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-Louis Petit

Jean Louis Petit
(1674 – 1750)

French surgeon and anatomist, Jean Louis Petit was born in Paris in on March 13, 1674.  His family rented an apartment at his house to Alexis Littre (1658 – 1726), a French anatomist. Petit became an apprentice of Littre at seven years of age, helping him in the dissections for his lectures and at an early age became the assistant in charge of the anatomic amphitheater.

Because of Petit’s dedication to anatomy and medicine, in 1690 at the age of sixteen, became a disciple of a famous Paris surgeon, Castel.

In 1692, Petit entered the French army and performed surgery in two military campaigns. By 1693 he started delivering lectures and was accepted as a great surgeon, being invited to the most difficult operations.  In 1700 he was appointed Chief Surgeon of the Military School in Paris and in the same year he received the degree of Master of Surgery from the Faculty of Paris.

In 1715 he was made a member of the Royal Academy of Sciences and an honorary member of the Royal Society of London. He was appointed by the King as the first Director General of the Royal Academy of Surgery when it was founded in 1731.

Petit’s written works are of historical importance.  “Traite des Maladies des Os” ( A Treatise on Bone Diseases);  “Traite des Maladies Chirurgicales et des Operation” (A Treatise on Surgical Diseases and their Operations” This last book was published posthumously in 1774. He also published a monograph on hemorrhage, another on lachrymal fistula, and others.

He was one of the first to perform choIecystotomy and mastoidotomy. His original tourniquet design for amputations saved many in the battlefield and the design of the same surgical instrument today has not changed much since its invention by him.

His name is remembered in the lumbar triangle, also called the "triangle of Petit", and the abdominal hernia that can ensue through that area of weakness, the lumbar hernia or "Petit's hernia".

Sources:
1. “Jean Louis Petit – A Sketch of his Life, Character, and Writings” Hayne, AP San Fran Western Lancet 1875 4: 446-454
2. “Oeuvres compl?tes de Jean-Louis Petit” 1837 Imprimerie de F. Chapoulaud
3. Extraits de l'eloge de Jean-Louis Petit Ius dans Ia seance publique de I' Academie royale de chirurgie du 26 mai 1750” Louis A. Chirurgie 2001: 126 : 475- 81


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Artery

UPDATED: The term [artery] evolved from two Greek words. The first one is [αέρα], meaning "air", and the second one is [terein], a verb meaning "to keep" or "to maintain"1. [Artery] therefore means "to maintain or to keep air", which is furthest from what we know today! The reason is that initial observations on these structures happened in bodies after combat, or gladiators who had exsanguinated because of their wounds. The arteries were empty (full of air) or contained a mix of blood and air. Arteries were considered a type of windipe. In fact, the original anatomical term for trachea was that of [tracheartery], which means "the rough artery". We have learned since then the true function of the arteries, so the name was shortened to "trachea".

The modern definition of an artery is "a structure that takes blood away from the heart". The amount of oxygen within the vessel has no bearing on the definition; there are arteries that carry oxygenated blood and arteries that carry deoxygenated blood.

 The structure of an arterial wall. Courtesy Blausen.com

Histologically, an artery is composed of three layers. The external layer is called the "adventitia" or "tunica externa". It is composed mostly of connective tissue. The middle layer is called the "tunica media" and is composed by a varying number of elastic fibers and smooth muscle fibers arranged as shown in the image. The inner layer is called the "tunica intima". The inner portion of the tunica intima is called the endothelium.

Arteries that are closer to the heart have more elastic fibers in their tunica media. As we move further away from the heart arteries become smaller and increase the number of smooth muscle fibers. This is what histologists describe "elastic arteries" and "muscular arteries". The smallest muscular arteries are called "arterioles". Large arteries have their own blood supply, called the "vasa vasorum".

Sources:
1.
"The ancient Hellenic and Hippocratic origins of head and brain terminology" Panourias IG, Stranjalis G, Stavrinou L, Sakas DE. Clin Anat 2012 Jul;25(5):548-581
2. Image: "Blausen Gallery 2014" 
- Wikiversity Journal of Medicine. DOI:10.15347/wjm/2014.010. ISSN 20018762. Licensed under Creative Commons Attribution 3.0 via Wikimedia Commons - Original image

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