title: Morphometric and statistical analysis of the palmaris longus muscle in human and non-human primates.
abstract: The palmaris longus is considered a phylogenetic degenerate metacarpophalangeal joint flexor muscle in humans, a small vestigial forearm muscle; it is the most variable muscle in humans, showing variation in position, duplication, slips and could be reverted. It is frequently studied in papers about human anatomical variations in cadavers and in vivo, its variation has importance in medical clinic, surgery, radiological analysis, in studies about high-performance athletes, in genetics and anthropologic studies. Most studies about palmaris longus in humans are associated to frequency or case studies, but comparative anatomy in primates and comparative morphometry were not found in scientific literature. Comparative anatomy associated to morphometry of palmaris longus could explain the degeneration observed in this muscle in two of three of the great apes. Hypothetically, the comparison of the relative length of tendons and belly could indicate the pathway of the degeneration of this muscle, that is, the degeneration could be associated to increased tendon length and decreased belly from more primitive primates to those most derivate, that is, great apes to modern humans. In conclusion, in primates, the tendon of the palmaris longus increase from Lemuriformes to modern humans, that is, from arboreal to terrestrial primates and the muscle became weaker and tending to be missing.
authors.affiliation: Department of Anatomy, Howard University College of Medicine, 520 W Street NW, Numa Adams Building, Washington, DC 20059, USA ; Laboratory of Primate Anthropology, Biochemistry, Neurosciences and Behavior, Federal University of Tocantins, NS 15 Avenue, Block 109 Norte, Plano Diretor Norte, 77001-090 Palmas, TO, Brazil ; Graduate School of Animal Biology, Institute of Biology, University of Brasilia, Darcy Ribeiro Campus, 70910-900 Brasília, DF, Brazil ; Department of Physiology, Laboratory of Neuroscience and Behavior, University of Brasilia, Darcy Ribeiro Campus, 70910-900 Brasília, DF, Brazil.
authors.forename: Roqueline A G M F
authors.initials: RA
authors.lastname: Aversi-Ferreira
authors.affiliation: System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-1494, Japan.
authors.forename: Rafael Vieira
authors.initials: RV
authors.lastname: Bretas
authors.affiliation: Graduate School of Animal Biology, Institute of Biology, University of Brasilia, Darcy Ribeiro Campus, 70910-900 Brasília, DF, Brazil ; Department of Physiology, Laboratory of Neuroscience and Behavior, University of Brasilia, Darcy Ribeiro Campus, 70910-900 Brasília, DF, Brazil.
authors.forename: Rafael Souto
authors.initials: RS
authors.lastname: Maior
authors.affiliation: System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-1494, Japan.
authors.forename: Munkhzul
authors.initials: M
authors.lastname: Davaasuren
authors.affiliation: Federal University of Rondonia, RO, Brazil.
authors.forename: Carlos Alberto
authors.initials: CA
authors.lastname: Paraguassú-Chaves
authors.affiliation: System Emotional Science, Graduate School of Medicine and Pharmaceutical Sciences, University of Toyama, Toyama 930-1494, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Nishijo
authors.affiliation: Department of Anatomy, Howard University College of Medicine, 520 W Street NW, Numa Adams Building, Washington, DC 20059, USA ; Laboratory of Primate Anthropology, Biochemistry, Neurosciences and Behavior, Federal University of Tocantins, NS 15 Avenue, Block 109 Norte, Plano Diretor Norte, 77001-090 Palmas, TO, Brazil.
authors.forename: Tales Alexandre
authors.initials: TA
authors.lastname: Aversi-Ferreira
mesh_terms: D000818:Animals; D001029:Aotus trivirgatus; D053819:Atelinae; D001938:Brazil; D002102:Cadaver; D002144:Callithrix; D003627:Data Interpretation, Statistical; D005260:Female; D005542:Forearm / Q000033:anatomy & histology; D006801:Humans; D007900:Lemur; D008251:Macaca; D008297:Male; D008953:Models, Anatomic; D018482:Muscle, Skeletal / Q000033:anatomy & histology*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013045:Species Specificity; D011443:Strepsirhini