Tendon variations of ED and APL muscles were observed in a 65-year-old male formalin-fixed cadaver at the Gulhane Military Medical Academy Anatomy Dissection

Muscle and tendon variations in hand and wrist are not rare; thus their type must be well known in practicing hand surgery. Abductor pollicis longus (APL) and extensor digitorum (ED) are known to exhibit different variations with respect to their attachments. Various studies have reported splitting of the APL and ED [1-8]. The ED has one origin and a common muscle belly that splits into three or four sections that continue as tendons to the extensor hood on the dorsum of the fingers. The anatomic variations, arrangements and prevalence of these tendons have been documented in clinical and anatomic studies [9,10]. The APL originates from the radius, interosseous membrane and ulna on the dorsum of the forearm. Its tendon travels with the extensor pollicis brevis in the first dorsal compartment. Its primary insertion is into the radial side of the base of the first metacarpal bone. There are multiple additional slips of insertion including the trapezium, dorsal aponeurosis, thenar musculature (particularly abductor pollicis brevis) and flexor retinaculum. It abducts not only the thumb, but also the wrist, and is innervated by the posterior interosseous nerve [10]. The hand, with respect to its function is one of the special organs of human body, is the most frequently injured part of the body, and complete knowledge is extremely important in hand examination, treatment and reconstruction, including orthopedic procedures as tendon transfers. Anatomical variations of the extrinsic extensor tendons are frequent and knowledge is important when assessing the traumatized or diseased hand.