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Morphometric and statistical analysis of the palmaris longus muscle in human and non-human primates.

Aversi-Ferreira RA, Bretas RV, Maior RS, Davaasuren M, Paraguassú-Chaves CA, Nishijo H, Aversi-Ferreira TA - Biomed Res Int (2014)

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

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.

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.

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Graph showing the mean line relative to the palmaris longus/tendon length of primate groups.
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fig2: Graph showing the mean line relative to the palmaris longus/tendon length of primate groups.

Mentions: Regarding the type of fiber arrangement in the belly, the palmaris longus tendon presented an aspect similar to pennate in all Lemuriformes and New World primates (Figure 1), but fusiform to Macaca fuscata (unique exemplar of Old World primates) and to apes (Pongo sp. and Pan sp.) and modern humans. The average palmaris longus/tendon length showed significant differences between species studied in this work (Table 1, Figure 2). Shorter tendons were observed in Lemuriformes and longer in modern humans (P < 0.05, Figure 2).


Morphometric and statistical analysis of the palmaris longus muscle in human and non-human primates.

Aversi-Ferreira RA, Bretas RV, Maior RS, Davaasuren M, Paraguassú-Chaves CA, Nishijo H, Aversi-Ferreira TA - Biomed Res Int (2014)

Graph showing the mean line relative to the palmaris longus/tendon length of primate groups.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4016873&req=5

fig2: Graph showing the mean line relative to the palmaris longus/tendon length of primate groups.
Mentions: Regarding the type of fiber arrangement in the belly, the palmaris longus tendon presented an aspect similar to pennate in all Lemuriformes and New World primates (Figure 1), but fusiform to Macaca fuscata (unique exemplar of Old World primates) and to apes (Pongo sp. and Pan sp.) and modern humans. The average palmaris longus/tendon length showed significant differences between species studied in this work (Table 1, Figure 2). Shorter tendons were observed in Lemuriformes and longer in modern humans (P < 0.05, Figure 2).

Bottom Line: 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.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.

View Article: PubMed Central - PubMed

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.

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.

Show MeSH
Related in: MedlinePlus