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.
Sir Arthur Keith
Sir Arthur Keith (1866–1955) was a Scottish physician, anatomist and anthropologist. He studied medicine at the University of Aberdeen, earning his Bachelor of Medicine in 1888. He traveled to Siam and worked for three years as a medical officed in a rubber plantation and mine. Upon his return to London, he continued his medical studies at University College. He became a fellow of the Royal College of Surgeons of England in 1894.
Keith held various academic positions, including demonstrator of anatomy at the London Hospital, where his initial anatomical research expanded to include pathological specimens associated with clinical cardiology. His collaboration with Sir James Mackenzie (1853 – 1925), a cardiologist studying cardiac arrhythmias using polygraph tracings (a device used to study cardiac arrythmias before the invention of the electrocardiograph by William Einthoven (1860 – 1927), piqued Keith’s interest in the anatomical basis of heart rhythm disorders.
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He was also an accomplished artist, and his anatomical illustrations and dissections helped clarify the structure and pathological variations of the atrioventricular conduction system. Through extensive dissection of post-mortem hearts sent by Mackenzie, Keith contributed to understanding the relationship between structural features of the conduction system and clinical manifestations of arrhythmias.
The discovery of the sinoatrial (SA) node is among Keith’s most enduring scientific legacies. Inspired by the 1906 work of Japanese anatomist Sunao Tawara, who described the atrioventricular node and conduction pathways in the mammalian heart, Keith and Martin W. Flack (a medical student at the time) extended this work in a search for the anatomical site responsible for initiating the heartbeat.
In 1906, while studying the heart of a mole, Flack identified a distinct structure at the junction of the superior vena cava and right atrium. Recognizing its histological resemblance to known conduction tissue, Keith and Flack named this structure the sino-auricular node. They hypothesized that this node was the dominant center initiating cardiac rhythm. Their work was published in 1907 in the Journal of Anatomy and Physiology. This publication completed the anatomical outline of the conduction system of the heart as we know it today.
Keith was appointed Conservator and Hunterian Professor at the Royal College of Surgeons in 1908 and transitioned his studies toward evolutionary anatomy and anthropology. He became an influential figure in paleoanthropology, published several books on human evolution, and served as President of the Royal Anthropological Institute and Rector of Aberdeen University. Knighted in 1921 and elected Fellow of the Royal Society in 1913, Keith remained active in research and writing until his death in 1955.
Sources:
1. Mohr PD. Illustrations of the heart by Arthur Keith: His work with James Mackenzie on the pathophysiology of the heart 1903–1908. J Med Biogr. 2021;30(3):193–201
2. Silverman ME, Hollman A. Discovery of the sinus node by Keith and Flack: on the centennial of their 1907 publication. Heart. 2007;93(10):1184–1187.
3. Keith A, Flack M. The Form and Nature of the Muscular Connections between the Primary Divisions of the Vertebrate Heart. J Anat Physiol. 1907 Apr;41(Pt 3):172-89. PMID: 17232727; PMCID: PMC1289112.
4. Keith A, Flack M. The form and nature of the muscular connections between the primary divisions of the vertebrate heart. J Anat Physiol 1907;41: 172–189.
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