An unusual digital neural loop in a cadaver with bilateral high branching median nerves - case report

Digital neural loops are present in the palms of most individuals. They can arise within the common palmar digital nerves (CPDNs) or proper palmar digital nerves (PPDNs). Typically, common palmar digital arteries (CPDAs) pass through digital neural loops, however there are reports of loops forming around the superficial palmar arch or proper palmar digital arteries (PPDAs). We describe an unusual digital neural loop that involved both a CPDN and a PPDN. To our knowledge, this is the first documented case of a digital neural loop of this type and therefore anatomists and surgeons may benefit from an awareness of its existence. A modification to a current classification system for digital neural loops is presented to include this novel loop. Interestingly, the cadaver documented in this report featured a high division of the median nerve in each forearm. On both sides, the ulnar component of the bifid median nerve followed an intramuscular course in which it pierced the flexor digitorum superficialis and then continued into the palm as the 3rd CPDN. A brief review of the literature is provided for both digital neural loops and the high division of the median nerve variant. Documented muscle associations noteworthy to the bifid median nerve are discussed. Developmental connections, if any, that exist between the unique digital neural loop and the high division of the median nerve are not speculated upon.