Ribs and vertebral bodies have been resected bilaterally between the second and the ninth thoracic segments. The periosteum (6) which covered the inner surfaces of the ribs have been preserved in most areas. The anterior longitudinal ligament (23), with remnants of the intervertebral discs attached, has also been retained in part. The lungs have been inflated and are visible through the intact costal pleura. The proximal parts of the III-VII spinal nerves have been positioned on the pleura in such a way that their dorsal and ventral roots, dorsal rami and communications with the sympathetic trunks are visible. These components are labeled for the left seventh thoracic nerve (8, 9, 10). The intercostal arteries and veins have been cut off in various ways.