Posterior longitudinal fasciculus; Dorsal longitudinal fasciculus

The posterior longitudinal fasciculus is a white matter fiber tract located within the brain stem, specifically in the dorsal brainstem tegmentum. The posterior longitudinal fasciculus 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 posterior longitudinal fasciculus consists of myelinated axons carrying information between neurons. The posterior longitudinal fasciculus, carries both ascending and descending fibers, and conveys visceral motor and sensory signals.