lateral funiculus

noun

: a longitudinal division on each side of the spinal cord comprising white matter between the dorsal and ventral roots

In upper cervical segments, nerve rootlets emerge through each lateral funiculus to form the spinal accessory nerve which ascends the vertebral canal lateral to the spinal cord and enters the posterior cranial fossa via the foramen magnum.

—Gray's Anatomy, 39th edition

compare posterior funiculus, ventral funiculus