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

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.

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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Abdominal aorta

UPDATED: The abdominal aorta is the fourth, last, and most distal portion of the aorta. It begins when the descending aorta passes through the aortic hiatus of the respiratory diaphragm, just about the level of the 11th or 12th thoracic vertebra. It ends inferiorly at the bifurcation of the aorta, anterior to the lower portion of the body of the 4th lumbar vertebra where the abdominal aorta is continuous with the right and left common iliac arteries.

The abdominal aorta gives off a number of paired (bilateral) and unpaired (single) arterial branches. The paired branches are:

Inferior phrenic arteries: provide blood supply to the respiratory diaphragm
Renal arteries: Provide blood supply to the kidneys
Gonadal arteries: Depending on the gender, they are called testicular or ovarian arteries, providing blood supply to the gonads
Lumbar arteries: There are four pairs of lumbar arteries, which pass posteriorly around the vertebral bodies and provide supply to the spine and the back.
Suprarenal arteries: These are several minute arteries that provide blood supply to the suprarenal glands. The suprarenal (adrenal) glands also receive several minute arteries that arise from the renal arteries and the inferior phrenic arteries.

The unpaired arterial branches of the abdominal aorta are: 

• Celiac trunk: Provides blood supply to the stomach, spleen, liver, and duodenum
• Superior mesenteric artery: Provides blood supply to duodenum, jejunum, ileum, and the right side of the colon
• Inferior mesenteric artery: Provides blood supply to the left side of the colon, and superior aspect of the rectum
• Middle sacral artery: This is the only branch of the aorta that arises from its posterior aspect, it descends providing blood supply to the sacrum and fifth lumbar vertebra

Abdominal aorta</span></span> </span><span style=

Abdominal aorta- Anterior view. Click on the image for a larger version.

Clinically, the abdominal aorta is divided by the origin of the renal arteries into a suprarenal and an infrarenal segment. This division is important for the surgical treatment of abdominal aortic aneurysms (AAA). To see a AAA, click here.

The suprarenal segment is bound laterally by the crura of the respiratory diaphragm. and its inferior boundary is the superior aspect of the highest renal artery (usually the left renal artery). It has branches that are critical for the blood supply of most of the digestive tract, the celiac trunk and the superior mesenteric artery, plus the inferior phrenic arteries and the suprarenal arteries. 

The infrarenal segment includes the renal arteries, the inferior mesenteric artery, gonadal arteries, lumbar arteries, and the middle sacral artery.

Image property of:CAA.Inc.Artist:Victoria G. Ratcliffe