_Thoracic Walls_: The parietal muscles of the thorax are innervated by the intercostal nerves and a very definite segmental association with the spine is traceable. _Diaphragm_: Phrenic nerve, which arises from fourth cervical chiefly; lower intercostals, especially eighth and ninth; and phrenic plexus of the sympathetic which may sometimes be reached from the fourth or fifth dorsal vertebrae through the gangliated cord. For motor disturbances of the diaphragm adjust fourth cervical. _Abdominal Muscles_: These are supplied by the lower intercostals and the transversalis and internal oblique make connection with L 1 by the iliohypogastric. Cremaster is supplied by L 1 and 2 by way of the genital branch of the genitofemoral. _Perineal Muscles_: The anterior perineal group are supplied by the perineal branch of the internal pudic which traces to the second, third, and fourth sacral nerves. The posterior perineal and ischiorectal region is also supplied by the sacral and coccygeal nerves. _Trachea and Bronchi_: Vagus and sympathetic filaments from first and second thoracic ganglia. The latter receive preganglionic fibres from first dorsal nerve in all probability, as this adjustment reaches the bronchi. _Lungs_: The third thoracic ganglia connect with the pulmonary plexus and establish a connection from third dorsal vertebra direct to the lung parenchyma. The _Pleurae_ have a similar connection or may sometimes be reached by the first dorsal. _Heart and Pericardium_: In 55% of all heart disease or improper action the second dorsal is responsible; in 40% the first dorsal, and perhaps in the remaining 5% the atlas or axis. The former nerves (T 1 and 2) furnish pre-ganglionic fibres which stream upward through the gangliated cord to terminate in the three cervical ganglia in relation with the dendrites of new neurons (amyelinic) which form the superior, middle, and inferior cardiac nerves and pass into the thorax to mingle with vagal fibres to form the superficial and deep cardiac plexuses, controlling the heart. Probably the upper cervicals occasionally affect the vagus through the loop between the first and second cervical nerves. _Thoracic Aorta_: Controlled by sympathetic from first thoracic ganglion or last cervical ganglion, and thus by seventh cervical or first dorsal vertebra.