Morphological Variants of the Abductor Pollicis Longus and Extensor Pollicis Brevis Tendons. A Cadaveric Study

Background. The goal of the present research was to study the morphological variants of the abductor pollicis longus (APL) and extensor pollicis brevis (EPB) tendons and their distal insertions in the hand. Methods. An aggregate of 115 embalmed cadaveric upper limbs were utilized for this descriptive cross-sectional study. The morphological variants of the APL tendon were divided into 4 categories, one (type 1), two (type 2), three (type 3) and more than three tendons (type 4). The variations of tendons of EPB were divided into 3 types, one tendon (type 1), two tendons (type 2) and the absence of muscle (type 0). Results. It was observed that, only 22 upper limbs (19.1%) had single tendon of APL (type 1). The double tendon of APL was observed in 73 (63.5%) specimens (type 2). In 19 (16.5%) cases, there were three tendons of the APL (type 3). In one of the upper limbs (0.9%), there were six tendons of the APL (type 4). The present study also observed that, in 112 (97.4%) cases, EPB was having a single tendon (type 1) and in one specimen (0.9%), it had two tendons (type 2). The EPB muscle was absent in 2 (1.7%) cases (type 0). Conclusions. The morphological knowledge about the APL and EPB tendons are of importance in the plastic and reconstructive hand surgeries. The present study observed that, the accessory tendons of APL have higher frequency than the expected.