The body’s circulatory system relies on a continuous network of vessels to deliver oxygenated blood, and the arm contains major arteries supplying the entire upper limb. Understanding the path of these vessels is helpful, especially in emergency situations or when discussing medical procedures. The main arterial trunk travels from the shoulder down the arm, branching near the elbow to supply the structures of the forearm and hand. Knowing the anatomical location of these vessels explains why certain spots on the arm are used for taking a pulse or measuring blood pressure.
The Brachial Artery The Main Pathway
The brachial artery is the primary artery supplying the arm. It is a direct continuation of the axillary artery after passing the lower border of the teres major muscle near the shoulder. This vessel delivers oxygen-rich blood to the entire upper extremity. It courses down the inner surface of the upper arm, running parallel to the median nerve.
As the artery descends, it follows the path of the humerus bone, positioned initially on the medial side of the arm. The overlying biceps brachii muscle protects the artery from superficial injury. It gives off several branches along its route, including the deep brachial artery, which supplies the muscles in the posterior compartment of the arm.
The brachial artery reaches the cubital fossa, the triangular indentation at the front of the elbow. In this region, the artery lies just medial to the tendon of the biceps muscle. This location marks the end of the brachial artery’s course, where it divides into its two terminal branches to supply the structures below the elbow.
Arteries of the Forearm and Hand
The arterial supply transitions in the cubital fossa, where the brachial artery bifurcates into the radial artery and the ulnar artery. These two terminal branches descend through the forearm, supplying the muscles and tissues down to the fingertips. The radial artery begins its path along the lateral aspect of the forearm, closer to the thumb.
The radial artery runs deep to the brachioradialis muscle for much of its course, lying on the radius bone. In the distal third of the forearm, it becomes more superficial, positioned between the brachioradialis tendon and the flexor carpi radialis tendon near the wrist. The ulnar artery takes a path along the medial side of the forearm, closer to the little finger.
The ulnar artery begins with a deeper course, passing beneath the pronator teres muscle, before traveling between the layers of the flexor muscles. It eventually emerges in the distal forearm alongside the ulnar nerve. In the hand, both the radial and ulnar arteries contribute to a network of vessels, forming the deep palmar arch and the superficial palmar arch. These arches ensure continuous blood flow and supply the individual fingers.
Why Artery Location Matters
Knowledge of arterial locations is applied in medicine and first aid situations. The placement of the brachial artery in the cubital fossa, medial to the biceps tendon, makes it the standard site for routine blood pressure measurements. A healthcare provider uses a stethoscope over this spot to listen for the characteristic sounds of blood flow returning to the artery after a blood pressure cuff is released.
The radial artery’s superficial position near the wrist makes it the most common site for checking a pulse. The vessel lies just under the skin at the base of the thumb, making its rhythmic pulsations easily detectable. A less common but important pulse point is the brachial pulse, felt in the crease of the elbow, which is often used to assess circulation in infants.
In situations of severe upper limb bleeding, knowing the path of the main artery is important for hemorrhage control. Applying firm pressure directly over the brachial artery high up on the inner arm can temporarily reduce blood flow to the entire limb. This anatomical understanding allows for targeted interventions, such as emergency care or surgical access, including catheter insertion into the radial artery for heart procedures.