Q: I’m puzzled about why the “brachiocephalic artery” is commonly referred to as the “innominate artery.” In other words, why is an artery with a precise name vaguely referred to as an anonymous artery?
A: Let’s first look at the adjective “innominate,” which the Oxford English Dictionary defines as “not named, unnamed, anonymous.”
English adapted the term in the 17th century from the late Latin innominatus, which was used in the writings of the early sixth-century philosopher Boethius.
The earliest example in the OED is from Some Yeares Travels Into Divers Parts of Asia and Afrique (1638), by Thomas Herbert: “Zeyloon … was not innominate to the Antients.” (Zeyloon, once an alternate spelling of Ceylon, is now known as Sri Lanka.)
By the 19th century, the term was being used, sometimes in English and sometimes in Latin, to refer to various bones, arteries, and veins in the human body.
The first Oxford example is from Phillips’s New World of Words, a 1706 edition edited by John Kiersey: “Innominata Ossa … the Nameless Bones, two large Bones plac’d on the sides of the Os Sacrum.”
The dictionary’s earliest example of “innominate artery” is from George Rolleston’s Forms of Animal Life (1870): “The aorta [in birds] divides after a very short course into three great trunks, by giving off two subequal innominate arteries.”
Interestingly, the term “brachiocephalic artery” appeared in print dozens of years before “innominate artery,” according to OED citations.
The Cyclopædia of Anatomy and Physiology (1836-39), edited by Robert Bentley Todd, has an entry for the “brachio-cephalic artery.”
So the term that you consider more precise apparently showed up before the one that you consider fuzzier. Hmm!
So why is the “brachiocephalic artery,” which supplies blood to the right arm, the head, and the neck in humans, commonly referred to as the “innominate artery”?
Mosby’s Medical Dictionary (8th ed.) says the term “innominate” is sometimes used for body parts that have descriptive names rather than precise ones (like the aorta, the femur, or the tibia).
“The term is traditionally applied to certain anatomic structures, often identified by their descriptive name, such as the hip bone and brachiocephalic artery,” the medical dictionary explains.
In other words, the “brachiocephalic artery” is referred to as nameless because “brachiocephalic” here merely indicates that the function of the artery involves the arm and head.
We can understand if you’re still puzzled by all this. The idea of a descriptive name being nameless strikes us as odd too. But who are we to complain, no matter what it’s called—as long as surgeons can find it?