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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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Carotid

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

Sources:
1.
"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