The second sacral ventral nerve roots contain efferent somatic nerve fibers corresponding to the second sacral spinal cord segment.  They emerge as two or three rows of rootlets from the antero-lateral sulci of the spinal cord.  Between adjacent rootlets are inter-radicular spaces, which contain small blood vessels.  
The roots pass obliquely infero-laterally as part of the cauda equina to their exit through the sacral canal, to join with the second sacral dorsal roots to form the second sacral spinal nerves.  They are larger in obliquity and length than the ventral roots above.

They are covered by a sleeve of pia mater, which is continuous with that of the spinal cord, and loosely invested by a prolongation of dura and arachnoid mater (the dural sleeve) almost as far as the spinal nerves.

Cauda Equina
The cauda equina is formed from the most caudal spinal roots.  As the spinal cord terminates before the vertebral column, the lower spinal roots descend inferior to the cord, as a divergent sheath, to reach their corresponding foramina.