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.

Friedrich Gustav Jakob Henle
Friedrich Gustav Jakob Henle

Friedrich Gustav Jakob Henle (1809 -1885) German physician, anatomist, histologist, and physiologist. Born in  the city F?rth, Henle entered the University of Bonn and studied anatomy with Johannes Muller (1801 – 1859), a professor of anatomy and histology. Henle dedicated his efforts to scientific research, and became the managing editor of the journal “Archives of Anatomy, Physiology, and Scientific Medicine” founded by Muller.

Henle’s career in Berlin suffered after he was arrested for 40 days in jail, because of his past membership in a radical liberal and nationalistic student fraternity, the Burschenschaften. He transferred from Berlin to Zürich where he founded the School of Rational Medicine.

Among his publications, the “Allgemeine Anatomie “(1841) is considered the first treatise on microscopic histology. Also, his book “Handbuch der systematischen Anatomie des Menschen” (Handbook of Human Systematic Anatomy) is a great anatomy book with good illustrations.

Henle moved from Zürich to Heidelberg, and from there to Gôttingen, where he accepted the position of Professor of Anatomy. He stayed at Gôttingen until his death in 1885.

Henle’s many remembered contributions are mostly in the area of histology. His name is found in many eponyms. The eponym most associated with his name is “Henle’s loop”, part of the tubular component of a nephron.

  • Crypts of Henle: Microscopic pockets located in the conjunctiva of the eye
  • Henle's fissure: Fibrous tissue between the cardiac muscle fibers.
  • Henle's ampulla: Ampulla of the uterine (Fallopian) tube
  • Henle's layer: Outer layer of cells of root sheath of a hair follicle.
  • Henle's ligament (tendon): Tendon of the transversus abdominis muscle.
  • Henle's membrane: The layer forming the inner boundary of the choroid of the eye

Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. “The Man Behind the Eponym Jacob Henle: Henle’s Layer of the Internal Root Sheath” Steffen C. Am J Dermatopath (2001) 23(6): 549–551
3. “The life of Jacob Henle” Robinson A Medical Life Co. 1921.
Original image in the public domain. Courtesy of Wikipedia.