The Dorsal Aponeurosis of the Thumb.

PURPOSE: To evaluate the thumb dorsal aponeurosis anatomy. Consideration of structural differences between the fingers and thumb will provide an improved clinical understanding of the thumb dorsal aponeurosis anatomy.

METHODS: Ten fresh cadaver hands from 5 patients with an average age of 31.6 (range, 22-41) years were dissected. The thenar muscles were identified and insertion sites were documented. The fibers of the dorsal aponeurosis and contributions were identified.

RESULTS: The flexor pollicis brevis superficial head contributed to the radial fibers of the dorsal aponeurosis in 8 specimens and contributed to the deep head in 1 specimen. The abductor pollicis brevis provided fibers to the radial dorsal aponeurosis in all 10 specimens. The oblique and transverse heads of the adductor pollicis contributed to the ulnar dorsal aponeurosis in 8 and 9 hands, respectively. The fibers of the intrinsic apparatus were composed of 3 major types: transverse, oblique, and long.

CONCLUSIONS: This investigation provides a detailed anatomic study of the dorsal aponeurosis of the thumb with observation of both intrinsic and extrinsic contributions.

CLINICAL RELEVANCE: Understanding the anatomy of the dorsal aponeurosis of the thumb remains important not only for evaluation of the classic Stener lesion, but also for the appropriate treatment of deformity, contracture, and neuromuscular disorders involving the thumb.