Medical Terminology Daily (MTD) is a blog sponsored by Clinical Anatomy Associates, Inc. as a service to the medical community, medical students, and the medical industry. We will post a workweek daily medical or surgical term, its 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

Antoine Louis

French surgeon, anatomist, and physiologist. Following his medical studies and a long career as a physiologist, Antoine Louis was named Permanent Secretary of the Royal French Academy of Surgery. His other titles were those of Professor of the Royal Academy, Consultant Surgeon of the Armies of the King, member of the Royal Society of Sciences of Montpellier, Inspector of the Royal Military Hospitals, and Doctor in Law of the University of Paris. As a member of these academies Louis was instrumental in the design and construction of the guillotine. Initially called the "Louisette", this device was later named after another French physician in the same committee, Dr. Joseph-Ignace Guillotin.

Antoine Louis' name is better know to history as the eponymic origin of the "sternal angle" also know as the "Angle of Louis" and synonymously (probably by misspelling or translation) the "angle of Lewis", and "angle of Ludwig". This anatomical landmark is extremely important as it serves as a superficial landmark for important anatomical occurrences (click here).

As a point of controversy, there are some that contest the history of this eponym adjudicating it to Pierre Charles Alexander Louis (1787-1872), another French physician dedicated to the study of tuberculosis.

1. Srickland, N; Strickland A Angle of Louis, More Than Meets the Eye. MedTalks:
2. Ramana, R. K., Sanagala, T. and Lichtenberg, R. (2006), A New Angle on the Angle of Louis. Congestive Heart Failure, 12: 197–199
. "The origin of Medical Terms" Skinner, HA; 1970

 "Clinical Anatomy Associates, Inc., and the contributors of "Medical Terminology Daily" wish to thank all individuals who donate their bodies and tissues for the advancement of education and research”.

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The anatomical laws of Miranda

Intended initially as a humorous view of anatomy, the "Anatomical Laws of Miranda" have a very serious objective. They support the fact that in every interventional case the operator should be extremely aware of the potential anatomical variations present. They also point to the fact that in real life, human anatomy does not look exactly like the anatomy books, models or prosections, and practice in the art of dissection and constant study are needed to ensure the proper identification of anatomical structures in surgery.

These laws are not original, they have been partially expressed at one time or another by several anatomists and surgeons, including Dr. Aaron Ruhalter and Dr. Robert Acland. What I have done is put them officially together and create the corollaries.

Efrain A. Miranda, Ph.D.
The anatomical laws of Miranda
  • 1. The only constant in anatomy is variation
  • 2. Nothing in the human body is really colored... or labeled
  • 3. No anatomical structure has the moral obligation to be where they are supposed to be

There are corollaries to these laws and visitors to this web site are invited to provide us with their thoughts and addenda to the anatomical laws.


1a. In the case of the so-called "anatomical constants"...law number 1 also applies

2.a. Black and white anatomy books are sometimes better to study than color atlases

2.b. Arteries are not red, nerves are not yellow, and lymphatic vessels are definitely not green!

2c. Nothing looks exactly like the anatomy books, computer simulations, or models. Food for thought for those medical schools that are eliminating dissection from their medical curricula.

3.a. This leads to that dreadful "Oooops!" sometimes heard in surgery

3.b. This also leads to the comment "It HAS to be around here!", which is dreadful if the "here" is a patient in surgery. 

3c. It is interesting that several medical schools are moving away from cadaver disection in first year medical school and using models or 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.

If you want to download a PowerPoint slide of the "Laws of Miranda" click here and follow the instructions of your browser.

A great resource to study on anatomical variations is the Illustrated Encyclopedia of Human Anatomic Variation, which was originally hosted by the University of Iowa. Today it resides at anatomyatlases.org, and the curator is Ronald A. Bergman, Ph.D.