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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Subscapular muscle (subscapularis)

The subscapular muscle or subscapularis is a large triangular muscle which is found on the anterior aspect of the scapula, in close relation to the posterolateral aspect of the thorax. It is covered by a well-defined fascia layer, the subscapularis fascia. It is one of the muscles that forms the rotator cuff.

It originates from the internal aspect of the medial border of the scapula, in close proximity to the insertion of the serratus anterior (magnus), and the internal aspect of the inferolateral border of the scapula, where it is separated from the teres major muscle by a thick aponeurosis. It also takes origin directly from the subscapular fossa, where some of the muscular fibers attach directly to the bone.

The muscle inserts by way of a tendon in the lesser tubercle of the humerus and the anterior aspect of the glenohumeral joint capsule. The tendon of the muscle is separated from the neck of the scapula by a large bursa (the infratendinous bursa of the subscapularis) which communicates with the cavity of the glenohumeral joint through an aperture in the capsule.

It receives innervation by two subscapular nerves, both branches of the brachial plexus.

Subscapularis muscle - Image modified from the original by Henry VanDyke Carter, MD. Public domain
Subscapularis muscle.
Click on the image for a larger depiction 
The superior suprascapular nerve arises from the ventral rami of C5 and C6 nerve fibers. It branches from the posterior cord of the brachial plexus and supplies the superior aspect of the muscle. The inferior subscapular nerve arises from the ventral rami of C5 and C6 nerve fibers. It branches from the posterior cord of the brachial plexus and supplies the superior aspect of the muscle. Although these nerves have the same origin from the cervical spine, their origin from the posterior cord of the brachial plexus is different.

This muscle rotates the head of the humerus medially. When the upper extremity is raised, it draws the humerus anteroinferiorly.  As part of the shoulder’s rotator cuff it helps prevent subluxation of the glenohumeral joint by keeping the head of the humerus in situ.

The subscapularis is one of the 17 muscles that attach to the scapula.

Note: The image shown in this article is from “Gray’s Anatomy” (1918) which is in the public domain

Sources:
1. “Gray’s Anatomy” Henry Gray, 1918
2. "Tratado de Anatomia Humana" Testut et Latarjet 8th Ed. 1931 Salvat Editores, Spain
3. "Gray's Anatomy" 38th British Ed. Churchill Livingstone 1995
4. “An Illustrated Atlas of the Skeletal Muscles” Bowden, B. 4th Ed. Morton Publishing. 2015

Image modified from the original by Henry VanDyke Carter, MD. Public domain

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