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Purpose: The main objective of this study was to identify anatomical differences between men and women in the absolute and relative size of the carpal tunnel (CT), its inner structures, and related external anatomical structures in order to shed light on the higher prevalence of CT syndrome (CTS) in women., Basic Procedures: We have dissected the forearms and hands of ten men and ten women and compared the cross-sectional area (CSA) of the CT between the two sexes. The size of the CT relative to the tendons passing through it, the median nerve (MN), and to hand and wrist size was also compared between men and women., Main Findings: The absolute CSAs of the CT and other parameters were larger in men than in women. The CSA of the CT relative to the length of the capitate bone was also larger in men. However, no significant differences were observed between men and women in the size of the CT relative to its inner structures., Principal Conclusions: The size of the inner structures of the CT are in proportion to that of the CT itself in both sexes. These findings suggest that the etiology of CTS seems to be primarily related to workload and personal traits., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. Conflicts of interest The authors declare that they have no conflicts of interest., (Copyright © 2022 Elsevier GmbH. All rights reserved.)

ABSTRACT To explore the anatomical factors potentially involved in the high incidence of carpal tunnel syndrome in humans, we have quantified the anatomical variations of the carpal tunnel and its inner structures in humans, non‐hominoid primates (monkeys), and hominoid primates (apes). In specimens of six humans, eight monkeys, and three apes, we assessed the size of the carpal tunnel, the tendons of the digit flexor muscles, and the median nerve. We compared the size of the carpal tunnel normalized by the wrist size, and the size of the median nerve and the tendons of the digit flexors normalized by the size of the carpal tunnel. Differences between humans and monkeys were calculated using the T test or Mann–Whitney U test, as appropriate. Data on the apes were not included in the statistical analyses due to the small sample size. The normalized size of the carpal tunnel was similar in all specimens. The normalized size of the tendons of the digit flexors was smaller in humans, while that of the median nerve was significantly larger. The median nerve was also larger in apes than in monkeys. The relatively larger median nerve observed in humans could suggest a greater vulnerability of the nerve to compression, which could predispose humans to carpal tunnel syndrome. However, the tendons of the digit flexor muscles were smaller in humans, and moreover, the proportional size of the median nerve was similar in apes, leading us to suggest that the factors predisposing humans to carpal tunnel syndrome must be sought beyond anatomical features and may be more closely related to functional or personal parameters. [ABSTRACT FROM AUTHOR]