Ulnae

Part of speech: noun

Definitions

1. A pair of long bones in the forearm that extend from the elbow to the wrist
2. Each bone in this pair is situated on the inner side of the forearm, running parallel to the other bone
3. Referring to the linear structures involved in arm movement, contributing to the formation of the human wrist joint

Etymology: "Ulnae" is the plural of "ulna," the bone of the forearm on the little-finger side, and the word "ulna" itself is simply the Latin word for "elbow." That is the surprise: the bone is named for the joint it helps form, not for the arm as a whole. Latin "ulna" also meant the forearm and, by extension, a measure of length based on it, which is why it is a doublet of "ell," the old English unit of cloth measurement that came to English through a different route. Because the two words descend from the same Latin source but entered English by separate paths, "ell" and "ulna" are a textbook pair of doublets. One became an everyday measuring term, while the other stayed in the vocabulary of anatomy. The plural form "ulnae" follows the Latin pattern for words of this type, so it is the form most often used in technical writing.