169. Veins of Spinal Cord and Vertebral Column 174. Nerves of Back 175. Suboccipital Triangle 176. Lumbar Region of Back: Cross Section 177. Typical Thoracic Spinal Nerve: Cross Section 180. Arteries of Mammary Gland 185. Anterior Thoracic Wall 186. Anterior Thoracic Wall (continued) 187. Anterior Thoracic Wall: Internal View