Wrist and biceps?
C5 and C6
Everything on front of arm?
C5 and C6
Triceps?
C7 and C8
Everything on back of arm?
C7 and C8
Knee jerk?
L3 and L4 keeps your foot of the floor
Ankle jerk?
S1 and S2
Diaphragm?
C3, C4, C5 keeps the diaphragm alive (phrenic)
Erection of penis?
S2, S3, S4 keeps your dick off the floor (pudendal)
Anal?
S4 and S5
Plantar/achilles?
S1
Jaw?
C5