Neural entrapments associated with musculoskeletal anatomical variations of the upper limb: Literature review

Introduction: In the upper there are different neural entrapment sites that can be associated with neighboring structures which in turn can mimic other neural entrapments syndromes. The objective of this study was to review the literature concerning neuromusculoskeletal anatomical variations in the upper limb and their possible clinical correlations with certain pathologies or syndromes. Methods: A systematic literature search over different databases was used to examine the relationship between anatomical variations of neuromusculoskeletal structures and pathologies in the upper limb, using the search strategy proposed by the Cochrane Handbook for Systematic Reviews of Interventions. Results: Analysis of the full text studies after the exclusion criteria had been applied showed that anatomical variations in the upper limb correlated in one third of the studies to nerve entrapment, such compressions frequently being attributable to some type of accessory muscle or variation in its insertion site. This demonstrates the importance of knowing the normal anatomy in order to investigate these structures and their possible variations, thus avoiding a non-specific differential diagnosis. Conclusions: This literature review does not address a single type of anatomical variation but gives guidelines for considering different structures of the upper limb with anatomical variations that could predispose to some type of upper limb neural entrapment.