Anatomical variations of the hand extensors

Abstract

This study was performed to investigate the anatomy and variations of the human extensor tendons of the fingers and their intertendinous connections. Ninetyfive upper limbs of adult cadavers were dissected. The variations in the extensor tendons of the fingers, both proximal and distal to the extensor retinaculum, and their mode of insertion were observed. Also, the intertendinous connections were explored and the obtained data were analysed. The extensor pollicis longus and brevis tendons were found to be single, doubled or, rarely, absent. Their insertion could be traced to either the proximal phalanx, or through the extensor expansion to both phalanges, or rarely to the distal phalanx of thumb. The extensor indicis had a single tendon in all specimens. In the majority of specimens, extensor digitorum had no independent slip to the little finger; it gave off a single tendon to the index, double tendons to the middle finger and triple tendons to the ring finger. Extensor digiti minimi muscle often had double or triple tendons distal to the extensor retinaculum. Three types of juncturae tendinum (JT) were identified between the tendons of extensor digitorum in the 2nd, 3rd and 4th intermetacarpal spaces (IMS) of hands. Types 1 and 2 JT were seen in the three IMS. Type 3 JT was the most frequently identified of all juncturae and was always absent in the 2nd IMS. The percentages of the present data were compared with other researchers'data.