Das Ligamentum metacarpale pollicis* - Topographie und funktionelle Deutung eines bisher unbekannten Faserzuges am Daumen und seine Lagebeziehungen zum M. interosseus internus -

During cadaver dissections of the thenar muscles of 81 human hands, we found a distinct ligament at the palmar side of the first metacarpal in 58% ([symbol: see text] 47 hands). This not previously described ligament crosses the princeps pollicis artery regularly. The ligament arises from the base of the first metacarpal bone in 83%. Sometimes (in 15%) it arises from the trapezium or from the middle portion of the first metacarpal bone in one case. The primary insertion of this ligament is the ulnar sesamoid. We have named these fibres "metacarpal ligament of the thumb". It could be classified into five different types. We think that this ligament is helpful in the stabilisation of the ulnar sesamoid. Besides it fixes the princeps pollicis artery to the metacarpal bone and therefore it is possible that it could compress the artery. Maybe the "metacarpal ligament of the thumb" is a rudiment of the interosseous muscles of the thumb or of the deep head of the flexor pollicis brevis muscle or of the oblique head of the adductor pollicis muscle. There is a very close topographic relationship between this ligament and the "internal interosseous muscle" of the thumb which was described by Schmidt and Lanz (1992) and which was mentioned by Henle (1858), who named it "M. interosseus volaris primus" for the first time. We could isolate this muscle in 69%.