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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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Acute marginal artery

The acute marginal artery is the longest branch of the right coronary artery on the anterior aspect of the heart and extends towards the cardiac apex. The name reflects the fact that this artery runs along the anteroinferior border of the heart called the “margo acutus” in Latin or the “acute margin”.

The acute marginal artery is used in coronary angiography to denote the lower border of the heart.

The acute marginal artery may have a higher origin on the right coronary artery or it may arise from one of the lower right ventricular arteries. There are anatomical variations of the acute marginal artery where this artery actually may provide blood supply to the left ventricle of the heart.

Sources:
1. "Gray's Anatomy" 38th British Ed. Churchill Livingstone 1995
2. “Variable anatomy of the right coronary artery supply to the left ventricle”  Adams, J. Treasure, T. Thorax 1985;40:618-620

LAD= left anterior descending artery; lca=left conal artery; OM1= obtuse marginal artery 1; rca= right conal artery; acv=anterior coronary veins; RCA=right coronary artery
Image modified from the original courtesy of Bartleby.com