T1 and T2 thoracic spinal nerves supply the top of the chest, arms, and hands. T3, T4, and T5 nerves supply into the chest wall as well as aid in breathing. T6, T7, and T8 nerves supply into the chest and down into the abdomen. T9, T10, T11, and T12 nerves supply into the abdomen and lower in the back.