Alves, N (reprint author), Univ Talca, Fac Ciencias Salud, Dept Ciencias Basicas & Biomed, Ave Lircay S-N, Talca, ChileThe palmaris longus muscle (PLM) lies on the anterior region of the forearm, it is considered one of the most variable muscles in the human body, and its agenesis is the most frequent anatomic variation. The aim of this study was to evaluate the frequency of the PLM tendon in Chilean adults and also, to verify the agenesis symmetry according to sex. For this, we have analyzed the presence of the PLM tendon in 200 Chilean individuals, 114 female and 86 male. In this study, three different tests were used: Schaeffer's Test, Mishra's First Test and Thompson's Test. The obtained data were tabled and analyzed. It could be observed that 91% of the individuals had the PLM muscle tendon in at least one of the forearms and 80% in both forearms. The unilateral agenesis was found in 11% of the cases (5% on the right side and 6% on the left side) and bilateral agenesis was found in 9% of cases. When analyzing the frequency of the muscular tendon according to sex, we could observe that the PLM is more commonly found in men (82.56%) than in women (78.07%) (p > 0.05). Besides, we could observe that the agenesis is most frequent on the left side in women however, no significant statistical difference could be observed when the symmetry according to sex was analyzed (p > 0.05)

Alves, N.

Deana, N.F.

Ramirez, D.

International Journal of Morphology

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485INTRODUCTIONThe palmaris longus muscle (PLM) lies in the ante-rior region of the forearm, has its origin at the epicondylusmedialis of the humerus and inserts itself in the aponeurosispalmaris and into the distal part of the retinaculummusculorum flexorum. Its function is to tension theaponeurosis palmaris and it also works as an auxiliary flexor(Dângelo & Fattini,  1983).According to some authors, besides having a secondaryfunction, the loss of this muscle would not cause any significantloss of strength (Lippert, 1996). According to Sebastin & Lim(2006) the PLM experienced a filogenetic withdrawal withloss of function during human evolution and presented a gra-dual extinction. Besides, they claim that its absence wouldnot cause a functional loss of the wrist and hand.On the other hand, this muscle presents a great clinicalrelevance when used as a donator tendon in surgerytechniques as the reconstruction of the hand (Wehbé, 1992;Park et al., 2010) and the plastic surgery to repair neck andhead, cases in which we can obtain a satisfactory functionaland aesthetic reconstruction (Ueda et al., 2007; Ozeri et al.,2009).The PLM is considered one of the most variable musclesin the human body, its agenesis is considered the most frequentanatomical variation (Gray & Goss, 1977). Some authorssuggest that there is a relation between the prevalence of thePL agenesis and different ethnic groups (Reimann et al., 1944;Kapoor et al., 2008). The text-books report that the incidenceof the agenesis is of 14% (Moore & Agur, 1996), but a greatdiversity in the prevalence of this anatomic variation in differentpopulation has been reported. In a study with the Turkpopulation, Ceyhan & Mavt (1997) reported that 63.91% ofthe individuals presented PLM agenesis. However, Sebastin etal.  found 4.6% of agenesis in Chinese, and Gangata (2009),when evaluating black individuals from African origin, observedthat only 1.5% of the sample presented absence of PLM.In this study, our aim was to verify the frequency of thePLM tendon in adult Chilean individuals, and, also, observethe agenesis symmetry according to sex.Int. J. Morphol.,29(2):485-489, 2011.Study  of  Frequency  of  the  Palmaris  Longus  Musclein  Chilean  SubjectsEstudio  de  la  Frecuencia  del  Músculo  Palmar  Largo  en  Individuos  Chilenos*Nilton Alves; *Daysi Ramírez & **Naira Figueiredo DeanaALVES, N.; RAMÍREZ, D. & DEANA, N. F. Study of frequency of the palmaris longus muscle in Chilean subjects. Int. J. Morphol.,29(2):485-489, 2011.SUMMARY: The palmaris longus muscle (PLM) lies on the anterior region of the forearm, it is considered one of the mostvariable muscles in the human body, and its agenesis is the most frequent anatomic variation. The aim of this study was to evaluate thefrequency of the PLM tendon in Chilean adults and also, to verify the agenesis symmetry according to sex. For this, we have analyzed thepresence of the PLM tendon in 200 Chilean individuals, 114 female and 86 male. In this study, three different tests were used: Schaeffer’sTest, Mishra’s First Test and Thompson’s Test. The obtained data were tabled and analyzed. It could be observed that 91% of theindividuals had the PLM muscle tendon in at least one of the forearms and 80% in both forearms. The unilateral agenesis was found in11% of the cases (5% on the right side and 6% on the left side) and bilateral agenesis was found in 9% of cases. When analyzing thefrequency of the muscular tendon according to sex, we could observe that the PLM is more commonly found in men (82.56%) than inwomen (78.07%) (p>0.05). Besides, we could observe that the agenesis is most frequent on the left side in women however, no significantstatistical difference could be observed when the symmetry according to sex was analyzed (p>0.05).KEY WORDS: Palmaris longus muscle; Anatomic variation; Agenesis.*  Departamento de Ciencias Básicas y Biomédicas. Facultad de Ciencias de la Salud, Universidad de Talca.** Kinesióloga – Brasil486MATERIAL AND METHODIn this work were examined 200 young  Chilean adultof both sexes, leucoderm, 86 male and 114 female, with agevarying from 17 to 32 years old. The sample includedemployees and students from the Medicine and Odontologycourses from the Universidad de Talca, Chile.The following three tests were used to accomplishthe exams, on both of the forearms of all individuals, wherethe PLM tendons were visually observed and palpated byan examiner:1- Schaeffer’s Test: the examiner asks to the subject toaccomplish the movement of thumb opponency, followedby wrist flexion (Schaeffer, 1909) (Fig. 1).2. Mishra’s First Test: the examiner hyperextends themetacarpophalangeal joints and asks the patient to flexionthe wrist at the same time that he imposes some resistanceagainst the movement (Mishra, 2001) (Fig. 2).3. Thompson’s Test: The patient makes a fist and then aflexion movement of the wrist, after that, he/she put his/herthumb over the other fingers (Thompson, 1921) (Fig. 3).The PLM tendon was considered present in the ca-ses where it could be visualized and palpated in at least oneof the three tests, and it was considered absent when it couldnot be palpated in any of the tests. The obtained data wereanalyzed and tabled.RESULTSIn this study, forearms of 200 individuals wereanalyzed (114 women and 86 men), with average age of18.97 years old (DS ±2.06 years old). The average age ofwomen was 18.81 years old (DS ±1.94 years old) and theaverage for men was 19.17 years old (DS ±2.19 years old).Among the 200 subjects analyzed 182 (91%)presented the PLM tendon in at least one of the forearmsand 160 (80%) presented it in both forearms. The unilateralagenesis was observed in 11% (5% on the right side and 6%on the left side) of the cases and the bilateral absence wasreported in 9% of the cases. Therefore, the unilateral agenesiswas more common than the bilateral one, however, therewas no significant statistical difference (p>0.05) (Table I).The total agenesis (unilateral and bilateral) wasobserved with a higher frequency in women, that is, among114 women, 25 (21.93%) presented agenesis, on the otherhand, in the men sample, n=86, only 15 (17.44%) presentedabsence of the PLM tendon, however, there was nosignificant statistical difference (p>0.05). Among the 15 menwho presented agenesis, 6 (6.98%) were bilateral, and 9(10.46%) unilateral, 4 (4.65%) on the right side and 5(5.81%) on the left side. Among the sample of 25 womenwith agenesis, 12 (10.52%) presented bilateral agenesis, 13Fig. 1. Schaeffer's Test.Fig. 2. Mishra’s first Test.Fig. 3. Thompson’s Test.ALVES, N.; RAMIREZ, D. & DEANA, N. F. Study of frequency of the palmaris longus muscle in Chilean subjects. Int. J. Morphol., 29(2):485-489, 2011.487(11.40%) presented unilateral agenesis,being 6 (5.26%) on the right side and 7(6.14%) on the left side (Fig. 4).Regarding the tests to check thepresence of the PLM tendon, only theMishra’s first test did not present any kindof failure. It could be observed that in 20individuals (15 women and 5 men) theSchaeffer test did not show the musculartendon, however, it could be palpatedthrough the Mishra First Test and/orThompson Test. The same occurred withthe Thompson Test, in which 2 women and3 men did not show the presence of themuscular tendon, but it could be palpatedin the other two tests (Fig. 5).DISCUSSIONThe literature reports a widevariation in the prevalence of the agenesisin different ethnic groups. When Ceyhan& Mavt studied the Turk population theyfound high values of agenesis of the PLMtendon (63.91%). In a recent study, alsocarried out with the Turk, Kose et al.(2009) found 26.5% of prevalence of theagenesis, despite being a considerablevalue, it is highly inferior to the one fromthe first study and much closer to thevalues found in the Caucasian population(12.8% - 37.5%) (Reimann et al.;Thompson et al., 2001; Eric´ et al., 2010).Among the Nigerian, Kayode et al.(2008) found 31.25% of agenesis, a veryhigh percentage compared to the 6.7%found by Mbaka & Ejiwunmi (2009) and12.6% found by Enye et al. (2010) amongthe same population.In other ethnic groups lowerpercentages of agenesis could be observed,3.7% among the Amazon natives of theSouth America (Machado & DiDio, 1967),4.6% for the Chinese (Sebastin et al.), 1.5%for African black (Gangata), 11.5% in SouthAfricans miscegenated (Ndou et al., 2010)and 36.8% for the Bahraini population inthe Arabian Gulf (Sater et al., 2010).Fig. 4.  Palmaris longus muscle absence according sex (%).Fig. 5. Percentage of failed tests.Table I. Percentage of absence of the palmaris longus muscle.ALVES, N.; RAMIREZ, D. & DEANA, N. F. Study of frequency of the palmaris longus muscle in Chilean subjects. Int. J. Morphol., 29(2):485-489, 2011.Absent Bilateral Right Unilateral Left Unilateral TotalMen    6  (3%) 4  (2%) 5   (2.5%) 15 (7.5%)Women 12  (6%) 6   (3%) 7  (3.5%)  25 (12.5%)Total  18 (9%) 10  (5%)      12   (6%) 40  (20%)488Among the Indian population, Kapoor et al. found17.2% of total agenesis, a value close to the one found byAgarwal (2010), which was 20.2% in a recent study withIndians. In our study with Chileans, we found 20% of totalagenesis, a value similar to the one found by Agarwal amongthe Indian population.Several authors reported that the unilateral agenesis issignificantly more frequent than the bilateral (Thompson etal., 2001; Kayode et al.; Kapoor et al.; Mbaka & Ejiwunmi;Agarwal; Eric´ et al.). In our results we observed that the uni-lateral agenesis (11%) was higher than the bilateral (9%),although there was no significant statistical difference, suchcondition was also mentioned by Sebastin et al., Ndou et al.,and Enye et al. In the studies with the Turk populationaccomplished by Ceyhan & Mavt and Kose et al., thefrequency of the bilateral agenesis was highly superior to theunilateral.There is a great controversy in the literatureregarding the agenesis symmetry of the muscle related tosex. In our study the unilateral left agenesis in women wasmore commonly found, however, there was no significantstatistical difference. Thompson et al. (2001), Mbaka &Ejiwunmi and Ndou et al. also reported that the right andleft unilateral agenesis were statistically similar in bothsexes. Sater et al. reported that the muscle was absent moreoften on the left side than the right one.Regarding the prevalence according to sex,Thompson et al. (2001) reported that there was higherincidence of this agenesis in men. Kapoor et al. and Mbaka& Ejiwunmi found higher number of agenesis in men.However, there was no significant statistical difference. Koseet al. and Sater et al. claimed that there was a significantlyhigher number of agenesis in women than in men. In ourstudy there was a higher number of agenesis in women,however, there was no significant statistical difference, asclaimed by Ceyhan & Mavt and Sebastian et al.Regarding the tests accomplished in order to verifythe presence of the PLM tendon, the First Mishra’s test wasthe most accurate one. Both the Schaeffer and the Thompsontests presented some kind of failure. The Schaeffer Test wasalso imprecise in Kose et al., Mbaka & Ejiwunmi and Ndouet al. studies.Thus, we can conclude that the PLM is  frequent inthe Chilean population, even though agenesis wasobserved in some cases. Besides, the agenesis, whenpresent, was found mostly in women, and more on theleft side, however, when related, sex and agenesissymmetry, we could conclude that there was no significantstatistical difference.ALVES, N.; RAMÍREZ, D. & DEANA, N. F.  Estudio de la frecuencia del músculo palmar largo en individuos chilenos. Int. J.Morphol., 29(2):485-489, 2011.RESUMEN: El músculo palmar largo (MPL), ubicado en la región anterior del antebrazo, es considerado como uno de losmúsculos más variables del cuerpo humano, siendo su agenesia la variación anatómica más frecuentemente  señalada por los investiga-dores. El objetivo de este estudio fue investigar la frecuencia del tendón del músculo palmar largo en individuos chilenos y verificar lasimetría de la agenesia según el sexo. Para ello, analizamos la presencia del tendón del MPL en 200 individuos chilenos, 114 mujeres y86 hombres. Fueron utilizadas 3 pruebas: Prueba Schaeffer, Primera Prueba de Mishra y Prueba Thompson. Los datos obtenidos fueronregistrados y tabulados. Se observó que el 91% de los sujetos presentaron el tendón del MPL al menos en uno de los antebrazos, mientrasque un 80% lo presentaron en ambos antebrazos. Se observó aún que la agenesia unilateral estuvo presente en un 11% de los casos (5%en el lado derecho y 6% en el lado izquierdo), ya la  agenesia bilateral estuvo presente en 9%. Al analizar la presencia (unilateral ybilateral) del tendón del  PLM considerando el sexo, se  observó en el  82,56% de los hombres y en el 78,07% de las mujeres (p>0,05).Se observó que la ausencia del tendón del MPL era más frecuente en mujeres que en hombres, y en el lado izquierdo que en el derecho,no existiendo diferencias estadísticamente significativas (p>0,05).PALABRAS CLAVE: Músculo palmar largo; Variación anatómica; Agenesia.REFERENCESAgarwal, P. Absence of the palmaris longus tendon in Indianpopulation. Indian J. Orthop., 44(2):212-25, 2010.Ceyhan, O. & Mavt, A. Distribution of agenesis of palmarislongus muscle in 12 to 18 years old age groups. Indian J.Med. Sci., 51:156–60, 1997.Dângelo, J. G. & Fattini, C. A. Anatomia básica dos sistemasorgânicos: com a descrição dos ossos, junturas, múscu-los, vasos e nervos. 1ª ed. São Paulo, Atheneu, 1983.Eric, M.; Krivokuc´a, D.; Savovic´, S.; Leksan, I. & Vucinic´,N. Prevalence of the palmaris longus through clinicalALVES, N.; RAMIREZ, D. & DEANA, N. F. Study of frequency of the palmaris longus muscle in Chilean subjects. Int. J. Morphol., 29(2):485-489, 2011.489evaluation. Surg. Radiol. Anat., 32:357-61, 2010.Enye,  L. A.; Saalu, L. C.  & Osinubi, A. A. The prevalenceof agenesis of Palmaris longus muscle amongst studentsin two Lagos-Based Medical schools. Int. J. Morphol.,28(3):849-54, 2010.Gangata, H. The clinical surface anatomy anomalies of thepalmaris longus muscle in the Black African populationof Zimbabwe and a proposed new testing technique. Clin.Anat., 22:230–5, 2009.Gray, H. & Goss, C. M. Anatomia. 28ª ed. Rio de Janeiro,Guanabara Koogan, 1977.Kapoor, S. K.; Tiwari, A.; Kumar, A.; Bhatia, R.; Tantuway,V. & Kapoor, S. Clinical relevance of palmaris longusagenesis: common anatomical aberration. Anat. Sci. Int.,83(1):45-8, 2008.Kayode, A. O.; Olamide A. A.; Blessing, I. O. & Víctor O.U. Incidence of palmaris longus muscle absence inNigerian population. Int. J. Morphology, 26(2):305-8,2008.Kose, O.; Adanir, O.; Cirpar, M.; Kurklu, M. & Komurcu,M.. The prevalence of absence of the palmaris longus: astudy in Turkish population. Arch. Orthop. Trauma Surg.,129:609-11, 2009.Lippert, L. Cinesiologia Clínica para Fisioterapeutas,incluindo teste para auto-avaliação. 2 Ed: Rio de Janeiro,Ed. Revinter, 1996.Machado, A. B. & DiDio, L. J.  Frequency of the musculuspalmaris longus studied in vivo in some Amazon indians.Am. J. Phys. Anthropol., 27:11-20, 1967.Mbaka, G. O. & Ejiwunmi, A. B. Prevalence of palmarislongus absence – a study in the Yoruba population. UlsterMed. J., 78(2):90-3, 2009.Mishra, S. Alternative tests in demonstrating the presence ofthe palmaris longus. Indian J. Plastic Surg., 34:12, 2001.Moore, K. L. & Agur, A. M. R. Fundamentos de AnatomiaClínica. 1ª ed. Rio de Janeiro, Editora GuanabaraKoogan, 1996.Ndou, R.; Gangata, H.;  Mitchell, B.;  Ngcongo, T. &  Louw,G. The frequency of absence of palmaris longus in aSouth African population of mixed race. Clin. Anat.,23:437-42, 2010.Ozeri, E.; Sgarzani, R.; Negosanti, L.; Pizzigallo, A.; Cipriani,R. & Marchetti, C. “Hammock” reconstruction of full-thickness excised lower lip: a case report. Eur. J. Plast.Surg., 32:327-31, 2009.Park, I. J.; Kim, H. M.; Lee, S. U.; Lee, J. Y. & Jeong, C.Opponensplasty using palmaris longus tendon and flexorretinaculum pulley in patients with severe carpal tunnelsyndrome. Arch. Orthop. Trauma Surg., 130:829-34,2010.Reimann, A. F.; Daseler, B. H.; Anson, B. J. & Beaton, L. E.The Palmaris longus muscle and tendon. A study of 1600extremities. Anat. Rec., 89(4):495-505, 1944.Sater, M. S.; Dharap, A. S. & Abu-Hijleh, M. F.  Theprevalence of absence of the palmaris longus muscle inthe Bahraini population.  Clin. Anat., 23(8):956-61, 2010.Schaeffer, J. P.  On the variations of the palmaris longusmuscle. Anat. Rec., 3:275-8, 1909.Sebastin, S. J.  & Lim, A. Y. Clinical Assessment of Absenceof the Palmaris Longus and its Association With OtherAnatomical Anomalies-A Chinese Population Study. Ann.Acad. Med. Singapore, 35(4):249-53, 2006.Thompson, N. W.; Mockford, B. J. & Cran, G. W. Absence ofthe palmaris longus muscle: a population study.  UlsterMed. J., 70(1):22-4, 2001.Thompson, J. W.; McBatts, J. & Danforth, C. H. Hereditaryand racial variations in the musculus palmaris longus. Am.J. Phys. Anthrop., 4:205-18, 1921.Ueda, K.; Oba, S.; Okada, M.; Hara, M. & Zen, N. Eyelidreconstruction with a composite radial forearm palmarislongus tendon flap. J. Plast. Reconstr. Aesthet. Surg.,60:256-9, 2007.Wehbé, M. A. Tendon graft donor sites. J. Hand Surg. Am.,17(6):1130-2, 1992.Direccin para correspondencia:Dr. Nilton AlvesDepartamento de Ciencias Bsicas y Biomdicas. Facultadde Ciencias de la Salud, Universidad de Talca.Avenida Lircay s/n˚TalcaCHILE˚E-mail: niltonnalves@yahoo.com.br˚Recibido : 09-12-2010Aceptado: 28-02-2011ALVES, N.; RAMIREZ, D. & DEANA, N. F. Study of frequency of the palmaris longus muscle in Chilean subjects. Int. J. Morphol., 29(2):485-489, 2011.

Estudio  de  la  Frecuencia  del  Músculo  Palmar  Largo  en  Individuos  Chilenos

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Estudio de la Frecuencia del Músculo Palmar Largo en Individuos Chilenos

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