It extends from the hypothalamus rostrally to the spinal cord caudally, and contains both descending and ascending fibers.
Descending fibers arise in the hypothalamus to project directly or indirectly onto autonomic nuclei and lower motor neurons of the brainstem and spinal cord; the descending component is involved in controlling chewing, swallowing, salivation and gastrointestinal secretory function, and shivering.
Fibres arising from the nuclei of the reticular formation ascend in the DLF to terminate in the hypothalamus.
[citation needed] Fibers arising from the parabrachial area pass in the DLF to convey taste and general visceral sensation from the nucleus tractus solitarius to the posterior nucleus and periventricular nuclei of the hypothalamus.
[citation needed] A small ascending dorsal serotonergic pathway arising from the ventral and dorsal superior raphe nuclei initially travels in the DLF, with some of its fibres terminating in the periaqueductal gray of the midbrain, and the posterior hypothalamus; the majority of its fibers however pass beyond the DLF in the medial forebrain bundle, here uniting with fibres of the more substantial ventral serotonergic pathway to commonly terminate diffusely across structures of the forebrain.