Erb’s Point is a term used in medicine and anatomy to describe two distinct locations on the human body. One point, located in the neck, relates to neurology and the shoulder. The other, on the chest, is used in cardiology for listening to the heart. Both locations are named after the German neurologist Wilhelm Heinrich Erb. Understanding the anatomical position and function of each Erb’s Point is necessary for diagnosis and clinical practice.
The Anatomical Location in the Neck
The neurological definition of Erb’s Point refers to a specific junction of nerves in the lateral aspect of the neck, situated just above the collarbone. This point is located approximately 2 to 3 centimeters superior to the clavicle, positioned near the posterior edge of the sternocleidomastoid muscle. It lies within the supraclavicular fossa, a slight depression in the shoulder area.
This location marks where the fifth and sixth cervical nerve roots (C5 and C6) converge to form the upper trunk of the brachial plexus. The brachial plexus is a network of nerves that transmits signals for movement and sensation to the arm, forearm, and hand. Because multiple nerve fibers meet here, this small area is vulnerable to external trauma or stretching forces.
Clinicians use the neck location of Erb’s Point for diagnostic purposes. Electrical stimulation applied here can elicit muscle contraction in the upper arm, assessing the health and conductivity of the C5 and C6 nerve roots. It also serves as a landmark for regional anesthesia, allowing for the targeted blocking of nerves supplying the neck and upper chest skin.
Clinical Significance of Brachial Plexus Injury
Injury to the neck location of Erb’s Point typically involves damage to the upper trunk of the brachial plexus, leading to Erb-Duchenne paralysis, or Erb’s Palsy. This injury affects the C5 and C6 nerve roots, which control many shoulder and elbow muscles. The resulting muscle weakness and loss of sensation can range from temporary numbness to complete paralysis of the shoulder and upper arm.
A common mechanism of injury is excessive stretching or sudden downward traction on the shoulder, pulling the nerve roots away from the spinal cord. In infants, this injury frequently occurs during difficult childbirth, especially in cases of shoulder dystocia. The force applied during delivery can overstretch the nerves at Erb’s Point. In adults, similar injuries result from severe falls or high-impact trauma that violently separates the head and shoulder.
The physical presentation of Erb’s Palsy is characteristic. The affected arm typically hangs limply by the side, internally rotated and adducted against the body. The forearm is often extended and pronated, leading to the classic “waiter’s tip” posture. Patients lose the ability to abduct the arm, externally rotate the shoulder, and flex the elbow, as these functions are controlled by muscles supplied by the damaged nerves (e.g., deltoid and biceps).
The severity depends on the nature of the nerve damage, which can involve simple stretching, scar tissue formation, or a complete tear from the spinal cord. Milder cases in infants often resolve spontaneously over several months. More severe injuries require intensive physical therapy and may necessitate surgical intervention. Early recognition of the injury location is important for guiding treatment and improving functional recovery.
The Cardiac Auscultation Landmark
The second meaning of Erb’s Point refers to a specific landmark on the anterior chest wall used for listening to heart sounds. This cardiac point is located on the left side of the sternum, precisely at the level of the third intercostal space. This places it one rib space below the location where the pulmonic valve sound is typically heard.
This location is often considered the “fifth point” of auscultation, alongside the four points corresponding to the aortic, pulmonic, tricuspid, and mitral valves. Erb’s Point is unique because it does not correspond directly to a single heart valve. Instead, it is a location where sounds originating from multiple valves are often equally audible. It is positioned near the center of the precordium, the region over the heart.
The primary function of auscultating at this point is to listen for the second heart sound (S2) and to detect subtle heart murmurs. The S2 sound is created by the simultaneous closure of the aortic and pulmonic valves. Murmurs resulting from the backflow of blood, such as aortic or pulmonary regurgitation, are often distinct and clearly heard here. Using a stethoscope’s diaphragm at this location provides diagnostic information about the function of the semilunar valves and overall cardiac health.