A Grammatical Dictionary of Botanical Latin

Ulna,-ae (s.f.I), abl.sg. ulna: 1. The elbow; (as Eng.noun) “the postaxial or inner one of the two bones of the forearm … that in man forms with humerus the elbow joint and serves as a pivot in rotation of the hand …” (WIII).

2. (as a measure of length) two feet, approx. 65 cm.; “the average length of a man’s arm; about 24 inches” (Lindley); “a measure of about twenty-four inches” (Jackson); = ulnaris,-e (adj.B), q.v.

- longe lateque profusa, ad ulnas 4 — 5 interdum producta (S&A), longly and widely spread out, sometimes extended to 4-5 ells [8-10 feet].

NOTE: classically, both ulna,-ae (s.f.I), and cubitus,-i (s.m.II), q.v., mean ‘elbow,’ but the ulna is the anatomical elbow bone, the cubitus is “the elbow (serving for leaning upon)” (Lewis & Short). It is the cubitus that represents the measure of length = the “ell” q.v. Classically the cubitus = “the distance from the elbow to the end of the middle finger, an ell, a cubit” (Lewis & Short) or 1 1/2 feet, 18 inches, approx. 46 cm. The ulna,-ae (s.f.I), however, has come to represent a unit of length equivalent to two feet, 24 inches, = the brachium,-ii (s.n.II), q.v. and brachialis,-e (adj.B), q.v.

NOTE: in Classical Latin (Lewis & Short), the ulna is the anatomical bone of the elbow, the elbow bone. In poetic, but not concrete, language, it also may represent the whole arm as lying in a mother’s arms is actually lying at her elbow. Lewis & Short also indicate it to be a “measure of length” but did not translate it into inches or centimeters except to say it is an ‘ell,’ which is now considered to be the length of the cubitus; see cubitus,-I (s.m.II); see ell.

Ulna may also represent a fathom, “as much as a man can clasp with both arms” (Lewis & Short) = orgyalis,-e (adj.B), q.v.: fathom-long, 6 feet long or high; = orgya,-ae (s.f.I), abl. sg. orgya: fathom (1.83 m.), toise (6 feet, 1.95 m.), the distance between tips of middle fingers when arms are extended.