ulnaris

Ulnaris is the Latin adjective meaning “of the ulna” and is used in anatomical terminology to indicate a relation to the ulna, the medial bone of the forearm. It is not a standalone structure but appears in names of bones, nerves, muscles, and ligaments associated with the ulna.

In common anatomical usage, ulnaris appears in terms such as nervus ulnaris (the ulnar nerve) and several muscles that act on the ulnar side of the forearm and hand, including musculus flexor carpi ulnaris and musculus extensor carpi ulnaris. The term helps specify the location and function of these structures relative to the ulna.

Nervus ulnaris is one of the major nerves of the upper limb. It originates from the brachial plexus and travels along the medial aspect of the arm and forearm to the hand. It provides motor innervation to most intrinsic hand muscles (notably the interossei, the hypothenar muscles, and the medial two lumbricals) and supplies sensation to the medial one and a half digits on both the palmar and dorsal surfaces. Injury or compression of the ulnar nerve can lead to weakness of hand muscles and altered sensation, sometimes described as ulnar neuropathy.

Muscles that bear the ulnaris designation include flexor carpi ulnaris and extensor carpi ulnaris, which act to flex or extend the wrist while adducting it toward the ulnar side.

See also ulna, ulnar nerve, carpus, and related ligaments and muscles.