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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Rectum

Published: Monday, June 24, 2013 07:00 | Written by: Efrain A. Miranda, Ph.D. | Hits: 6619

The rectum is the most distal segment of the large intestine. 

The word [rectum] arises from the Latin [rectus] and means "straight", such as its use in the name "rectus abdominis" for the "straight muscle of the abdomen".

It seems a misnomer, as the rectum of the human species is actually "S" shaped, as seen in the accompanying image. The reason for this discrepancy is that the rectum was named by Galen of Pergamon (129AD - 200 AD) who himself studied this structure in animals such as sheep and goats. In these animals the rectum is indeed straight, and since contradicting Galen was not acceptable (see Michael Servetus), the name has survived until this day. Even Andreas Vesalius has in his 1953 "Fabrica" a depiction of a straight rectum in the human! Click on the bar beneath the image to see Vesalius' image of the rectum.

The proximal end of the rectum is not clearly discernible from the sigmoidorectal region, from here the rectum has an "S" shape, measures approximately six to seven inches in length (15 - 17 cm), and it ends distally at the junction of the rectum with the  pelvic diaphragm. It is at this point that the anal canal begins.

 1. Sigmoid colon 2. Rectum 3. Anus 4. Inferior rectal valve 5. Middle rectal valve 6. Superior rectal valveLarge Intestine - Vesalius 1543
The rectum is characterized by three transverse rectal folds, one on the right side, and two on the left side. These folds are know as the "rectal valves" or the "valves of Houston". The middle rectal fold is known to European anatomists as the "valve of  Kohlrausch" Their function in maintaining fecal material in place as well as their function in defecation is still under study. The rectal valves also have a high level of anatomical variation and may not be present at all.

Image source: "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
Recommended reading: "Transverse Folds of Rectum: Anatomic Study and Clinical Implications" Shafik, A, et al. Clin Anat 14: 196-203 (2001).
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