The dorsal longitudinal fasciculus (DLF) (not to be confused with the medial longitudinal fasciculus, nor the superior longitudinal fasciculus) is a white matter fiber tract located within the brain stem, specifically in the dorsal brainstem tegmentum. The DLF travels through the periaqueductal gray matter. The tract is composed of a diffuse brainstem pathway located in the periventricular gray matter comprising ascending visceral sensory axons and descending hypothalamic axons.
As with all white matter tracts, the DLF consists of myelinated axons carrying information between neurons. The DLF, carries both ascending and descending fibers, and conveys visceral motor and sensory signals.
Read more about Dorsal Longitudinal Fasciculus: Ascending Fibers, Descending Fibers