Regulation of blood pressure: As part of the systemic circulation, the brachial arteries help maintain blood pressure in the upper limbs by providing a continuous flow of blood from the heart to the tissues of the arm. The elasticity of the artery walls helps regulate the pulse pressure generated by the heart and ensures steady blood flow during both systole and diastole.

• Support of arm movement: The brachial arteries supply blood to muscles responsible for movements such as lifting, gripping, and reaching. Adequate blood supply ensures that these muscles can function efficiently and sustain prolonged activity without fatigue or ischemia (lack of oxygen).

5. Physiological Role(s)

The brachial arteries have several key physiological roles that are important for the health and functioning of the upper extremities:

• Muscle function: The brachial arteries supply blood to the muscles of the arm, which are essential for both fine motor tasks (e.g., writing, typing) and gross motor tasks (e.g., lifting, carrying). Proper blood flow ensures that muscles can function effectively and remain energized during physical activity.

• Tissue oxygenation: The brachial arteries ensure that oxygenated blood reaches the tissues of the arm, including skin, muscles, and connective tissue. Oxygen is vital for cellular respiration and energy production in the tissues, and a constant supply of oxygenated blood is necessary to maintain cellular function.

• Regulation of venous return: By supplying blood to the muscles and tissues of the upper extremity, the brachial arteries help support venous return from the arm. This ensures that deoxygenated blood is efficiently transported back to the heart via the venous system, preventing blood pooling and maintaining circulatory efficiency.

• Adaptation during physical activity: The brachial arteries play a key role in adapting to increased blood flow during exercise or physical exertion. By expanding and allowing more blood to flow to the muscles, the brachial arteries support the increased metabolic demands of the upper extremity during activities like running, lifting, or climbing.

6. Clinical Significance

The brachial arteries are clinically significant because they are essential for maintaining blood supply to the arm and forearm. Several conditions can affect the brachial arteries, leading to impaired circulation, tissue damage, or other complications. Some key clinical conditions related to the brachial arteries include:

• Brachial artery aneurysm: A brachial artery aneurysm occurs when there is a localized dilation of the artery due to weakening of the arterial wall. This condition can lead to reduced blood flow and increase the risk of clot formation. If left untreated, an aneurysm may rupture, causing severe bleeding. Treatment often involves surgical repair or stenting.

• Atherosclerosis: Atherosclerosis (the buildup of fatty deposits or plaque in the artery walls) can affect the brachial arteries, leading to narrowing or obstruction of the vessels. This condition can reduce blood flow to the arm, causing symptoms such as pain, cramping, and weakness. Treatment may involve lifestyle changes, medications, or surgical intervention to clear the blockage and restore blood flow.

• Peripheral artery disease (PAD): PAD is a condition in which the arteries supplying blood to the limbs become narrowed or blocked. PAD can affect the brachial artery, leading to symptoms such as pain or cramping in the arms during physical activity. PAD is commonly caused by atherosclerosis and can be managed with lifestyle changes, medications, or surgical procedures like angioplasty or bypass surgery.

• Trauma or injury: The brachial artery can be injured in cases of trauma, such as fractures or deep lacerations in the upper arm. Damage to the brachial artery can result in hemorrhage and reduced blood supply to the forearm and hand. Immediate medical attention is necessary to repair the artery and restore circulation.

• Brachial artery dissection: A dissection of the brachial artery occurs when there is a tear in the inner layer of the artery wall, causing blood to flow between the layers of the vessel. This can lead to reduced blood flow, pain, and potentially more severe complications. Treatment typically involves surgery or endovascular procedures to repair the tear.

The brachial arteries are essential for maintaining blood supply to the upper limbs and ensuring efficient circulation throughout the arm. Conditions that affect the brachial arteries, such as aneurysms, atherosclerosis, or trauma, can lead to significant complications. Early diagnosis, prevention, and treatment are crucial for maintaining optimal upper limb function and cardiovascular health.