Where Is the Brachial Located on the Human Body?

The term “brachial” refers to the upper arm, the segment between the shoulder and the elbow. When people ask where the brachial is located, they are usually asking about the brachial artery or the brachial plexus, both of which sit in or pass through this region and come up constantly in medicine. The brachial artery runs along the inner side of the upper arm, while the brachial plexus is a network of nerves that originates from the neck and extends through the shoulder into the arm. Together, they supply nearly all the blood and nerve signals your arm needs to function.

The Brachial Artery and Its Course

The brachial artery is the main blood vessel of the upper limb. It begins at the lower edge of the teres major muscle near the armpit, where it picks up as a continuation of the axillary artery, and it travels down the inner side of the upper arm. You can often feel its pulse by pressing gently on the soft tissue along the inside of your biceps, roughly midway between the shoulder and elbow. It ends just below the elbow crease at the level of the neck of the radius bone, where it splits into two smaller arteries: the radial artery, which continues toward the thumb side of the wrist, and the ulnar artery, which runs toward the pinky side.¹

Along the way, the brachial artery sends off several branches to keep surrounding tissues fed. The profunda brachii (also called the deep artery of the arm) curves behind the humerus bone to supply the triceps and the back of the arm. Superior and inferior ulnar collateral branches head toward the elbow, where they form a web of connections that help maintain blood flow even if the main vessel is temporarily compressed, such as when you lean on your elbow.¹ This collateral network is one reason you can bend and straighten your arm repeatedly without cutting off circulation to your hand.

Why Doctors Care About Your Brachial Artery

If you have ever had your blood pressure taken with a cuff, the brachial artery is the vessel being measured. The cuff inflates around your upper arm, temporarily stopping blood flow through the brachial artery, and the reading is taken as pressure is slowly released. Brachial cuff blood pressure has been the clinical standard for decades, and a detailed analysis in the American Journal of Hypertension concluded that there is no compelling reason to replace it with newer central-pressure measurements for the vast majority of patients.² Central blood pressure readings from the aorta may occasionally add value in specialized heart and aortic diseases, but for routine check-ups, the brachial measurement remains the go-to.

The brachial artery also serves as an access point when clinicians need a direct arterial blood sample, most often to check blood oxygen and carbon dioxide levels. While the radial artery at the wrist is more commonly used, brachial artery puncture is considered a safe and reliable alternative when the radial pulse is hard to find or when repeated samples are needed.³ In intensive care, the brachial artery is one of several sites where a thin catheter can be inserted for continuous blood pressure monitoring and frequent blood gas draws.⁴

The Brachial Plexus

The brachial plexus is a bundle of nerves that controls movement and sensation in your shoulder, arm, and hand. It forms from spinal nerve roots in the lower neck and upper back, specifically from the fifth cervical vertebra down to the first thoracic vertebra (commonly written as C5 through T1). These roots emerge from the spinal cord, merge and split into trunks, divisions, and cords, and ultimately give rise to the individual nerves you may have heard of: the musculocutaneous nerve, the median nerve, the ulnar nerve, and the radial nerve, among others.⁵

Microscopically, each root originates from the spinal cord at slightly different distances from the midline. Detailed cadaveric measurements show that the closest a root sits to the midline is about 2.2 mm at the C5 level, while the farthest is about 3.1 mm at T1 for the anterior roots, with the posterior roots following the opposite trend.⁶ These millimeter-level differences matter to surgeons operating near the spinal cord, but for practical purposes, the key point is that the plexus originates from the neck and threads through the space between the collarbone and first rib before spreading into the arm.

Muscles of the Brachial Region

The upper arm is divided into two compartments by sheets of connective tissue called intermuscular septa, plus the humerus bone itself. The front (anterior) compartment houses the flexor muscles, while the back (posterior) compartment contains the extensors.⁷

In the anterior compartment, the biceps brachii is the most familiar muscle. Underneath it sits the brachialis, a powerful elbow flexor that does more of the heavy lifting than most people realize. The coracobrachialis, a smaller muscle near the top, helps pull the arm forward and inward. These muscles are typically supplied by the musculocutaneous nerve, though anatomical dissections occasionally reveal variants where the median nerve takes over that job entirely.⁸ The existence of such variants underscores why surgeons rely on imaging and nerve stimulation rather than textbook diagrams alone during arm procedures.

The posterior compartment is dominated by the triceps brachii, the three-headed muscle responsible for straightening the elbow. Its long head originates from the shoulder blade, while the lateral and medial heads arise from the humerus. The triceps gets its nerve supply from the radial nerve and its blood supply from the profunda brachii artery, the same deep branch of the brachial artery mentioned earlier.⁹ The medial head of the triceps has gained surgical interest as a potential tissue donor for reconstructive procedures, averaging roughly 10.7 cm in length and weighing about 30 grams, with a reliable blood supply that makes transplantation feasible.¹⁰

The Cubital Fossa and Blood Draws

The cubital fossa is the shallow depression on the front of the elbow where the brachial artery’s terminal split occurs. It is also where most blood draws and IV insertions happen. A detailed study of 128 cadaveric arms found that the veins in this region follow one of several patterns, but the median cubital vein, which angles between the cephalic and basilic veins, is usually the safest and easiest target for a needle.¹¹

The brachial artery and a network of cutaneous nerves lie just beneath these veins, so accuracy matters. About one in five arms in that same study had a superficial brachial artery running unusually close to the surface under the median cubital vein.¹¹ Accidentally puncturing the artery instead of a vein is generally obvious because arterial blood is bright red and pulses, but it can cause bruising or a hematoma if not caught quickly. This is one reason phlebotomists prefer the middle-to-outer part of the median cubital vein, which tends to sit farther from the artery and the medial cutaneous nerve.

Anatomical Variations Worth Knowing About

The brachial artery does not look the same in everyone. According to the literature, it deviates from the textbook pattern in roughly one in five people.¹² The most common variant is a high bifurcation, where the artery splits into its radial and ulnar branches somewhere in the upper arm rather than waiting until the elbow. One ultrasound-based study of 481 patients found high bifurcation in about 12% of arms, with no significant differences based on race, sex, or side of the body.¹³

This variation matters for several practical reasons. If a surgeon creating a dialysis access fistula or a radiologist performing an angiogram assumes the split happens at the elbow, they could accidentally damage or bypass a vessel they did not expect. Pre-procedure imaging, especially ultrasound-based vascular mapping, can flag the variant before any incision or needle insertion is made.¹³ A rarer finding involves an accessory brachial artery, an extra vessel that branches off, takes a separate course, and then rejoins the main trunk near the elbow. Cadaveric studies have documented this in about 7% of specimens.¹⁴

Brachial Plexus Injuries

Because the brachial plexus threads through a relatively exposed corridor between the neck and the arm, it is vulnerable to injury. A large surgical series of over 1,000 brachial plexus injuries found that roughly half were stretch or contusion injuries, the kind that happen in motorcycle crashes, falls from heights, or sports collisions. Gunshot wounds accounted for about 12%, and sharp or blunt lacerations (from knives, glass, or machinery) made up another 7%.¹⁵ Among non-traumatic causes in that same series, thoracic outlet syndrome (where the nerves are compressed in the space between the collarbone and first rib) accounted for 16%, and tumors of the nerve sheath made up another 16%.¹⁵

Not all brachial plexus injuries involve dramatic trauma. A case report documented brachial plexus palsy in a patient who had simply passed out from alcohol intoxication and remained in one position for an extended period, compressing the nerves under body weight.¹⁶ This is sometimes called “Saturday night palsy” in informal medical slang. The takeaway is that prolonged, unrelieved pressure on the upper arm or shoulder area can damage these nerves even without a direct blow.

Brachial Plexus Blocks in Surgery

Surgeons and anesthesiologists frequently target the brachial plexus to numb the arm for operations on the elbow, forearm, or hand. Rather than putting a patient fully under general anesthesia, a local anesthetic is injected around the plexus at one of several approach points: above the collarbone (supraclavicular), below the collarbone (infraclavicular), or in the armpit (axillary). A randomized trial comparing all three approaches found that using ultrasound guidance to visualize the nerves and watch the anesthetic spread achieved surgical-level numbness in 99% of patients, compared with 91% when nerve stimulation alone was used to locate the plexus.¹⁷

A study comparing the three ultrasound-guided block approaches using 20 mL of ropivacaine confirmed that each technique could provide reliable surgical anesthesia for procedures below the shoulder, though the speed of onset and the specific nerves blocked first varied depending on where the injection was placed.¹⁸ The ability to keep a patient awake and comfortable while only numbing the arm has real advantages: less nausea, faster recovery, and better pain control in the hours after surgery.

Lymph Nodes Along the Upper Arm

The brachial region also contains lymph nodes that are less well known than the ones in the armpit but clinically relevant, especially in breast cancer care. Two groups sit along the upper arm: the epitrochlear nodes near the inner elbow and the humeral (or lateral axillary) nodes higher up along the brachial vessels. A study using lymphatic imaging found that drainage to epitrochlear nodes occurred in 57% of arms, and drainage to humeral nodes in 51%. About a third of arms showed no drainage to either set of nodes at all.¹⁹

This variability has implications for lymphedema, the chronic arm swelling that can develop after breast cancer surgery when axillary lymph nodes are removed. If a patient’s deep lymphatic system already routes through the humeral and epitrochlear nodes, disruption of the axillary nodes may be partially compensated. The presence or absence of these brachial lymph nodes could eventually help predict which patients are at higher risk of developing lymphedema after treatment, though this line of research is still evolving.

How the Brachial Artery Forms Before Birth

The arterial system of the arm does not appear fully formed. A study of 112 human embryos (224 upper limbs) traced the process from its earliest stages. It begins with a mesh of tiny capillaries sprouting from the dorsal aorta during early embryonic development. Over subsequent stages, selected channels in this mesh enlarge while others disappear, a process that moves from the body’s core outward. By roughly the fifth week of development, the differentiation has reached the subclavian and axillary arteries. By the sixth week, the brachial artery is recognizable down to the elbow. By the seventh to eighth week, the full adult pattern, including the radial and ulnar arteries in the forearm, is in place.²⁰

This remodeling process runs in parallel with skeletal development, meaning the bones and blood vessels of the arm are shaping each other’s paths simultaneously. Disruptions during this window can explain the anatomical variants seen in adults, including the high bifurcations described earlier. When the remodeling process selects an atypical channel for enlargement, the adult ends up with a brachial artery that splits higher than expected, or an accessory vessel that would not be in any standard anatomy textbook.¹²

The Brachial Region Across Primates

Humans are not the only species with a brachial plexus, and comparing our version with those of other primates reveals how much arm anatomy is shaped by how a species moves. Old world monkeys and new world monkeys share more similarities in their brachial plexus organization with each other than either group shares with humans, likely because both groups use their forelimbs in broadly similar ways during locomotion, while human arms have been freed from weight-bearing by upright walking.²¹ Quantitative studies of arm bone dimensions across 39 primate genera confirm that while humans resemble different non-human primate groups in different specific measurements, the overall combination of features in the human brachial region is unique. This uniqueness reflects a limb that evolved for manipulation rather than suspension or quadrupedal support.²²

The practical takeaway from comparative work is that our brachial anatomy carries evolutionary compromises. The plexus threads through a tight corridor between the clavicle and first rib partly because our shoulders rotated to allow overhead reaching and throwing. That same corridor makes the nerves vulnerable to compression and stretch injuries in ways that a quadrupedal animal, whose forelimb bears weight in a different orientation, would rarely experience.