RESUMEN
Performing fetal operations on the walls of the thorax and abdomen requires detailed information dealing with the anatomical variability of the intercostal nerves (IN) in human fetuses. Therefore, our study aimed at determining the topographic and anatomical characteristics of the I-XII IN during the period of human ontogenesis. The study involved 70 specimens of fetuses aged 4-10 months, by means of macromicroscopic preparation, superficial staining of dissected vessels and nerves and morphometry. The variability of the topography and asymmetry of the trunks of IN and their branches were revealed. The direction of the lateral musculocutaneous branches of the inferior IN does not coincide with the direction of the muscle bundles of the external abdominal oblique muscle. The branches of the I IN are functionally different, since the superior branch branches out in the skin and vessels, and the inferior one - in the stratum of the internal intercostal muscle. The anterior musculocutaneous branches of the II-VII IN occur in the front of the parasternal neurovascular bundle and are related with each other, with parasternal nerve or with the nerve plexus of the internal thoracic artery. The trunks of adjacent IN relate to one another by means of rare connecting branches, numerous and diverse in shape links are observed between the anterior and lateral musculocutaneous branches of the VIII-XII IN in the area of the anterior-lateral regions of the abdominal wall. The connecting branches descend from the nodes of the thoracic section of the sympathetic trunk to the IN.