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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

Johann Gottfried Zinn

Johann Gottfried Zinn
(1727–1759)

Anatomist and botanist, Johann Gottfried Zinn was born on December 6, 1727 in the city of Ansbach, Germany. He started his medical studies in his native city, becoming later a student of Dr.  Albrecht von Hallers at the University of Göttingen, and received his MD in 1749.

He left for Berlin to continue his studies but came back shortly thereafter. He became a professor of anatomy at the University of Göttingen and in 1753 he also became the director of the botanical garden in the same city.

He is known for his anatomical treatise on the anatomy of the human eye: “Descriptio anatomica oculi humani iconibus illustrata”. Because of this, his name has become an eponym in the “Zonule of Zinn”, a ring of strands that forms a fibrous band connecting the ciliary body with the capsule of the lens of the eye. Zonule of Zinn is sometimes referred to as the suspensory ligaments of the lens, or the “ligament of Zinn”. His name is also attached to the anular ring tendon found in the posterior aspect of the eye, the "anular tendon of Zinn". This ring serves as attachment for all the extraocular muscles of the eye and the optic nerve passes through the center of the ring.

Carol Linné (Carolus Linneaus) named a genus of flowers in the family Asteraceae known vernacularly today as “Zinnia” in his honor. Hover your cursor over his portrait to see the flower.

The chapter on orbital anatomy of his anatomy book, taken from the second edition in 1780, has been translated and the first of three parts is published in an issue of “Strabismus”

His book "Catalogus Plantarum Horti Academici Et Agri" can be seen online here.

His life was short, dying at the early age of 32, but his name lives on in the name of a beautiful flower.

Sources:
1. “Johann Gottfried Zinn" Simonz, HJ Strabismus – 2004, Vol. 12, No. 2, p. 125 
2. "Anatomical Description of the Human Eye" Zinn, JG Strabismus, 13:45–52, 2005 
Images: Public Domain by Wikipedia Commons. 1. Own work I_am Jin, and H. Wilhem Dietz


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Proximal / Distal

The term [proximal], from the Latin [proximus] meaning "next" and its counterpart [distal], from the Latin [distans] meaning "distant", have been poorly defined and this causes misunderstanding in the proper use of these terms. This is particularly true in the medical industry.

The classical definition of [proximal] are "nearest, closer to the origin, closer to the point of reference" and also "closer to the beginning", or "opposite of distal". [Distal] is, of course, the opposite. All of these definitions are lacking a consensus between the participants in a conversation. This lack of proper definition could potentially lead to problems in an interventional situation and a patient could be injured.

In our lectures and training materials we use a working definition1 as follows: “Proximal has two meanings: 1- Closer to the point of attachment, where one end of the attached structure is free, and 2- Closer to the point of origin of flow of a fluid” Distal is of course, opposite to proximal.

In the first acception of the word, a clear example is the attachment of the upper and lower extremities. Moving away from the shoulder or the hip joint is a distal movement. “The wrist joint is distal to the elbow joint”. The same is true for the Fallopian (uterine) tube, where the proximal attachment of the tube is to the uterus and the free distal end of the tube is its fimbriated end.

In the second acception of the word, in any anatomical structure, organ, or system where there is flow of a fluid (food, urine, bile, blood, etc.) it is accepted that normal flow (antegrade flow) goes from proximal to distal and that abnormal flow (retrograde flow) goes from distal to proximal.

1. Use of this definition is permitted, as long as CAA, Inc. is credited, or a link to this article is posted with it.
Image property of: CAA.Inc. Artist: Victoria G. Ratcliffe