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.

You are welcome to submit questions and suggestions using our "Contact Us" form. The information on this blog follows the terms on our "Privacy and Security Statement" and cannot be construed as medical guidance or instructions for treatment.

We have 335 guests online

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".

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

 "Clinical Anatomy Associates, Inc., and the contributors of "Medical Terminology Daily" wish to thank all individuals who donate their bodies and tissues for the advancement of education and research”.

Click here for more information

abebooks banner




From the Latin [vena], meaning "vein". Some early authors postulated that the term derivates from the Latin word [venio] meaning "to come", because the blood in the veins "comes in" to the heart. There are two root terms meaning "vein", the first is the Latin derivated [-ven-], as in the terms venous and intravenous. The second root term is Greek [-phleb-], as in the terms phlebectomy, phlebotomy, and phlebotomist. Peripheral veins have internal one-way valves, while most of the central veins (in the trunk) do not present with valves. Failure of a peripheral venous valve can lead to dilation of the vein, condition called a varix.

Venous: pertaining to a vein
Intravenous: inside or within a vein
Phlebectomy: removal of a vein
Phlebotomy: to open a vein

Back to MTD Main Page Subscribe to MTD


The term [carotid] is Greek and means "to sleep", "to stupefy", or "to put to sleep". This arises from the observed fact that compression of the large arteries in the neck caused animals to fall asleep (Rufus of Ephesus c.100BC). Andrea Vesalius proposed the name "soporalis arteriae", but the Greek term [carotid] is what we use today. 

The carotid arterial system is bilateral. On the right side, the right common carotid artery arises from the brachiocephalic trunk, while on the left side the left common carotid artery arises from the aortic arch. The common carotid artery divides into an external and an internal carotid artery. The internal carotid artery presents a dilation close to its origin, the carotid sinus, and then heads superiorly to enter the carotid canal of the temporal bone. The internal carotid artery does not give any branches in the neck region and ends providing important branches to the eye and the arterial circle of Willis, which supplies part of the brain.

The external carotid ends giving origin to two arteries, the superficial temporal artery and the maxillary artery. The external carotid artery gives off six named branches:

• Superior thyroid artery
• Lingual artery
Facial  artery
Ascending pharyngeal artery
 Occipital artery
Posterior auricular artery

"The ancient Hellenic and Hippocratic origins of head and brain terminology" Panourias IG, el al Clin Anat 2012 Jul;25(5):548-581
2. "The origin of Medical Terms" Skinner, AH, 1970
Images property of: CAA.Inc. Artist: Dr. E. Miranda
Right carotid artery system - anterior view
Right carotid artery system - anterior view
Click on the image for a larger version
Back to MTD Main Page Subscribe to MTD

Wilhelm Konrad Roentgen

This article is part of the series "A Moment in History" where we honor those who have contributed to the growth of medical knowledge in the areas of anatomy, medicine, surgery, and medical research.

Wilhem-Conrad Roentgen
Prof. Wilhem-Conrad Roentgen

Wilhelm Konrad Roentgen (1845 - 1923). A German physicist, Professor Roentgen started studying Physics at the University of Ultrech, and receiving his degree from the University of Zurich. Having observed fluorescence on a paper covered with barium platinocyanide close to an active cathode ray. Suspecting the presence of "invisible rays", he devised an experiment to prove this. 

On November 8, 1895 he confirmed his theory and called these invisible-to-the-eye emissions "X"-rays. He also observed the action of these "X"-rays on photographic plates, and that these rays could traverse through the human body, showing the bones. In fact, the first "roentgenogram" was an image of his wife's hand. If you hover over Professor Roentgen's image, you will see an depiction of this historic image. This image marks the beginning of the science of Radiology.

Professor Wilhelm Konrad Roentgen received many awards, medals, and recognitions. In 1901 he was awarded the Physics Nobel Prize.


2. "The origin of Medical Terms" Skinner, HA; 1970

Both original images (1) and (2) are in the public domain and courtesy of the National Library of Medicine.
Thanks to Megan Ohse for suggesting this article

Sulcus / gyrus

Sulcus / gyrus and Brain, lateral view (
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.

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 Second image modified from the original image by Henry Vandyke Carter, MD., courtesy of
Terms suggested by Sara Mueller.

Adam Christian Thebesius

This article is part of the series "A Moment in History" where we honor those who have contributed to the growth of medical knowledge in the areas of anatomy, medicine, surgery, and medical research.To search all the articles in this series, click here.

Adam Christian Thebesius (1686- 1732). German physician and anatomist, Thebesius studied in the University of Leiden, Netherlands, where he received his doctorate in 1708 with the thesis "De circulo sanguinis in corde" (on the circulation of the blood in the heart). In 1713 he became a member of the Royal Academy of Natural Scientists (Kaiserliche Akademie der Naturforscher), where he adopted the Latin name "Eyryphon". Besides his natural sciences and medical research, Thebesius developed an interest in astrophysics.

Extremely interested in coronary circulation, Thebesius injected dyes and fluids in the coronary arteries, veins, and coronary sinus. Along with Raymond Vieussens (1635-1713) , Thebesius described all these structures. Today his name is attached to the eponymic Thebesian veins (venae cordi minima), and the Thebesian valve guarding the exit of the coronary sinus into the right atrium of the heart. Both these structures were mentioned in his 1708 doctoral thesis

1. “The Role of the Thebesian Vessels in the Circulation of the Heart” Wearn, J.T. J Exp Med. 1928 January 31; 47(2): 293–315
2. The Story Behind the Word. Some Interesting Origins of Medical Terms. Wain,H. 1958. 
3. The Origin of Medical Terms. Skinner, H.A. 1970

Adam Christian Thebesius

Original image courtesy of Images from the History of Medicine at

Back to MTD Main Page Subscribe to MTD

Ventricular system of the brain

The ventricular system of the brain is an interconnected system of cavities and ducts within the brain through which cerebrospinal fluid (CSF) circulates. The CSF is produced in the choroid plexuses located within the ventricles.

There are two large curved lateral ventricles, each found within a cerebral hemisphere. They connect with the third ventricle via an opening called the "foramen of Monro". The third ventricle connects with the fourth ventricle by way of a slender canal called the "cerebral aqueduct" or the "aqueduct of Sylvius".

The third ventricle is found deep within the brain between the right and left diencephalic portion of the cerebrum.

The fourth ventricle is located between the pons of the brain stem anteriorly and the cerebellum posteriorly. This ventricle has a rhomboidal shape and it connects with the external aspect of the brain and the subarachnoid space. Failure of this CSF drainage from the ventricles to the subarachnoid space can lead to pathological accumulation of CSF within the ventricles and hydrocephalus.

The superior image shows a lateral view of the brain with a superimposed image of the ventricular system. If you click on this image, you will see a superior view of a cast of the ventricular system (by Retzius). More information on these images at

The inferior image shows a posterior view of the brain stem and the cerebellum which has been opened in the median plane to expose the 4th ventricle. Click on the image to see a larger version.

Ventricular system of the brain (
Superior image courtesy of:
4th ventricle - Human brain dissectionInferior image property of: CAA.Inc.
Photographer: Efrain Klein

Back to MTD Main Page Subscribe to MTD