Your patient reports that several days earlier he threw his back out when he bent from the waist and picked up a very heavy package. The pain was immediate and extended from his hip, down the back of the thigh, and into his leg and foot. As he lies on the examining table, you raise his leg by the foot keeping the knee extended and elicit intense pain over the distribution of the sciatic nerve. An MRI scan confirms your conclusion that your patient has a herniated intervertebral disk between the fourth and fifth lumbar vertebrae.

Herniation of the intervertebral disk between the fourth and fifth lumbar vertebrae most likely impinges on the roots of which spinal nerve?