[Thoracic vertebral nerve]

When studying phylogenetic transformations of the sympathetic trunk, a theoretical possibility has been substantiated that in Mammalia a caudal continuation of the vertebral nerve in the thoracic area can exist. By means of some embryological and anatomical methods, in man and in certain animals (cat, dog), together with the cervical, the thoracic vertebral nerve has been revealed. The latter has an appearance of a plexus situating on the rudimentary thoracic vertebral artery wall and is formed at the expense of the multisegmentary distribution of the gray connective branches fibers. Anatomical manifestation of multisegmentarity of the gray connective branches connections is a division of these branches into cranial and caudal fasciculi and their spreading in the foramens between the transversal processes of the thoracic vertebrae and the necks of the corresponding ribs. In Mammalia the neck and the thoracic vertebral nerves combine into the vertebral neural trunk homologous to the secondary sympathetic trunk in birds. The thoracic vertebral nerve is a roundabout way for innervation of many somatic and vegetative structures. The pathogenetic mechanisms responsible for disturbances in the cervical vertebral nerve function, probably, somehow influence the thoracic vertebral nerve.