RESUMO
BACKGROUND: Fibrous bands (FB) are structures that cross the ulnar nerve (UN), distal to the cubital tunnel (CT). In surgical decompression of the UN in the elbow region, by endoscopy, these FB significantly impact UN visibility. The aim of the current study was to characterize the anatomical characteristics of these FB distal to the CT. METHODOLOGY: Eighteen formalinized upper limbs were dissected, nine right and nine left, within the Department of Anatomy of the Federal University of the State of Rio de Janeiro (UNIRIO). The dissections were performed with micro techniques, under a magnifying glass and a microscope. Classical UN exposure was established in the elbow region. RESULTS: Of the 18 upper limbs studied, 50% lacked any FB. When present, both the number and location of the FB varied, as near to the cubital tunnel as 3 cm past the UN's entrance into the tunnel, and as far away as almost 11 cm distal to it. Overall, there were no FB on either the left or right side in three cadavers (33.3%), FB on both the left and right side in three, and FB only on the left in three, meaning that FB were twice as common in left limbs (n = 6) as on the right (n = 3). CONCLUSIONS: Our study identified FB in 50% of the dissected limbs, all within 3-11 cm of the CT, though their number and location varied. Further studies are necessary to describe FB variations associated with compressive neuropathies of the UN distal to the CT.