Bilaterally, spinal white matter is divided into three regions (funiculi). The dorsal boundary between funiculi is the dorsolateral sulcus, where dorsal rootlets enter the spinal cord. The ventral boundary, where ventral rootlets exit the spinal cord, is less precise because ventral root fibers emerge more variably. Spinal white matter is connected across the midline by a ventral white commissure (ventral to central gray matter). (A septum (or fissure) completely separates dorsal funiculi.)