160. Spinal Cord and Ventral Rami in Situ 161. Relation of Spinal Nerve Roots to Vertebrae 162. Dermatomes 163. Sympathetic Nervous System: Schema 164. Parasympathetic Nervous System: Schema 165. Spinal Membranes and Nerve Roots 166. Spinal Nerve Origin: Cross Sections 167. Arteries of Spinal Cord: Schema 168. Arteries of Spinal Cord: Intrinsic Distribution