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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.
Dr. Willem Einthoven
Dr. Willem Einthoven (1860 - 1927). Einthoven was Dutch, born on 1860 in the city of Semarang in the island of Java. His father was a physician working for the Dutch military. He started his medical studies at the University of Utrecht, Holland. Having developed an interest in ophthalmology and physiology, he developed his medicine doctorate thesis on stereoscopic color vision.
In 1885 Einthoven became a Professor of Physiology at the University of Leiden. Having seen a demonstration of Augustus Waller’s “electrogram” (a device that recorded minute deviations on a mercury column when electrically stimulated) in 1887, he improved it by creating the “string galvanometer”. In 1901 Einthoven published his first recordings of what he called “elektrokardiogramm” (EKG).
The initial device was bulky, heavy, and required the patient to sit with both arms and the left leg in separate buckets of salt water, but it did record the electrical activity of the heart (Click here for an image of one of the first electrocardiographs). Eventually the device was commercialized and history was made. It was Einthoven who used the letter P,Q,R,S, and T in electrocardiography.
In 1924, Willem Einthoven was awarded the Nobel Prize in Physiology.
Sources:
1. "Willem Einthoven (1860-1927): father of electrocardiography". Merritt, C. Tan. SY. Singapore Med J 53:(1) 17
2. "Willem Einthoven (1860-1927)" Davies, M; Hollman, A. Heart. 1997 October; 78(4): 324
3. "Willem Einthoven: The development of the human electrocardiogram" Cajavilcaa, C.,Varonb, J.Resuscitation 76:3 2008; 325–328
Original image courtesy of "Images from the History of Medicine" at www.nih.gov.
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Cerebelum
The word [vermis] is Latin and means "worm".
The vermis is the name given by Galen of Pergamon (129AD - 200AD) to the median lobe of the cerebellum, since when seen from the superior aspect, this cerebellar lobe looks like a multisegmented worm. See accompanying image, or click for a larger depiction.
When seen in a median section, the cerebellar vermis looks like a multilobulated leaf with the fourth ventricle of the brain at its base. It is composed of several smaller lobules: Lingula, central, culmen, clivus, tuber vermis, pyramid, uvula, and nodular lobes.
Median section image link courtesy of UCLA Radiology
Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia
3 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
4. "Anatomy of the Human Body" Henry Gray 1918. Philadelphia: Lea & Febiger
Image modified by CAA, Inc. Original image courtesy of bartleby.com
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"Nothing in the human body is colored, or labeled"
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"The Chirurgeon must knowe the Anatomie". Thus states Thomas Vicary (1460 -1561) on the knowledge of Anatomy. He continues: "...for all authors write against those surgeons who work in a man's body not knowing the Anatomie"1. There is no doubt that knowledge must include the awareness of the possibility of anatomical variations. Some anatomical variations, like the "Corona Mortis" can be critical, and in some surgical cases, be the cause for exsanguination!
It is interesting that several medical schools are reducing the total number of hours working on, or moving away from cadaver disection in first year medical school and using computer simulations instead. No computer simulation will give the medical student the detail, variations, and feel of the tissues as actual hands-on experience. I am sure no one wants a surgeon whose first view of the internal aspect of a human body is a living patient...on the surgical table.
It is a fact that "Nothing in the human body is really colored... or labeled" or as someone else said "nothing looks exactly like the anatomy book", unless it is photography, and then each photo is taken after hours of laboring to "Netterize" the organ or area that one is trying to detail. Nothing gives the future professional the exact idea of what to expect in the future patient than the hours and hours of laborious work in the anatomy laboratory.
The same is true with anatomical variations, one "standard" digital cadaver,even with built-in anatomical variations does not give the student the sense of awe and discovery when an anatomical variation is found, interpreted, and analyzed with a group of peers, contributing to the learning process and the formation of future health care professionals.When questioning what is normal or abnormal, Dr. Elizabeth Murray says it most elegantly: "The cadaver is always right"
The image depicts a case of a coronary artery arising from the pulmonary trunk!
Sources:
1. "The Chirurgeon must knowe the Anatomie" R. Shane Tubbs Clin Anat 26:417 (2013)
2. "Two cases of an abnormal coronary artery of the heart arising from the pulmonary artery"Brooks, H; J. Anat. Physiol. 20:26-29, 1886 (anatomyatlases.org)
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"No anatomical structure has the moral obligation to be where they are supposed to be"
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Not only may an anatomical structure be absent, such as in the case of renal aplasia or agenesis, or in the case of a non-existent circumflex coronary artery, but sometimes extra structures can be found. Such is the case where a kidney can present two or even three ureters, all functional. Double inferior vena cavae, cervical ribs, lumbar ribs, the list goes on and on!
Muscles can be added to this list, again, with absence of a muscle, or with new and completely unexpected attachments. An example of this is the presence of a continuation of the rectus abdominis muscle into the chest region, a variation called a sternalis muscle.
The accompanying image shows the sternalis muscle in one of the "muscle plates" of De Humani Corporis Fabrica Libri Septem, published in 1543 by Andreas Vesalius. This image was criticized by showing a muscle that does not exist, although Vesalius clearly stated in the text of his book that this was an anatomical variation that he had seen.
For many decades surgeons had to operate and "see what they could find". There were the days of the exploratory laparotomy. After the discovery of the application of X-rays by Wilhem Konrad Roentgen (1845 - 1923) and the incredible advances in imaging techniques including CT-scan, MRI, PET, etc, the surgeon is now not usually surprised by anatomical variations.
There are areas in the body that have an high rate of anatomical variation, such as the hepatobiliary region, which includes the "Triangle of Calot". In this area, the standard anatomy is found only in 64% of the cases! In the rest, expect the unexpected. Lahey (1948) states "...the fact that cholecystectomy is a dangerous operation. It is dangerous unless one realizes.... that anomalous anatomy is very common". Today the dangers are less, because of better visualization and technology, but anatomical variations are still there.
Another area where anatomical variations are extremely important is the heart's coronary circulation. Anatomical variations can cause different cardiac dominance. Normal anatomy states that there are two coronary arteries, yet, up to five separate coronary arteries arising directly from the ascending aorta have been described! There is one variation where the left coronary arises from the right coronary artery, effectively having only one artery arise from the aorta and being in charge of all the arterial supply to the heart. What happens if this single artery stenoses? Bear in mind that this is not an "anomalous" vessel, it is just an anatomical variation.
Sources:
1. Lahey DH, discussing the paper "Partial Hepatectomy with Intrahepatic Cholangiojejunostomy" by Wilson H, and Gillespie CE, Ann Surg. 1949 June; 129(6): 756–765
2. "Renal aplasia is the predominant cause of congenital solitary kidneys" Hiraoka, M et al Kidney Int. 2002 May;61(5):1840-4.
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"The only constant in anatomy is variation"
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This dictum is incredibly powerful and true. Even the so-called "anatomical constants" are subject to it.
One common misconception is that "we are all the same". This could not be further from the truth. Every body is different from every else's body. Anatomical variations range from the minimal to the incredible. One of the most interesting anatomical variations is the one called "situs inversus". In this case the individual is a mirror image of a human. The apex of the heart points to the right side of the body; the duodenum circles to the right, the liver "hangs" from the left side of the respiratory diaphragm, etc. This particular anatomical variation presents in different degrees and can sometimes coexist with some cardiovascular congenital abnormalities.
Of course there are minor anatomical variations that have no effect on daily life at all and are only discovered by accident, or upon autopsy or dissection. One of the most complete resources on this topic is the Illustrated Encyclopedia of Human Anatomic Variations. An excerpt from this site states: "It is clear that textbook writers and teachers over the centuries, even until today, fail to understand or to transmit to their students the crucial concept that anatomical and physiological diversity and variation is a canon of living organisms. This failure leads to the belief that textbooks are conveying immutable facts with only few anomalous exceptions".
Shown here is an extremely rare case of a third kidney. Dixon (1911) describes in his research paper that as of that date, only 10 cases were known, of these only eight were recorded, with 87% of them found on the left side of the body. Click on the image for a larger depiction.
Source and primary image: "Supernumerary kidney: The occurrence of three kidneys in an adult male subject" Dixon, A.F. J. Anat. Physiol. 45:117-121, 1911.
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The prefix [para-] has a Greek origin and means "beside" or "alongside". Today we add the meaning of "parallel to".
We see the daily application of this prefix in words such as [paramedic], [parajournalism], [paralogism], and [paranormal]. Medical applications of the term include:
- parasternal: alongside the sternum, such as the internal thoracic vessels
- paramedian: alongside the median plane
- parasagittal: parallel to a sagittal plane (synonym with paramedian)
- paraumbilical: alongside the umbilicus, such as paraumbilical visceral extrusion in a gastroschisis
- parathyroid glands: glands that are found besides the thyroid gland, etc.