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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Trachea

Tracheobronchial tree. Modified from Gray's Anatomy
Tracheobronchial tree

The trachea, vernacularly known as the "windpipe",  is in the adult a 4 inch (10.1 cm) membranous tube which contains incomplete, almost circular rings of cartilage. Some authors describe between fourteen to sixteen of these incomplete rings of cartilage in the trachea.

These semicircular rings are open-ended posteriorly, where the trachea only has a membrane, thus being flattened posteriorly. This posterior aspect of the trachea is in close anatomical relationship with the thoracic esophagus.

The trachea begins at the inferior end of the larynx, just about the level of the sixth cervical vertebra, and descends in the superior mediastinum to the level of the sternal angle (of Louis) close to the superior border of the fifth thoracic vertebra, where it divides into two main bronchi, each entering the ipsilateral lung at the level of the pulmonary hilum.

The word [trachea] arises from the Greek [trakhus] meaning "rough". This is because in the original description of this structure there was the belief that all arteries were full of air (Lat. air = ar/aria). The trachea, being rough was called the "rough artery" or "tracheartery", which was later amended, eliminating the "artery" part. In Latin the term used for the trachea was [arteria aspera], also meaning "rough artery".

The internal lower border of the bifurcation of the trachea into the left and right main bronchi is knows as the carina, where the carinal lymphatic nodes are found.

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
Image modified by CAA, Inc. Original image courtesy of bartleby.com


Descending (thoracic) aorta

Posterior view of the contents of the thoracic cavity. The descending aorta is highlighted in red
Posterior view of the contents of the thoracic cavity.
The descending aorta is highlighted in red.

The descending aorta, also known as the thoracic aorta is the third portion of the aorta. It is found distal to the aortic arch in the posterior portion of the inferior mediastinum, and proximal to the abdominal aorta.

The descending aorta is situated between the lungs and has a close relation with the thoracic esophagus and the thoracic duct.

The descending aorta gives off 10 pairs of posterior intercostal arteries. The first intercostal artery, known as the supreme intercostal artery arises as a branch of the costocervical trunk of the subclavian artery. The last pair of arteries to arise from the descending aorta are the subcostal arteries, which pass under the 12th rib. The descending aorta also gives a number of smaller branches to the esophagus and the main stem bronchi.

The descending aorta ends at the aortic hiatus, where it continues as the abdominal aorta.

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
Image modified by CAA, Inc. Original image courtesy of bartleby.com


Etiology

First used by Galen of Pergamon (129AD - 200AD) the word [etiology] is of Greek origin. [α?τία] or [aitia], meaning "cause", and [λογία] or [-ology], meaning "study of". Etiology is the "study of cause". In medicine this word I used to denote the study of the causes for a pathology, disease, or condition.

Because of its Greek origin, Skinner (1970) states that the proper way of spelling this term should be ?tiology, but the initial "a" has been discarded through use.

There are many pathologies of unknown origin. In this case the word to use would be [idiopathic] or [idiopathy] meaning "of unknown cause"

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-cele

The suffix [-(o)cele] arises from the Greek [k?l?] meaning "dilation" or "pouching". In medical terminology this suffix is used to mean "hernia", "bulging", or a "dilation". In older times a synonym was used for hernia: "rupture".  

Examples the use of [ocele] are:

 Orchiocele:  The prefix [orchi-] means "testicle" or "scrotum". Refers to a scrotal or testicular bulging, a scrotal hernia
• 
Hydrocele: The root term  [-hydr-] means "water". A watery dilation. Usually used to refer to the accumulation of fluids in the scrotum
• 
Hydatidocele: Refers to a dilated cyst containing hydatids, the larval form of the tapeworm Echinococcus granulosus or Echinococcus multilocularis
Enterocele: The root term [-enter-] means "intestine" or "small intestine". The bulging of the small intestine into the vagina because of weakness of the vaginal wall
Cystocele: The root term [-cyst-] means "bladder" or "sac". The bulging of the urinary bladder into the vaginal canal because of weakness of the vaginal wall
Cystourethrocele: A combination of root terms; [-cyst-] means "bladder" or "sac" and [-urethr-] means "urethra". The bulging of the urinary bladder and urethra into the vaginal canal
Myelomeningocele: A combination of root terms; [-myel-] means "spinal cord" (also "bone marrow") and [-mening-] means "menynx". The herniation of the spinal cords and its meningeal coverings into the back, creating a bulge
Varicocele: The root term [-varic-] means "varix" or "sac". A bulging of the skin caused by varices

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-penia

The suffix [-(o)penia] arises from the Greek [πενία] or [penia], meaning "poverty" or "to lack". In medical terminology this suffix is used to mean "a deficiency", or "lack of". Examples of its use are:

Leukopenia or leukocytopenia:  A combination of  root terms;  [leuk], means "white", and [-cyt-] means "cell".  A white cell deficiency
• 
Pancytopenia: The prefix [pan] means "wide" or "many". The term refers to the deficiency of a wide variety of cells, in this case, blood cells
• 
Neutropenia or neutrocytopenia: Refers to the deficiency of neutrophil cells  or polymorphonuclear leukocytes, The most common type  of white blood cells
Osteopenia: The root term [-oste] means "bone". A bone deficiency, not low enough to be classified as osteoporosis
Erythropenia: The root term [-erythr-] means "red". A deficiency of red blood cells

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Right coronary artery

The right coronary artery (RCA) is one of the two branches that arises from the ascending aorta and provide blood supply to the heart. The RCA begins at the coronary ostium, situated usually within the right sinus of Valsalva found in the aortic valve, one of the semilunar valves of the heart.

The RCA gives off in its initial course two arteries: the conus artery, which gives blood to the conus arteriosus, the outflow tract of the right ventricle, and the artery to the sinuatrial (SA) node, a component of the conduction system of the heart.

The RCA descends in the atrioventricular sulcus, giving off a series of small right ventricular branches and a couple of small right atrial branches, it then bends around the acute margin (margo acutus) and passes to the posterior surface of the heart. Just before the RCA bends posteriorly, it will give off the acute marginal artery, usually a thin, longer branch that extends towards the cardiac apex.

Heart, anterior view. SVC: superior vena cava. RCA: right coronary artery; IVC: inferior vena cava; CFX: circumflex artery; LMCA: left main coronary artery; LAD: left anterior descending artery

Heart - Anterior view. Click on the image for a larger version.

In its posterior trajectory the RCA gives off a couple of small posterior right ventricular arteries and then ends at the crux cordis, where the RCA gives off the posterior interventricular artery, commonly known as the posterior descending artery (PDA). The RCA will also give off the posterolateral artery, which, situated in the atrioventricular sulcus, extends the vascular territory of the RCA into the region of the left ventricle. This origin of the PDA from the RCA is subject to anatomical variation, which gives origin to the concept of coronary dominance.

Arising from the terminal portion of the RCA (sometimes from the posterolateral artery) is the artery to the atrioventricular (AV) node, another component of the conduction system of the heart. It is easily understood that stricture or stenosis of the RCA (depending on location) can then lead to damage of the conduction system of the heart.

Human heart and coronary artery anatomy and pathology are some of the many lecture topics developed and presented by Clinical Anatomy Associates, Inc.

Image property of:CAA.Inc.Artist:Victoria G. Ratcliffe

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