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Morphometric study and occurrence of the palmaris longus muscle in human fetuses

MOJ Anatomy & Physiology
José Aderval Aragão,1,4 Julio Cezar de Oliveira Filho,2 Otávio Vinicius Nascimento de Oliveira,2 Layla Raíssa Dantas Souza,2 Bianca Holz Vieira,2 Iapunira Catarina Sant’Anna Aragão,3 Felipe Matheus Sant’Anna Aragão,3 Francisco Prado Reis4

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Introduction: The palmaris longus muscle has a short belly and a long tendon, it is located in the superficial layer of the anterior compartment of the forearm and usually has insertions in the medial humeral epicondyle and palmar aponeurosis. As it is an accessory muscle in wrist flexion, its absence does not cause functional impairment and its tendon is used as a graft in many surgical procedures. This study aimed to determine the occurrence of the palmaris longus muscle and its musculotendinous relations.
Methods: 20 forearms of 10 fetuses were dissected, with ages ranging from 19.6 to 37.8 weeks of gestation, belonging to the anatomy laboratory of the Federal University of Sergipe. The belly and tendon length of the palmaris longus muscle were measured using a 0.01mm precision digital caliper.
Results: The palmaris longus muscle was present in all cases. The length of the palmaris longus muscle (PLM) was slightly longer on the right side, with its muscular belly being larger in the left dimidium and its tendon in the right. The relation between the length of the PLM and its tendon was slightly higher in the left dimidium; and the relation between the length of the MPL and its belly, as well as tendon/belly were bigger in the right dimidium.
Conclusion: The knowledge about the anatomy of the PLM may assist in the diagnosis of Carpal Tunnel Syndrome and Dupuytren's disease, as well as being useful to surgeons regarding tendon measurements to be used as grafts.


palmaris longus muscle, tendon measurements, carpi ulnaris muscle, humerus