IJAR.2025.122
Type of Article: Original Research
Volume 13; Issue 2 (June 2025)
Page No.: 9197-9203
DOI: https://dx.doi.org/10.16965/ijar.2025.122
Dorsal Digital Expansion Of Thumb – A Cadaveric Study and Its Clinical Significance
Jyothi S.R *1, Chaithra Rao B.R 2, Vasudha T.K 3.
*1 Assistant Professor, Department of Anatomy, Chikkaballapur Institute of Medical Sciences, Chikkaballapura, Karnataka, India. ORCiD: https://orcid.org/0009-0003-0706-893X
2 Associate Professor, Department of Anatomy, Chikkaballapur Institute of Medical Sciences, Chikkaballapura, , Karnataka, India. ORCiD: https://orcid.org/0009-0004-9584-232X
3 Professor, Department of Anatomy, Subbaiah Institute of Medical Sciences, Purale, Shivamogga, Karnataka, India. ORCiD: https://orcid.org/0009-0008-7531-4035
Corresponding Author: Dr. Jyothi S.R, Assistant Professor, Department of Anatomy, Chikkaballapur Institute of Medical Sciences, Chikkaballapura, Karnataka, India.
E-Mail: jyothisr39@gmail.com,9739724658
ABSTRACT
Background: Human hand is a prehensile organ & is endowed with grasping, precision movements for skilled work. Broad representation of thumb in the brain reflects the functional importance & complexity of movements of thumb. A succession of activity occurs among the extensor tendons & the thenar muscles during opposition. Dorsal digital expansion has been reported in our study & contribution made by muscular elements which go into its formation has been described. Many authors are not in consensus regarding its anatomy, hence the study was undertaken.
Methodology: An observational descriptive study, using 50 free upper limbs, in the department of Anatomy was carried out. Dissection was performed following instructions from the standard practical manual. Observations were described, photographed & tabulated.
Results: The DDE (Dorsal Digital Expansion) of thumb, a pearly white translucent triangular expansion on dorsum of its proximal phalanx, is the tendinous fibers of the EPL (Extensor Pollicis Longus) & EPB (Extensor Pollicis Brevis) was found in all specimens. Medial margin being more prominent, in addition to EPL & EPB received fibers from Adductor pollicis & first palmar interossei (if present). The lateral margin received contribution from APB (Abductor Pollicis Brevis) & FPB (Flexor Pollicis Brevis). The percentage of each tendon contribution towards DDE has been tabulated & variations in the insertion of extensor tendons to the phalanges are also discussed.
Conclusion: Human thumb plays a crucial role in the smooth functioning of hand. The knowledge of DDE adds to analyze the biomechanics of thumb & in the management of de Queverain’s Tenosynovitis (DQT). Multiple tendons may attribute to disturbance in joint movements.
Key words: Dorsal digital expansion, Extensor pollicis longus, Extensor pollicis brevis, Adductor pollicis, Abductor pollicis brevis, Flexor pollicis brevis, de Queverain’s Tenosynovitis, proximal phalanx, distal phalanx.
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