Medical Terminology Daily - Est. 2012

Medical Terminology Daily (MTD) is a blog sponsored by Clinical Anatomy Associates, Inc. as a service to the medical community. We post anatomical, medical or surgical terms, their meaning and usage, as well as biographical notes on anatomists, surgeons, and researchers through the ages. Be warned that some of the images used depict human anatomical specimens.

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A Moment in History

Jean George Bachman

Jean George Bachmann
(1877 – 1959)

French physician–physiologist whose experimental work in the early twentieth century provided the first clear functional description of a preferential interatrial conduction pathway. This structure, eponymically named “Bachmann’s bundle”, plays a central role in normal atrial activation and in the pathophysiology of interatrial block and atrial arrhythmias.

As a young man, Bachmann served as a merchant sailor, crossing the Atlantic multiple times. He emigrated to the United States in 1902 and earned his medical degree at the top of his class from Jefferson Medical College in Philadelphia in 1907. He stayed at this Medical College as a demonstrator and physiologist. In 1910, he joined Emory University in Atlanta. Between 1917 -1918 he served as a medical officer in the US Army. He retired from Emory in 1947 and continued his private medical practice until his death in 1959.

On the personal side, Bachmann was a man of many talents: a polyglot, he was fluent in German, French, Spanish and English. He was a chef in his own right and occasionally worked as a chef in international hotels. In fact, he paid his tuition at Jefferson Medical College, working both as a chef and as a language tutor.

The intrinsic cardiac conduction system was a major focus of cardiovascular research in the late nineteenth and early twentieth centuries. The atrioventricular (AV) node was discovered and described by Sunao Tawara and Karl Albert Aschoff in 1906, and the sinoatrial node by Arthur Keith and Martin Flack in 1907.

While the connections that distribute the electrical impulse from the AV node to the ventricles were known through the works of Wilhelm His Jr, in 1893 and Jan Evangelista Purkinje in 1839, the mechanism by which electrical impulses spread between the atria remained uncertain.

In 1916 Bachmann published a paper titled “The Inter-Auricular Time Interval” in the American Journal of Physiology. Bachmann measured activation times between the right and left atria and demonstrated that interruption of a distinct anterior interatrial muscular band resulted in delayed left atrial activation. He concluded that this band constituted the principal route for rapid interatrial conduction.

Subsequent anatomical and electrophysiological studies confirmed the importance of the structure described by Bachmann, which came to bear his name. Bachmann’s bundle is now recognized as a key determinant of atrial activation patterns, and its dysfunction is associated with interatrial block, atrial fibrillation, and abnormal P-wave morphology. His work remains foundational in both basic cardiac anatomy and clinical electrophysiology.

Sources and references
1. Bachmann G. “The inter-auricular time interval”. Am J Physiol. 1916;41:309–320.
2. Hurst JW. “Profiles in Cardiology: Jean George Bachmann (1877–1959)”. Clin Cardiol. 1987;10:185–187.
3. Lemery R, Guiraudon G, Veinot JP. “Anatomic description of Bachmann’s bundle and its relation to the atrial septum”. Am J Cardiol. 2003;91:148–152.
4. "Remembering the canonical discoverers of the core components of the mammalian cardiac conduction system: Keith and Flack, Aschoff and Tawara, His, and Purkinje" Icilio Cavero and Henry Holzgrefe Advances in Physiology Education 2022 46:4, 549-579.
5. Knol WG, de Vos CB, Crijns HJGM, et al. “The Bachmann bundle and interatrial conduction” Heart Rhythm. 2019;16:127–133.
6. “Iatrogenic biatrial flutter. The role of the Bachmann’s bundle” Constán E.; García F., Linde, A.. Complejo Hospitalario de Jaén, Jaén. Spain
7. Keith A, Flack M. The form and nature of the muscular connections between the primary divisions of the vertebrate heart. J Anat Physiol 41: 172–189, 1907.


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This article is part of the series "A Moment in History" where we honor those who have contributed to the growth of medical knowledge in the areas of anatomy, medicine, surgery, and medical research.

Ether Dome Skylight
Ether Dome Skylight

During one of many trips this year, I found myself with a free day in Boston, Massachusetts. Had a recommendation to try and visit the Ether Dome, which I did, and it was an interesting, although short, experience.

The Ether Dome is the name given by the Massachusetts General Hospital (MGH) to the first operating room of the MGH and it is located under the dome at the top of the Bullfinch Building, named after its architect Charles Bullfinch (who later became one of the architects for the USA Capitol). The reason for the location of the operating room is that there is a large skylight that provided the light for the operations.

The operating room was in service between 1821 and 1867 and over 8,000 operations were performed here. It was later used as a storage are, a nurse’s dormitory, a dining room, and today as a teaching auditorium. It still has the arrangement of a semicircular staired pavilion, as in the early days of the operating room. The Ether Dome was designated a National Historic Site in 1965.

National Historic Site 1965

The reason for the name Ether Dome is that in this location, on October 16, 1846, anesthesia was used successfully for the first time. The surgeon was John C. Warren, one of the MGH’s founders. The anesthesiologist was William T. G. Morton, a dentist. The patient was Gilbert Abbott. The operation was the excision of a neck tumor. Upon waking up, the patient said that he had felt no pain.

Ether Dome Auditorium


This event was so revolutionary that painting and images have bee created all over to remember the occasion. One of most creative was the work done for a mural called “Ether Day, 1846” The artists were Warren and Lucia Prosperi, who in 2000-2001 took photographs of surgeons and administrators at MGH in period clothing in different poses to recreate the event of the first use of anesthesia. An oil painting of the mural can be seen at the Ether Dome.  If you are interested in visiting the MGH, I recommend planning your visit with the Paul S. Russel Museum of Medical History and Innovation. The museum itself is worth visiting. If you want, the Russel Museum has a virtual tour of the Ether Dome and the Hospital, click here.

Painting of the operation by Warren and Lucia Prosperi

Since the Ether Dome is an active teaching auditorium, it is not always available for visitors, to it is good to call ahead, I did not, and was lucky to enter the auditorium prior to a welcome meeting for first year medical students. What an historical location to begin your medical career!

The Ether Dome houses a plaster cast of a Roman statue, the Apollo Belvedere, an Egyptian mummy, and an old human skeleton used for teaching. 

Human skeleton at the Ether Dome

The Apollo Belvedere at the Ether Dome

 A large plaque on the wall reads: ” On October 16, 1846 in this room, then the operating theatre of the Hospital, was given the first public demonstration of Anæsthesia to the extent of producing insensibility to pain during a serious surgical operation. Sulphuric ether was administered by William Thomas Green Morton, a Boston dentist. The patient was Gilbert Abbott. The operation was the removal of a tumor under the jaw. The surgeon was John Collins Warren. 
The patient declared that he had felt no pain during the operation and was discharged well, December 7. Knowledge of this discovery spread from this room throughout the civilized world and a new era for surgery began.”

Ether Dome Plaque


Here is a photograph of a later operation in 1847 where Morton and Warren can be seen.

Warren and Morton, c.1847


I have written several articles about this topic, the event, and its protagonists. Here are some of the links:

 Note: Ether Dome Skylight image. Ravi Poorun [oddityinabox] CC BY-SA 3.0, via Wikimedia Commons. Public Domain