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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Collateral circulation

The term "collateral circulation" is generally used to denote a situation where small blood channels dilate and provide blood supply when a pathology creates a stricture and diminishes blood flow (ischemia).

Although the above is correct, the term is also applicable to a normal, non-pathological situation most common in the human body. Please refer to the accompanying image for the following explanation. If needed, click on the image for a larger depiction. In the image, the arrows represent direction of flow.

Most organs or organ segments receive blood supply from more than one source of blood supply. In some cases, like the stomach, there are up to four arteries that provide blood supply to the organ: the right and left gastric arteries, and the right and left gastroepiploic arteries.

Collateral circulation. The arrows indicate direction of arterial blood flow. The dashed lines delimitate vascular territoriesImages property of:CAA.Inc. Artist: Dr. E. Miranda
In other cases, like the small intestine shown in the image, blood arrives to the organ arising from several arteries (A, B, and C) that themselves arise from a parent structure. Because of hydrodynamics, the vascular territories of each artery (represented by dashed lines) tend not to overlap. If for any reason there is stenosisor blockage in any of these arteries (A,B, or C) blood will flow immediately through an alternate route and the organ will not suffer ischemia or necrosis

This is extremely important, as these collateral channels maintain blood supply to areas that may be affected by bending, such as the elbow and knee, which have a rich collateral network. Most of the organs in the body, with some exceptions (brain, heart), have collateral circulation.

Collateral circulation is extremely important for surgery, as surgeons can safely remove parts of organs without affecting the blood supply to the organ. This is also true for all gastrointestinal anastomoses.

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