Morphologic Aspects of Abductor digiti minimi Muscle in the Hand

Abstract

SUMMARY:The Abductor digiti minimi muscle, and the other hypotenar muscles, frequently presents anatomical variations. According to literature, this muscle can be composed by one, two or three muscular beams, as well as it can present accessory muscular beams.In dissecations of 40 formolized hands, we objectified to study the morphology and variations of the Abductor digiti minimi muscle. The muscle presented two muscular beams in 82,5 %, three beams in 15% and only 1 beam in 2,5 % of the cases. In none of cases accessory muscular beams were observed.When compared with literature, are observed statistics difference in some studied aspects. The results found in the research allow to affirm that the Abductor digiti minimi muscle is formed by two muscular beams in the biggest part of the cases. The division of the muscle in three muscular beams is common of being found. 374 MATERIAL AND METHODWere dissected forty specimens of right and left hands obtained from formol-fixed adult cadavers, of varied ethnic groups and age bands. The dissecations were realized with the aid of a microscope to an increase of 6x. RESULTSThe Abductor digiti minimi muscle, in 33 cases, was composed by two muscular beams, a lateral and a medial one.The two beams were well-defined, separated by Areolar connective tissue, and fused togheter in their proximal extremity, without any comunication after their proximal insertion and each one had its proper tendon of distal insertion. Fig. 1.In 6 cases, the Abductor digiti minimi muscle was composed by three muscular beams. The two bigger portions correspond to the ones decribed previously; the third portion was thin and short in comparison to the other beams, was located deeply to the medial portion, over the opponent digiti minimi muscle. Fig. 2.In 1 case, the abductor digiti minimi muscle was formed by only one muscular beam. 375 DISCUSSIONAnatomical literature is controversial when affirming by how many muscular beams the Abductor digiti minimi muscle in the man is composed. Analyzing literatures cited in the introduction of this article, in accordance with the different authors, we perceive that the muscle can be composed by one, two or three muscular beams. When comparing these authors with our results, we perceive that a standard was more found: the muscle was divided in two muscular beams in 82,5% of the cases. With these results, we can disagree with the authors who cite the Abductor digiti minimi muscle formed by only one muscular beam.Between the searched authors, only Neto et al. confer a nomenclature to these muscular beams, calling medial the deeper muscular beam, located over the opponent digiti minimi muscle, and lateral the other muscular beam, more superficial, responsible for the arch in the ulnar edge of the hand. This nomenclature is considered by us adjusted. Not only to the cases where the muscle has only two, but also to the cases where it presents three muscular beams, when we perceive that the two bigger muscular beams correspond to both above cited.Also we agree to Wil...