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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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Sulcus/gyrus and brain, lateral view
These two different terms must be analyzed together. The Latin term [sulcus] means "groove or fissure". Its plural form is [sulci]. There are many anatomical sulci in the body, one of them being the costal sulcus in the ribs.
The second term [gyrus] is also Latin and means "circle or ring", as used in the words gyroscope or gyrations. In its adjective or descriptive form, [gyrus] is used to denote something "bent, curved, or broad-shouldered"1. The plural form is [gyri]. In the case of the brain a gyrus is formed as a mound or an elevation between the "valleys" of the sulci (see image). If you click on the image a secondary image depicting the lateral aspect of the brain will appear.
In the brain there are many sulci, the secondary image shows the lateral or Sylvian sulcus, and the central sulcus or sulcus of Rolando.
In relation to the central sulcus there are two gyri. The anteriorly situated precentral gyrus is considered the primary motor cortex and associated with voluntary motor activity (colored in green in the secondary image). The postcentral gyrus (colored in blue) is situated posterior to the central sulcus and is the primary sensory cortex, associated with somatic (bodily) conscious sensation.
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
Initial image by:Albert Kok,courtesy of:Wikipedia.org. Second image modified from the original image by Henry Vandyke Carter, MD., courtesy of bartleby.com
Terms suggested by Sara Mueller.
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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.
Adam Christian Thebesius
Adam Christian Thebesius (1686- 1732). German physician and anatomist, Thebesius studied in the University of Leiden, Netherlands, where he received his doctorate in 1708 with the thesis "De circulo sanguinis in corde" (on the circulation of the blood in the heart). In 1713 he became a member of the Royal Academy of Natural Scientists (Kaiserliche Akademie der Naturforscher), where he adopted the Latin name "Eyryphon". Besides his natural sciences and medical research, Thebesius developed an interest in astrophysics.
Extremely interested in coronary circulation, Thebesius injected dyes and fluids in the coronary arteries, veins, and coronary sinus. Along with Raymond Vieussens (1635-1713) , Thebesius described all these structures. Today his name is attached to the eponymic Thebesian veins (venae cordi minima), and the Thebesian valve guarding the exit of the coronary sinus into the right atrium of the heart. Both these structures were mentioned in his 1708 doctoral thesis
Sources:
1. “The Role of the Thebesian Vessels in the Circulation of the Heart” Wearn, J.T. J Exp Med. 1928 January 31; 47(2): 293–315
2. The Story Behind the Word. Some Interesting Origins of Medical Terms. Wain,H. 1958.
3. The Origin of Medical Terms. Skinner, H.A. 1970
Original image in the public domain, courtesy of the National Library of Medicine
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The ventricular system of the brain is an interconnected system of cavities and ducts within the brain through which cerebrospinal fluid (CSF) circulates. The CSF is produced in the choroid plexuses located within the ventricles.
Ventricular system of the brain
Brain dissection - 4th ventricle
There are two large curved lateral ventricles, each found within a cerebral hemisphere. They connect with the third ventricle via an opening called the "foramen of Monro". The third ventricle connects with the fourth ventricle by way of a slender canal called the "cerebral aqueduct" or the "aqueduct of Sylvius".
The third ventricle is found deep within the brain between the right and left diencephalic portion of the cerebrum.
The fourth ventricle is located between the pons of the brain stem anteriorly and the cerebellum posteriorly. This ventricle has a rhomboidal shape and it connects with the external aspect of the brain and the subarachnoid space. Failure of this CSF drainage from the ventricles to the subarachnoid space can lead to pathological accumulation of CSF within the ventricles and hydrocephalus.
The line drawn image shows a lateral view of the brain with a superimposed image of the ventricular system. If you click on this image, you will see a superior view of a cast of the ventricular system (by Retzius).
The dissection image shows a posterior view of the brain stem and the cerebellum which has been opened in the median plane to expose the 4th ventricle. Click on the image to see a larger version.
Line images in the public domain by Henry VanDyke Carter, MD. (Gray's Anatomy) Dissection images property of CAA, Inc. Photographer E. Klein
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The cerebrospinal fluid (CSF) is a colorless, transparent fluid produced from the arterial flow of blood by the choroid plexuses found within the ventricular system of the brain. The CSF exits the ventricular system and enters the subarachnoid space and its cisterns. It is then absorbed at the level of the arachnoid granulations into the venous component of the cardiovascular system.
The CSF has many functions, some of them being protection, the creation of a fluid environment where the brain 'floats", cleansing, and others. For a more detailed description of the CSF, click here.
The CSF is produced at an average rate of 550-700ml/day. It is absorbed at the same rate. An imbalance between production and absorption of CSF (as well as a blockage within the ventricular system) can lead to an accumulation of CSF within the brain, causing hydrocephalus.
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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.
Hippocrates
Hippocrates of Cos (460 BC - 370 BC). A Greek physician, Hippocrates was born on the Greek island of Cos (Kos) c. 460BC. Considered the "Father of Medicine" he removed Medicine from the realms of superstition and magic. He was the first to record medical writings and is considered the first one to use and maintain proper medical terminology. There are many writing attributed to Hippocrates, but there is no assurance that these were actually written by Hippocrates himself. Hippocrates changed the art of medical diagnosis by replacing supernatural precepts with observation-based methodology. Natural, rather than supernatural causes, would from here on explain all disease processes, what was known as Rational Medicine.
He is known for having set the oath that governs medical principles, the Hippocratic Oath, although there are many authors that contend that this oath was written long time after he died.
Sources:
1. "Hippocrates himself" JAMA. 1968;204(12):1138-1139
2. "Hippocrates: father of medicine" Tan, S Y (01/01/2002). Singapore medical journal(0037-5675), 43(1), p.5.
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Anterior view of the thorax, showing surface
relations of bones, lungs (purple), pleura (blue),
and heart (red outline).
P. Pulmonary valve. A. Aortic valve.
B. Bicuspid valve. T. Tricuspid valve
This is a combined word arising from terms [atrium], [ventricle], and [sulcus]. For the etymology of each word, click on the corresponding link.
The atrioventricular sulcus, also know as the "coronary groove" or "coronary sulcus" is an evident incomplete groove between the atria and ventricles of the heart. It is complete posteriorly and is separated anterosuperiorly by the roots of the aorta and the pulmonary trunk. It contains the right coronary artery on the right side, and the circumflex artery on the left side, hence the name "coronary groove". These coronary arteries are not visible as they are usually covered by the epicardium and subepicardial fat.
The atrioventricular sulcus (and the corresponding coronaries) are also in relation to the deeper situated atrioventricular (AV) valves, the tricuspid valve on the right; and the mitral or bicuspid valve on the left side. The accompanying image depicts the location of the AV valves, and therefore the location of the AV sulcus. The image is an anterior view of the thorax, showing surface relations of bones, lungs (purple), pleura (blue), and heart (red outline). P. Pulmonary valve. A. Aortic valve. B. Bicuspid valve. T. Tricuspid valve
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 by Henry Vandyke Carter, MD., courtesy of bartleby.com