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

Antoine Louis

French surgeon, anatomist, and physiologist. Following his medical studies and a long career as a physiologist, Antoine Louis was named Permanent Secretary of the Royal French Academy of Surgery. His other titles were those of Professor of the Royal Academy, Consultant Surgeon of the Armies of the King, member of the Royal Society of Sciences of Montpellier, Inspector of the Royal Military Hospitals, and Doctor in Law of the University of Paris. As a member of these academies Louis was instrumental in the design and construction of the guillotine. Initially called the "Louisette", this device was later named after another French physician in the same committee, Dr. Joseph-Ignace Guillotin.

Antoine Louis' name is better know to history as the eponymic origin of the "sternal angle" also know as the "Angle of Louis" and synonymously (probably by misspelling or translation) the "angle of Lewis", and "angle of Ludwig". This anatomical landmark is extremely important as it serves as a superficial landmark for important anatomical occurrences (click here).

As a point of controversy, there are some that contest the history of this eponym adjudicating it to Pierre Charles Alexander Louis (1787-1872), another French physician dedicated to the study of tuberculosis.

1. Srickland, N; Strickland A Angle of Louis, More Than Meets the Eye. MedTalks:
2. Ramana, R. K., Sanagala, T. and Lichtenberg, R. (2006), A New Angle on the Angle of Louis. Congestive Heart Failure, 12: 197–199
. "The origin of Medical Terms" Skinner, HA; 1970

 "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”.

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UPDATED: The term [plexus] comes from the Latin term [plectere] meaning " to twine, or to braid". In anatomy, the term [plexus] refers to a group of structures that are intertwined or form a meshwork.  The plural form is [plexuses], although the Latin plural form [plexi] is also correct. Gabrielle Fallopius used the term to denote "a tangle of nerves"

There are many plexuses described in the human body. Most are formed by nerves, but there are many that are lymphatic or vascular. The best known are the plexuses of nerves formed by the ventral rami of the spinal nerves. These are the cervical plexus, the brachial plexus, the lumbar plexus, and the sacral plexus. The image depicts the brachial plexus. For a larger version, click on the image, and for further information on the cervical and brachial plexuses, click here

Images and links courtesy of:www.bartleby.com

Brachial plexus (www.bartleby.com)

One of my pet peeves...


Say the following words out loud: "DISSECT" and "DISSECTION", then read on...

This is very high up on my list of personal annoyances or pet peeves. It was first brought up to my attention by Aaron Ruhalter, MD in his lectures. I was elated to find an article by Dr John H. Dirckx that took on the topic of the pronunciation of these terms. Dr. Dirckx states that the word should be pronounced with a short "i" as in "dissent"

The words “anatomy” and “dissection” are actually synonymous.  Anatomy has a Greek origin. "Ana" means “apart” and “otomy” is the “process of cutting”: “to cut apart”.

Dissection has a Latin origin and means exactly the same! In fact, for many years the term “to anatomize” was used instead of “ to dissect”! Where is the problem? In the pronunciation! “Dissection” should rhyme with “dissent”, "kissed", and "missed"

An argument could be made that the wrong pronunciation (dai-ssect) is so prevalent that it should be accepted. I disagree, the wrong pronunciation of a word does not make it acceptable.

Further to this argument is a listing of words that include the term (-iss-) which you can read online here. I challenge the audience to find one instance, besides "dissect" and "dissection" where the term is pronounces "ais" instead of "iss".

Other pet peeves:

- Using the word "leg" to mean "lower extremity" as the leg is only a segment of the lower extremity: click here
- Using the term "ramus" instead of "ramus intermedius" for an anatomical variation of the cardiac vasculature: click here
- Using the term "thoratomy" instead of the proper term "thoracotomy": click here

... do not get me started on anatomical and terminological pet peeves...

1. "The Doctor's Dyslexicon: 101 Pitfalls in Medical Language" Dirckx, JH Am J Dermatopath 2005 Vol: 27(1):86. DOI: https://doi.org/10.1097/01.dad.0000148282.96494.0f
2. The Free Dictionary :https://www.thefreedictionary.com/words-containing-iss

Pemphigus / pemphigoid

The term pemphigus refers to a rare group of autoimmune intraepidermal diseases characterized by blistering, pustules, or vesicles on the skin and mucous membranes. The mode of action of the disease is still not clear, but a key component is acantholysis, the disruption of the normal mechanisms of intercellular adhesion, which leads to intraepidermal blister formation.

There are several types of presentations of this disease such as p. vulgaris, p. foliaceus, p. vegetans, etc. One catastrophic presentation of this disease is ocular cicatricial pemphigoid. The pemphigoid disease progresses creating a symblepharon (adhesive attachments between the conjunctiva covering the sclera and the mucosa covering the posterior aspect of the eyelids. Eventually the disease may extend over the cornea. The accompanying image depicts a case of complete keratinization of the ocular surface in a patient with ocular cicatricial pemphigoid.

Complete keratinization of the ocular surface in patient with ocular cicatricial pemphigoid
Complete keratinization of the ocular surface in patient with ocular cicatricial pemphigoid.
Click on the image for a larger depiction 
The root term pemphig- derives from the Greek [πεμφίγος] meaning a pustule or blister; the suffix -oid  is also Greek [ειδής] meaning “similar to” of “kind of”. Therefore the medical term pemphigoid means “similar to blisters”

There is discussion as to when was this word first used, but it looks as though it was first published in 1763 in the book “Pathologia Methodica Practica, seu de Cognoscendis Morbis” by the French physician and botanist Francois Boissier de la Croix de Sauvages (1706 – 1767)

1. “Revue D’Histoire Des Sciences” Louis Dulieu, 1969
2. "Etymology of Pemphigus" Holubar, K. J Am Acad Dermat 1989:21, 155-156
3. "Pemphigus" Korman, N. J Am Acad Dermat 1988: 18/6  1219-38
4. “Ocular Cicatricial Pemphigoid” Khan R,. McDermott M., Hwang, F. Am Acad Ophthalm Eye Wiki https://eyewiki.aao.org/Ocular_cicatricial_pemphigoid

Image courtesy of EyeWiki


The root term [-brachi-] comes from the Latin word [brachium] meaning "arm". Do not confuse with [-brachy-], which means "small" or "short".

It must be pointed out that there is an important discrepancy between the vernacular use of the term "arm" (as the whole upper extremity) and the anatomical "arm". In human anatomy the "arm" is only the portion of the upper extremity found between the shoulder joint superiorly and the elbow joint inferiorly. In some radiology studies, the arm is referred to as the "upper arm" so as not to include the forearm. This use of the term "upper arm" is incorrect and should be avoided by medical professionals.

Examples of the use of this root term in human anatomy and pathology are:

• Brachialis: A flexor muscle in the upper extremity

• Brachial plexus: A plexus of nerves related to the upper extremity

• Brachioradialis: A flexor muscle that extends from the arm to the forearm

Infraspinatus muscle

The infraspinatus muscle is a thick, triangular muscle and one of the four muscles that forms the rotator cuff. It  is found in the posterior aspect of the scapula, in its infraspinous fossa, inferior to the scapular spine. The muscle is covered on its posterior aspect by a thick fascia, the infraspinatus fascia. This fascia separates the infraspinatus muscle from the teres minor and teres major muscles.

The muscle originates from the infraspinous fossa and from the deep aspect of the infraspinatus fascia. The muscular fibers converge superolaterally for form a tendon that inserts into the the greater tubercle of the head of the humerus. The tendon hugs the glenohumeral joint capsule and is separated from it by a small bursa. Some of the tendon fibers insert into the joint capsule.

The infraspinatus is the main external rotator of the shoulder. When the arm is fixed, it adducts the inferior angle of the scapula.

It receives innervation by way of the suprascapular nerve (C5, C6), which arises from the superior trunk of the brachial plexus.

Infraspinatus muscle - Image modified from the original by Henry VanDyke Carter, MD. Public domain
Infraspinatus muscle.
Click on the image for a larger depiction 
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.

Note: The side image modified from the original by Henry VanDyke Carter, MD. Public domain. Animated image below by Wikimedia Commons - Anatomography [CC BY-SA 2.1 jp (https://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)]

Anatomography [CC BY-SA 2.1 jp (https://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)]

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

Levator scapulæ muscle

The levator scapulae muscle (levator anguli scapulæ) is a triangular multipennate muscle which extends between the cervical spine and the scapula. This muscle is deep to the sternocleidomastoid and trapezius muscle.

It is formed by discrete muscular slips that originate from the first four transverse processes (C1-C4). It can have an extra slip from C5 (as shown in the side image).

These muscular slips pass posteroinferiorly, joining, and inserting in the superior scapular angle and the scapular medial border between the superior scapular angle and the medial origin of the scapular spine. It may attach to the scapular spine.

There are other anatomical variations including muscular slips that may extend to the occipital bone or mastoid process, to the trapezius, scalene, or serratus anterior magnus muscles, or to the first or second rib.

It receives nerve supply from the fourth and fifth cervical nerves and by a branch from the dorsal scapular nerve. The dorsal scapular nerve arises from the C5 root of the brachial plexus.

It receives its blood supply from the dorsal scapular artery.

The function of this muscle depends on which bony element is fixed, the scapula or the cervical spine. When the spine is fixed, the levator scapulae elevates the scapula and pulls the superior portion of the medial scapular border superomedially. When only one scapula is fixed, the head and neck flexes and rotates ipsilaterally while it extends the neck contralaterally.

The order and shape of the muscular slips is interesting, as the slip from the transverse process of the Atlas (C1) twists posteriorly and descends to insert as the most posterior and inferior fibers in the medial border of the scapula. The other slips follow a similar pattern, which is what allows this muscle to rotate the neck. This indicates that the fibers of the levator scapulae muscle are spiral and the fibers follow the contour of the neck. This makes (to my knowledge) the levator scapulae the only spiral muscle of the body. This is shown as "A" in the second side image; "B" represents the misconception on the direction of the fibers in this muscle.

Since it is a common sign of stress and bad posture to raise the shoulders, this muscle can spasm, causing neck pain and in some cases be a trigger for headaches.

Note: The first side image shown in this article is from “Gray’s Anatomy” (1918) which is in the public domain. The second side image is from Arnold’s “Reconstructive Anatomy” (1968).

Levator scapulæ muscle - Image modified from the original by Testut and Latarjet. Public domain
Levator scapulæ muscle.
Click on the image for a larger depiction 

Levator scapulæ muscle fibers - Image modified from the original by Arnold 1968
Levator scapulæ muscle fibers.
Click on the image for a larger depiction

Note: Animated image below by Wikimedia Commons - Anatomography [CC BY-SA 2.1 jp (https://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)]
Anatomography [CC BY-SA 2.1 jp (https://creativecommons.org/licenses/by-sa/2.1/jp/deed.en)]

1. “Gray’s Anatomy” Henry Gray, 1918
2. "Tratado de Anatomia Humana" Testut et Latarjet 8th Ed. 1931 Salvat Editores, Spain

2. "Tratado de Anatomía 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
5. “Reconstructive Anatomy, A Method for the Study of Human Structure” Arnold, M. W.B. Saunders. 1968“Gray’s Anatomy” Henry Gray, 1918