Cervical: C1 - C5

Innervates muscles of neck and extend into thoracic cavity, where they control diaphragmatic muscles. Major nerve: Phrenic...which provides entire nerve supply to diaphragm.

Brachial: C5-T1

Innervates pectoral girdle and upper limbs. Major nerves: Radial nerve, median nerve, ulnar nerve.

Lumbar: T12 - L4

Innervates pelvic girdle and lower limbs. Major nerves: Genitofemoral nerve, lateral femoral cutaneous nerve, and femoral nerve.

Sacral: L4-S5

Innervates pelvic girdle and lower limbs. Major nerves: Sciatic nerve (which branches into tibial and fibular nerves) and pudendal nerve.