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.

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

"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 image depicts a case of a coronary artery arising from the pulmonary trunk! 

Source:
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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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.

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.

This article is the second in a series of three; Click here for the first article. 
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"The only constant in anatomy is variation". 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.

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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