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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Rib

Thoracic rib, Posteroinferior view
Thoracic rib, Posteroinferior view


The ribs form the lateral bony wall of the thorax.  The ribs are paired and there are 12 pairs of ribs in the human thorax, most of them connecting the thoracic spine with the sternum. They are numbered from superior to inferior.

Ribs have different anatomical characteristics depending on their level. A typical rib has the following characteristics from posterior to anterior:

• Head: The head of each rib articulates with one or two ribs depending on their level. Typically ribs number 1,2, 10, 11, and 12 articulate with one vertebra, while the rest articulate with two vertebrae.

Facets: These are the articular surfaces found in the head of each rib. They are covered by hyaline cartilage and form part of the costovertebral synovial joints. In the case of ribs 3 to 9, since they articulate with two vertebrae, they have two facets, each one called a demifacet, with an interarticular crest between them.

• Neck: A short, somewhat narrower portion of the rib that projects straight posterolaterally.

• Costal tubercle: A bony protuberance, usually with two components, one articular and one non-articular. The articular part of the costal tubercle presents with a facet that articulates with the transverse process of a thoracic vertebra.

• Costal angle: A sharp posterior curvature of the rib. The body when supine rests of these costal angles which deflect pressure from the thoracic spine.

• Costal body: The area of the rib anterior to the costal angle. In most ribs this oval-shaped region of the rib presents with an inferior and internal groove. This is the costal groove or costal sulcus. The corresponding level intercostal artery, vein, and nerve are found in the costal sulcus.

• Costal cartilage: All ribs have an anterior fibrocartilaginous component. Some of them attach directly to the sternum (chondrosternal joints), while some of them attach only to other costal cartilages (chondrochondral joints).

The 12 pairs of ribs are divided as follows:

• True ribs: Ribs 1-7, which attach by way of their costal cartilage directly to the sternum

• False ribs: Ribs 8-10, whose costal cartilage attach only to the cartilage of the superior rib, creating a lower border for the thoracic cage known as the costal margin.

• Free or "floating" ribs: Ribs 11 and 12. Their anterior cartilaginous end does not attach to sternum or other cartilage, so the end is free. The term "floating" although used, is a misnomer as these ribs do attach posteriorly to the thoracic spine.

There can be anatomical variations to the ribs, including the existence of extra cervical or lumbar ribs.

Sources:
1 "Tratado de Anatomia Humana" Testut et Latarjet 8 Ed. 1931 Salvat Editores, Spain
2. "Anatomy of the Human Body" Henry Gray 1918. Philadelphia: Lea & Febiger
Original image courtesy of bartleby.com. For more information: click here