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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Sulcus / gyrus

Sulcus / gyrus and Brain, lateral view (www.bartleby.com)
Sulcus/gyrus and brain, lateral view


These two different terms must be analyzed together. The Latin term [sulcus] means "groove or fissure". Its plural form is [sulci]. There are many anatomical sulci in the body, one of them being the costal sulcus in the ribs.

The second term [gyrus] is also Latin and means "circle or ring", as used in the words gyroscope or gyrations. In its adjective or descriptive form, [gyrus] is used to denote something "bent, curved, or broad-shouldered"1. The plural form is [gyri]. In the case of the brain a gyrus is formed as a mound or an elevation between the "valleys" of the sulci (see image). If you click on the image a secondary image depicting the lateral aspect of the brain will appear.

In the brain there are many sulci, the secondary image shows the lateral or Sylvian sulcus, and the central sulcus or sulcus of Rolando.

In relation to the central sulcus there are two gyri. The anteriorly situated precentral gyrus is considered the primary motor cortex and associated with voluntary motor activity (colored in green in the secondary image).  The postcentral gyrus (colored in blue) is situated posterior to the central sulcus and is the primary sensory cortex, associated with somatic (bodily) conscious sensation.

Sources:
1. "The Origin of Medical Terms" Skinner, HA 1970 Hafner Publishing Co.
2. "Medical Meanings - A Glossary of Word Origins" Haubrich, WD. ACP Philadelphia
3 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
4. "Anatomy of the Human Body" Henry Gray 1918. Philadelphia: Lea & Febiger
Initial image by:Albert Kok,courtesy of:Wikipedia.org. Second image modified from the original image by Henry Vandyke Carter, MD., courtesy of bartleby.com
Terms suggested by Sara Mueller.