lulna

Lulna is not a standard term in anatomy; it is typically a misspelling or variant of ulna, the forearm bone on the side of the little finger. In most contexts, the ulna is the bone referred to when discussing this structure.

The ulna is a long bone that runs parallel to the radius on the medial side of the forearm in the anatomical position. Its proximal end features the olecranon and coronoid processes, which together form the trochlear notch that articulates with the trochlea of the humerus to permit elbow flexion and extension. The proximal end also contains the radial notch, where the head of the radius articulates to form the proximal radioulnar joint. The interosseous membrane binds the ulna to the radius along their lengths, enabling force transmission and forearm stability.

Distally, the ulna has a head and a styloid process. The distal radioulnar joint connects the ulna to the radius to allow forearm rotation. At the wrist, the ulna is separated from the carpal bones by the triangular fibrocartilage complex, so it does not form a direct bony wrist joint; the radius mainly articulates with the carpals.

Function and clinical relevance: the ulna provides structural support for the forearm, serves as a site for muscle attachment, and participates in elbow and forearm movements, particularly pronation and supination with the radius. Fractures of the ulna are common and can occur in isolation or as part of forearm injuries, such as Monteggia fractures that involve dislocation of the radial head.