Aberrant Volar Wrist Musculature: Cadaveric-Clinical Correlation and Implications for Median and Ulnar Nerve Compression Syndromes

Introduction: Compression syndromes of the wrist are a group of pathologies that cause compressive neuropathy of the median or ulnar nerves; these can be idiopathic, mechanical, or neoplastic in nature. Aberrant volar wrist muscles are uncommon and inconsistently recognized causes of median and ulnar neuropathies at the wrist. These anatomical variants can be encountered intraoperatively, during preoperative imaging, and/or during cadaveric dissections. Here, we review the aberrant muscles relevant to compressive syndromes at the wrist and report a series of clinical and cadaveric cases. Methods: We retrospectively reviewed carpal tunnel and Guyon’s canal decompression procedures at an academic center and report two cases of aberrant volar muscles identified intraoperatively. Two cadaveric dissections demonstrating aberrant muscles were also reviewed. Surgical anatomy, spatial relationships to the nerves, and compressive potential were analyzed and reviewed. Results: Variants compressing the median nerve included reversed palmaris longus, palmaris profundus, and an unreported radial-origin muscle (“reversed radialis”). A variant compressing the ulnar nerve, an accessory abductor digiti minimi forming the roof of Guyon’s canal, is also described. In operative cases, aberrant musculature directly compressed or obscured the nerves, and resection was required for adequate decompression. Conclusion: Aberrant volar wrist muscles may contribute to persistent or recurrent compression syndromes and complicate traditional approaches. Awareness of these variants is essential for operative planning, intraoperative recognition, and appropriate thorough decompression of the nerves. If they are found incidentally during routine imaging, they need not be resected unless symptomatic.