Anatomical variations of the hand extensors

Abstract

This study was performed to investigate the anatomy and variations of the humanextensor tendons of the fingers and their intertendinous connections. Ninetyfive upper limbs of adult cadavers were dissected. The variations in the extensortendons of the fingers, both proximal and distal to the extensor retinaculum, andtheir mode of insertion were observed. Also, the intertendinous connections wereexplored and the obtained data were analysed. The extensor pollicis longus andbrevis tendons were found to be single, doubled or, rarely, absent. Their insertioncould be traced to either the proximal phalanx, or through the extensor expansionto both phalanges, or rarely to the distal phalanx of thumb. The extensor indicishad a single tendon in all specimens. In the majority of specimens, extensor digitorumhad no independent slip to the little finger; it gave off a single tendonto the index, double tendons to the middle finger and triple tendons to the ringfinger. Extensor digiti minimi muscle often had double or triple tendons distal tothe extensor retinaculum. Three types of juncturae tendinum (JT) were identifiedbetween the tendons of extensor digitorum in the 2nd, 3rd and 4th intermetacarpalspaces (IMS) of hands. Types 1 and 2 JT were seen in the three IMS. Type 3 JTwas the most frequently identified of all juncturae and was always absent in the2nd IMS. The percentages of the present data were compared with other researchers’data.