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Background: Accessory belly of the hypothenar muscles in hand have been involved in vascular and nerve compression. The most common variable muscle is abductor digiti minimi (AbDM). The purpose of this study is to investigate the anomaly of AbDM that is called AAbDM.
Objective: To study quantity and describe the AAbDM in Thai people.
Study design: A descriptive study
Setting: The study was carried out at the Department of Anatomy, Faculty of Medicine, Khon Kaen University, Thailand.
Subject: The study included six hundred hands from 300 formalin-embalmed cadavers, 25-82 years of age.
Methods: 1. Study the number of hands which was found AAbDM.
2. Describe the origin, insertion and nerve supply of each muscle.
Results: Only one hand from 600 hands was seen AAbDM. It was found in the right hand of Thai male cadaver aged 55 years. The origin of this muscle arises from pisiform bone, splitting from AbDM then forms aponeurosis and inserts into the base of the proximal phalanx of the fifth finger. The innervation is by the deep branch of ulnar nerve.
Conclusion: Only one right hand from 600 hands was found AAbDM. The origin, insertion and nerve supply of this muscle were described.
Key Words: Abductor digiti minimi muscle, Accessory abductor digiti minimi muscle,