Where is Erb's point located?

Erb's Point Location

Erb's point is located in the third intercostal space close to the sternum and serves as the fifth point of auscultation for heart examination. 1

Historical Background

Erb's point has historically been attributed to the German neurologist Wilhelm Heinrich Erb (1840-1921), and this attribution has now been confirmed through historical evidence. An American physician who attended Erb's lectures in Heidelberg reported that Erb explicitly introduced this "fifth point" of cardiac auscultation in his case presentations in the late 1890s 1. This is particularly notable because Erb, while known primarily for his neurological work, was actually chair of general medicine at the time.

It's important to note that there is another anatomical landmark also called "Erb's point" which is located in a completely different area - at the supraclavicular region. This has led to confusion in medical literature.

Anatomical Clarification

There are actually two distinct anatomical points named after Wilhelm Erb:

1. Cardiac Erb's Point: Located in the third intercostal space close to the sternum, used for cardiac auscultation 1.

2. Supraclavicular Erb's Point: Located just superior to the clavicle, used by Erb to transcutaneously elicit contractions of various proximal arm muscles with electrical stimulation 2.

The confusion between these two points has been documented in medical literature, with many mistakenly interchanging the terms "Erb's point" and "nerve point" when describing the point of emergence of the cutaneous branches of the cervical plexus near the posterior border of the sternocleidomastoid muscle 2.

Clinical Significance

Cardiac Erb's Point

• Serves as the fifth point of auscultation for heart examination
• Particularly useful for detecting murmurs of aortic incompetence, which may be best heard at this location 1
• Historically associated with auscultation of heart murmurs related to syphilitic aortitis

Supraclavicular Erb's Point

• Used in neurological examinations and electrophysiological studies
• Serves as a standard peripheral recording site when recording upper-extremity somatosensory evoked potentials (SSEPs) 3
• Can be used as a landmark to identify the spinal accessory nerve during neck dissection 4

Alternative Recording Sites

When the supraclavicular Erb's point is inaccessible during surgical procedures (either part of the surgical field or distorted by patient size or trauma), the axillary fossa can serve as an alternate peripheral recording site for somatosensory evoked potentials. The axillary response produces a waveform similar in morphology to that of the Erb's point response but occurs approximately 2.5 ms earlier 3.

Clinical Applications

In neurophysiological testing, Erb's point is used to record the N9 component of somatosensory evoked potentials, which is important for calculating conduction times in the somatosensory pathway 5. The N9-N14 conduction time reflects impulse propagation in the proximal part of the brachial plexus, cervical roots, and dorsal column, while the N14-N20 conduction time represents central conduction between the dorsal column nuclei and the cortex.

Understanding the precise location and significance of both Erb's points is crucial for accurate clinical examination, neurophysiological testing, and surgical procedures in the respective anatomical regions.