Variant extensor muscles on the dorsum of the hand

Usually the dorsal surface of the hand is devoid of muscle bellies, it only contains the tendons of the extensor muscles of the hand. Between the dorsal carpal ligament and the carpal bones six compartments are formed for the passage of tendons. Found on the dorsum of the hand are the tendons of the extensor pollicis longus, extensor digitorum communis, extensor indicis (extensor indicis proprius), and the extensor digiti minimi (extensor digiti quinti proprius). However, the existence of variant muscles on the dorsum of the hand has been documented in numerous publications. Some of these variant muscles include; the accessory abductor digiti minimi, found in 24 % of all wrists; the extensor digitorum brevis manus found in 1-3% of the population [1], and the extensor medii proprius which has an incidence between 0.8% and 10.4% [2].