The visceral structures of the head, neck, upper limb, and viscera of the thoracic cavity are innervated by sympathetic preganglionic neurons of the upper thoracic centre specifically by segments T2 to T5. Hyperhidrosis is defined as excessive production of eccrine sweat. The objective of this work is to describe the arrangement, variations, and patterns of conformation of the thoracic sympathetic chain and its implications in pathological focal hyperhidrosis. A descriptive, observational, and morphometric study of the sympathetic innervation of the thoracic cavity was carried out. For this, 60 10 % formalin-fixed cadaveric dissections were used, from the Third Chair of Anatomy, School of Medicine, University of Buenos Aires, Argentina, in a period from March 2022 to May 2023. Regarding the variations of the Kuntz nerve described in 24 cadavers, the classification of Chung et al. (2002) was applied for its distribution: (2002):Type A, connection of the T2 to T1 nerve was found in 41.67 %; type B, connection of the T2 nerve to the anterior branch of the intercostal nerve in 8.33 %; type C, connection of the T2 nerve to the communicating branch between the T1 nerve and the stellate ganglion in 33.33 % and type D, bifurcated connection of the T2 nerve to the T1 nerve and intercostal nerve in 16.67 %. The nervous structure referred as the Kuntz nerve should be replaced with an anatomical term that complies with the Regular Anatomical Terminology (RA term rules). It is essential to have a thorough understanding and description of the variations and patterns of the paravertebral sympathetic chain in order to effectively diagnose and treat hyperhidrosis. Understanding these variations is crucial when considering surgical treatment options.

KEY WORDS: Autonomic innervation; Kuntz's nerve; Hyperhidrosis; Regular Anatomical Terminology.