ulna

American  

[uhl-nuh] / ˈʌl nə /

noun

plural

ulnae, ulnas

1. Anatomy. the bone of the forearm on the side opposite to the thumb.

2. a corresponding bone in the forelimb of other vertebrates.

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ulna British  

/ ˈʌlnə /

noun

1. the inner and longer of the two bones of the human forearm

2. the corresponding bone in other vertebrates

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Other Word Forms

• postulnar adjective
• ulnar adjective

Etymology

Origin of ulna

1835–45; < Latin: elbow; akin to Greek ōlénē, Old English eln ell ²

Explanation

Your ulna is a bone in your arm — it sits in the forearm beside the radius bone, connecting your pinky finger to your elbow. The ulna is longer than the radius, and you need it for things like turning a car's steering wheel and throwing a ball. Because the ulna extends to the very tip of the elbow, it's sometimes called the "elbow bone," and in fact ulna means "elbow" in Latin. Most animals have an ulna, although it's often at least partially fused to the radius.

Example Sentences

The researchers also found that Sahelanthropus had a relatively long femur compared to its ulna, which adds further support for bipedal behavior.

From Science Daily • Jan. 3, 2026

At the moment, Chiappe, May and paleontologist Pedro Mocho are locked in an intense discussion about the precise positioning of an ulna.

From Los Angeles Times • Nov. 15, 2024

Det Insp Nikki Deehan said excavations "first uncovered a tibia and fibula and a humerus, ulna, and radius bone relating to the lower left leg and right arm respectively".

From BBC • Jan. 25, 2024

Jefferson, who had a deep passion for natural history, had received several bones, including the ulna, radius and claws, of an unknown animal.

From Seattle Times • Sep. 15, 2023

Regarding them in passing from the radius towards the ulna, those grooves give passage to the tendons of the muscles whose names occupy the columns on p.

From Artistic Anatomy of Animals by Cuyer, ?douard