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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Torus - By LucasVB [Public domain], via Wikimedia Commons
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The word [torus] is of Latin origin and refers to “a rounded protuberance or swelling”. In science, it refers to a doughnut-shaped structure (see image). It also refers to the rounded, bulging, and circular base component of a pillar, found between the square plinth and the main body of the pillar. The torus can be seen in Egyptian, Greek, and Roman style pillars.

The term is used in anatomy and medicine to denote normal or abnormal circular or semicircular protuberances, as in the case of the “torus tubarius”, a normal semicircular elevation found at the ostium of the auditory tube (of Eustachius) in the lateral walls of the rhinopharynx. The torus tubarius elevation is due to the presence of lymphoid tissue which can get inflamed.

Torus mandibularis. An exostosis that develops on the inner side of the mandible
Torus palatinus: a benign, small exostosis that appears in the midline of the hard palate

In orthopedics it is used to denote a compression fracture where the cortex of a long bone close to one of its epiphyses buckles under longitudinal (axial) compression. The look of the fracture is similar to the location of the torus in a pillar. An example of this is the torus fracture (also known as buckle fractures) in children.

The term [torulus] is related to [torus], as it means a “small torus” and it refers to a small elevation, which is synonymous with the word “papilla”. An example of this is the term torulus tactiles palmaris, referring to small elevations on the palms of the hand. Another related term is [torulosis], referring to a large number of small elevations or pimples.

The following images are of a Greek pillar taken in 2014 in Athens showing the location of the torus. The next image shows a torus fracture. The image is from www.kidsfractures.com/forearm/ and we thank them for sharing the image with us. This is a great site for information on fractures in children.

Greek pillar - Personal picture Athens 2014
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Torus fracture - www.kidsfractures.com/forearm/
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Sources:
1. “Medical Meanings: A Glossary of Word Origins” Haubrich, WS. Am Coll Phys. Philadelphia 1997
2. “The Origin of Medical Terms” Skinner, HA 1970, New York. Hafner Publishing Company
3. “Taber’s Cyclopedic Medical Dictionary” 16th Ed. 1989. Philadelphia. FA Davis Company
4.  www.kidsfractures.com/forearm/

Torus image: By LucasVB [Public domain], via Wikimedia Commons

Thanks to Jackie Miranda-Klein for suggesting this post.  Dr. Miranda.