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Medical Terminology Daily (MTD) is a blog sponsored by Clinical Anatomy Associates, Inc. as a service to the medical community, medical students, and the medical industry. We will post a workweek daily medical or surgical term, its 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

Thomas Willis, MD
Thomas Willis
(1621-1675)

An English physician and anatomist, Willis was born on his parents' farm in Great Bedwyn, Wiltshire, where his father held the stewardship of the Manor. He was a kinsman of the Willys baronets of Fen Ditton, Cambridgeshire. He graduated M.A. from Christ Church, Oxford in 1642. In the Civil War years he was a royalist, and was dispossessed of the family farm at North Hinksey by Parliamentary forces. In the 1640's Willis was one of the royal physicians to Charles I of England. He obtained his medical degree in 1646.

Thomas Willis might well be one of the greatest physicians of the 17th century.He is one of the founders of the Royal Society of London. He is remembered by his many publications, especially "Cerebri Anatome: Cui accessit Nervorum Descriptio et Usu", where he describes the arterial anastomoses at the base of the brain. This work is also the first detailed description of the vasculature of the brain. Willis described nine cranial nerves.

He is considered as the father of Neurology as a discipline. He used the term "neurology" for the first time in 1664. He described several neurological conditions

The Arterial Circle of Willis is a famous eponymous structure found at the base of the brain. It represents an anastomotic roundabout that connects the right and left sides as well as the carotid and vertebral arterial territories that supply the brain. Named after Thomas Willis, this structure was known well before him, but it was Willis who described its function.  If you click on the image or here, you will be redirected to a detailed description of this structure.

Sources:

1. "The legendary contributions of Thomas Willis (1621-1675): the arterial circle and beyond" Rengachary SS et al J Neurosurg. 2008 Oct;109(4):765-75
2. "Thomas Willis, a pioneer in translational research in anatomy (on the 350th anniversary of Cerebri anatome)" Arraez-AybarJournal of Anatomy, 03/2015, Volume 226, Issue 3
3. " The naming of the cranial nerves: A historical review" Davis, M Clinical Anatomy, 01/2014, Volume 27, Issue 1
4. "Observations on the history of the circle of Willis". Meyer A, Hieros, R.Med Hist 6:119–130, 1962


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Esophageal hiatus hernia

UPDATED: An esophageal hiatus hernia (also known as a hiatal hernia) is caused by a dilation of the esophageal hiatus and its component structures, the phrenoesophageal membranes (ligaments).

Since the intraabdominal pressure is higher than the intrathoracic pressure, abdominal contents -usually stomach and greater omentum- can herniate through the dilated esophageal hiatus into the mediastinum, the central region of the thoracic cavity. This presents as a hernia sac whose walls are formed by endothoracic fascia, phrenoesophageal membranes and parietal peritoneum. 

There are two main types of esophageal hiatus hernias. Type I is known as a "sliding hiatal hernia" and is characterized by a complete ascension of the esophagogastric junction and abdominal esophagus into the thoracic hernia sac. This is usually accompanied by a typical "hourglass image" in a radiographic assessment, and also presents with gastroesophageal reflux disease (GERD). Type I esophageal hiatus hernias are more common.

Type II esophageal hiatus hernia is known as a "paraesophageal hernia" and represent about 5 - 15% of esophageal hiatus hernias. In this case, the esophagogastric junction maintains its anatomical position inferior to the respiratory diaphragm, but the fundus and body of the stomach, along with some greater omentum herniate alongside the esophagus into the mediastinal region of the thoracic cavity. Although there can be GERD, this type of hernia usually presents with little symptomatology, and when it does, symptoms are related to ischemia or partial to complete obstruction. There are variations of type II hernia, which are classified as Type III and IV. Type IV, although rare, will include other viscera in the hernia sac, including colon, spleen, or even small intestine

Esophageal hiatus hernia in situ.The arrow points to stomach and greater omentum herniating into the thoraxEsophageal hiatus hernia, reduced. The dotted line shows the edge of the enlarged esophageal hiatus.

Images property of: CAA.Inc. 
Photographer: David M. Klein

The accompanying images above depict a Type I esophageal hiatus hernia. The superior image shows the hernia in situ where the stomach and greater omentum are still in the hernia sac. The inferior image shows the contents reduced and the abdominal esophagus being pulled into the abdominal cavity. The dotted line shows the dilated esophageal hiatus that needs to be repaired to prevent recurrence of the pathology.

The image below answers a question by Victoria Guy Ratcliffe, who asked via Facebook "What would it be if it feels like you've got a blockage right at the level of the heart? That's too high for a hiatal hernia, isn't it? " The image answers the question. It shows a dissection of the left side of the thorax. The anterior thoracic wall and the left lung have been removed. The heart is immediately superior and anterior to the esophageal hiatus, and the hernia sac of a Type I esophageal hiatus hernia is seen immediately posterior and in contact with the heart. Whether this means that you will "feel" the hernia, it is up for debate, as all these structures have visceral innervation. Most probably, a well-developed Type II esophageal hiatus hernia might interfere with swallowing at this level, causing the sensation she mentions. Thanks for the question, Tori.

Type I esophageal hiatus hernia<em>.</em>The hernia sac can be seen posterior to the heart

For additional information: "Approaches to the Diagnosis and Grading of Hiatal Hernia" Kahrilas et al Best Pract Res Clin Gastroenterol. 2008 ; 22(4): 601–616.


The seven hiatuses (openings) of the respiratory diaphragm

The term [hiatus] derives from the Latin word [hiare], meaning to "gape" or to "yawn". In human anatomy this term is used to mean an "opening" or a "defect". It must be pointed out that in anatomy (and surgery) the term "defect" does not necessarily mean "defective". In most cases a "defect" is a normal opening in a structure, such as the esophageal hiatus. The plural form is either [hiatus] or [hiatuses].

In the case of the respiratory diaphragm, there are seven such openings, seven normal hiatuses. On top of this, you can find an abnormal opening caused by incomplete congenital closure of the dome of the diaphragm, a congenital diaphragmatic hernia (CDH), also known as Bochdalek's hernia, found in the posterior aspect of the respiratory diaphragm.

The seven hiatuses of the respiratory diaphragm are:

• Esphageal hiatus

• Aortic hiatus

• Inferior vena cava hiatus

Respiratory diaphragm (www.bartleby.com)
Images and links courtesy of Bartleby.com
• Hiatuses (2) for the superior epigastric vessels, which are the inferior continuation of the internal thoracic (mammary) vessels. Also known as the hiatuses of Morgagni. A hernia in a newborn through this hiatus is also considered a CDH.

• Hiatuses (2) for the splanchnic nerves

Based on the above it is wrong (maybe not wrong, but incomplete) to say that a patient has a "hiatal hernia", as the term does not include which hiatus is involved. In fact the hernia of Morgagni is also a "hiatal hernia" as the hernia passes through a normal defect in the respiratory diaphragm. Come to think of it, it could also be a hernia in a hiatus somewhere else in the body, such as a hernia of Schwalbe, a type or pelvic diaphragm hernia.

Note: Thanks to DHREAMS of the Columbia University Medical Center for the link on CDH.


Esophageal hiatus

UPDATED: The esophageal hiatus is one of the seven hiatuses found in the respiratory diaphragm allowing passage of structures between the thorax and abdomen. As it name implies, the esophageal hiatus is the passageway for the esophagus. It also allows passage of the anterior and posterior vagus nerves, (CN X).

The hiatus is bound by two muscular crura, both of which arise from the right tendinous aortic crus. Since the intraabdominal pressure is higher than the intrathoracic pressure, there is a series of structures at the phrenoesophagogastric junction to close the esophageal hiatus.

The infradiaphragmatic parietal peritoneum reflects off the diaphragm towards the stomach to form its serosa layer (visceral peritoneum). At the same time the infradiaphragmatic fascia, also known as the  endoabdominopelvic fascia, splits into two components or limbs. These are the superior and inferior phrenoesophageal ligaments or phrenoesophageal membranes. (the root [-phren-] means "diaphragm"). These phrenoesophageal ligaments create a disc-like plug between the abdomen and the thorax. This "plug" is reinforced by a circular infradiaphragmatic fat pad. The phrenoesophageal ligaments are reinforced on their thoracic aspect by the endothoracic fascia.

Esophageal hiatus

Images property of: CAA.Inc. Artist: Dr. E. Miranda

The lower esophagus has a dilation (evident in the image) called the "esophageal ampulla", in relation to this dilation the circular muscle layer of the esophagus slightly thickens creating the so-called "lower esophageal sphincter". This area is not a true anatomical sphincter, but rather is a functional sphincter. 

The esophagogastric mucosal junction shows a marked transition in the shape of a wavy line. This is called the Z-line or the ora serrata. Extensions of the gastric mucosa and submucosa inferior to the ora serrata create a valve-like flap called the "gastroesophageal flap valve". When viewing this mucosal flap through and endoscope, it looks corrugated and flower-like, hence it is also called the "rosette". 

The congenital or pathological dilation of the esophageal hiatus can predispose to esophageal hiatus hernia.


Acetabulum

The word acetabulum is formed by the combination of the Latin root [acetum], meaning "vinegar", and the Latin suffix [-abulum] a diminutive of [abrum], meaning a "cup", "holder", or "receptacle". Thus formed, the word acetabulum means "a small vinegar cup".

Roman soldiers liked to drink their water mixed with a small quantity of vinegar, so as to reduce the sensation of thirst. This mix was called "Posca". An acetabulum was used to add specific quantities of vinegar to the water, so over time the acetabula (plural form of acetabulum) were considered measuring devices. It is said that they measured one cup, or 2 1/2 oz. of wine.

The anatomical acetabula are bilateral cup-like depressions in the os coxae which serve as a component of the coxofemoral joint (hip joint). They are found at the intersection of the three bony components of the os coxae, the ilium, ischium, and pubic bone and look anteroinferiorly.

Acetabulum
Image property of: CAA.Inc. 
Photographer:
David M. Klein
The acetabulum has several components:

• Acetabular margin: An incomplete circular bony edge or border that marks the edge of the acetabulum

• Acetabular notch: The area where the acetabular margin is incomplete

• Acetabular labrum: Labrum (Lat. :lip). The acetabular labrum is a complete circular ring of fibrocartilage found on the acetabular margin that helps maintain the head of the femur in place. It is not shown in the accompanying image

• Lunate surface: A smooth, half-moon shaped area on the floor of the acetabulum. It is covered with hyaline cartilage and allows for articulation with the head of the femur

• Acetabular fossa: The non-articular region of the floor of the acetabulum. It contains fat, vessels, and the ligament of the head of the femur

Interesting fact:  You may find that in older English anatomy books the acetabulum is referred to as the cotyloid cavity. The word cotyloid arises from the Greek [κοτυλοειδές] and means "similar to a cup". This separation in terms still exists when studying anatomy in other languages. For example, in Spanish the acetabulum is called "cavidad cotiloídea" or "cotilo", and in French it is called "cavité cotyloïde" or "cotyle". I guess the Greek soldiers did not drink vinegar with their water...


Sternal angle (of Louis)

UPDATED:The sternal angle is the term used to denote the angulation at the  joint between the manubrium and the body of the sternum. This transverse joint is called the "manubriosternal joint" and is a secondary cartilaginous joint of a type known as a symphysis. The angle varies between 160 and 169 degrees.

It is know eponymously as the "angle of Louis" named after Antoine Louis1 (1723-1792), a French physician. The importance of the sternal angle is that of an anatomical superficial landmark, which forms a horizontal plane which indicates a series of anatomical occurrences, as follows:

• Location of the cartilages of the second rib
• Beginning and end of the aortic arch
• Boundary between the inferior and superior mediastinum
• Location of the bifurcation of the trachea
• Posteriorly, the plane of the sternal angle passes trough the T4-T5 intervertebral disc
• Highest point of the pericardial sac, etc.

Sternal angle - Angle of Luis

Click on the image for a larger version.

Thoracic anatomy, pathology and surgery, are some of the many lecture topics developed and presented by Clinical Anatomy Associates, Inc.

1. Some authors contest the eponym, adjudicating it to Pierre Charles Alexander Louis (1787-1872), another French physician.
Image property of: CAA.Inc.. Artist: David M. Klein

In Search of Andreas Vesalius The Quest for the Grave, Lost and not yet found

My partner in crime and fellow traveler, Theo Dirix, has just published a new account of our common quest for the lost grave of Andreas Vesalius. Until the scientific results of our latest mission in Zakynthos in September 2017, will become public, this collection of articles published since 2014 represents a detailed and complete status quaestionis of a search that will never be the same anymore.


I'm proud and grateful to be part of a team he describes a most tenacious.

Following is a remarkable quote from the book: "The beast you have in your hands may appear as aged and stubborn: indeed, the texts collected here are not new and they regularly echo each other. The beast barks and growls: these words do not intend to examine or research but were meant to sell a project to potential sponsors. I feel the taste of the creature’s spit in my face, but pleading not guilty to any accusation of self-glorification, I do hope I managed to teach it a few tricks you will enjoy. While continuing to write about Vesalius’s death and his grave, black dogs may still be scratching at my hermitage. When I will finally throw open the doors to the beauty beyond, here’s hoping the encounter with the female spider will taste as fresh as a first kiss and be the beginning of something else."

No surprise some have described the book as: "a truly captivating story (a Live Adventure!) written in a fascinating, passionate and inspiring way. Theo Dirix, with his unique style is describing facts from his adventure to locate the grave of Vesalius and he is mentioning with great respect all his collaborators, the friends of Vesalius and those who share the same passion for Anatomy and Art." (Vasia Hatzi on Med in Art).

Cover of the book by Theo Dirix
Cover of the book by Theo Dirix.
Click on the image for a larger depiction

The book can be ordered here: https://www.shopmybooks.com/US/en/book/theo-dirix-32/in-search-of-andreas-vesalius. (English version of the website). More information about the author on his website www.theodirix.com. or here.


Personal note: Thanks to Pascale Pollier, a contributor to this website, for allowing us to publish this article, originally published on Vesalius Continuum.

I received a personalized copy from the author, Theo Dirix; Thank you very much for the recognition and the use of this website as reference in some of your comments. It is a great read for anyone even mildly interested in the life and specially the death and disappearance of the grave of Andreas Vesalius. There are several passages in the book that I will have to research and transform in articles for this blog.

For those who collaborated in the GoFundMe campaign because or our article entitled Do you want your name in a book? The Quest for the Lost Grave.... this is the book and the name of all the contributors are listed in it! 

The quest continues... Dr. Miranda