Prevalence of the palmaris longus and its impact on grip strength in elite gymnasts and non-athletes / Prevalencia del músculo palmar largo y el impacto en la fuerza de agarre en gimnastas de elite y no atletas

In elite athletes, the palmaris longus (PL) presence has a potential contribution to hand strength, smaller reaction time, better shooting speed and power. The aim of this study was to investigate the prevalence of PL in elite competitive artistic gymnasts and its impact on grip strength compared to a control group of moderately active non-athletes. This prospective study included 370 subjects divided in two groups (170 elite artistic gymnasts and 200 moderately active non-athletes, students of medicine). The study consisted of two clinical sets of examination: a search for the clinical presence of PL was initially conducted followed by the assessment of maximal grip strength. Standard and six additional tests were performed to confirm PL tendon absence. Maximal grip strength was measured bilaterally with an electronic hand dynamometer. Bilateral absence was more common than unilateral, predominately noted on left side in both study groups. Unilateral PL absence was correlated to decreased grip strength in students, while the opposite was found in gymnasts. The mean value of grip strength in some age groups was higher on the side where the PL was absent. The results of our study show that the presence of the PL doesn`t affect the hand grip strength in gymnasts. Due to the low incidence of unilateral PL absence, further large-sampled research is warranted to assess PL contribution to hand grip strength and to other hand functions that could be of significant importance for athletes and non-athletes.

La presencia del músculo palmar largo (MPL) en atletas de élite tiene el potencial de aportar mayor fuerza a la mano, un tiempo de reacción menor, mejor velocidad de tiro y potencia. El objetivo de este estudio fue investigar la prevalencia de MPL en las gimnastas artísticas competitivas de élite y su impacto en la fuerza de agarre en comparación con un grupo control de no atletas moderadamente activos. El estudio incluyó 370 sujetos divididos en dos grupos (170 gimnastas artísticas de élite y 200 no atletas moderadamente activos, estudiantes de medicina). El estudio consistió en dos series clínicas de examen: inicialmente se realizó una búsqueda de la presencia clínica de MPL, seguido de la evaluación de la fuerza máxima de agarre. Se realizaron pruebas estándar y seis pruebas adicionales para confirmar la ausencia del tendón del MPL. La máxima fuerza de agarre se midió bilateralmente con un dinamómetro de mano electrónico. La ausencia bilateral fue más común que unilateral, predominantemente observada en el lado izquierdo en ambos grupos de estudio. La ausencia unilateral de MPL se correlacionó con una menor fuerza de agarre en los estudiantes, mientras que en gimnastas se encontró lo contrario. El valor medio de la fuerza de agarre en algunos grupos de edad fue mayor en el lado donde el MPL estaba ausente. Los resultados de nuestro estudio muestran que la presencia de MPL no afecta la fuerza de agarre de la mano en gimnastas. Debido a la baja incidencia de ausencia unilateral de MPL, se justifica una investigación adicional de gran tamaño para evaluar la contribución de MPL a la fuerza de agarre de la mano y otras funciones de la mano que podrían ser de gran importancia para los atletas y no atletas.

A rare variation of intrinsic and extrinsic hand muscles represented by a bi-ventered first lumbrical extending into the carpal tunnel combined with bilateral fifth superficial flexor digitorum tendon regression.

A rare unilateral variation of the first left lumbrical muscle was discovered in a female Caucasian cadaver dissected during a first year anatomy course at the Paracelsus Medical University - Nuremberg, Germany. The muscle possessed two venters with the first originating near the medial epicondyle of the humerus together with the intramuscular tendon of the superficial flexor digitorum tendon, and the second presenting as a regular first lumbrical muscle with radial palmar origin from first tendon of the deep flexor digitorum muscle. Both muscle bellies were connected by a 1.42mm thick tendon that passed beneath the median nerve and ran through the carpal tunnel. The second belly was enlarged and entered the distal part of the carpal tunnel. Interestingly, the donor revealed further rare variations such as a bilateral regression of the fifth superficial flexor tendons to an obviously non functional connective tissue strand, lack of both palmaris longus muscles, a discoid lateral meniscus in the left knee, and reduction of the plantaris muscle to a fascia-like structure on the right leg. Lumbrical muscle variations extending into the carpal tunnel, especially those associated with auxiliary tendons, have significant clinical relevance due to their association with carpal tunnel syndrome.

Variaciones del músculo palmar largo en la población de Caldas (Colombia) / Variations of the palmaris longus muscle in the population of Caldas (Colombia)

El músculo palmar largo es de los músculos más variables en su presentación en el cuerpo humano. El propósito del estudio fue determinar su grado de agenesia en una muestra de individuos del Departamento de Caldas (Colombia). Se evaluó la presencia del músculo palmar largo por visualización directa de su tendón, para lo cual se aplicó el test de Thompson, y cuando fue necesario se aplicó el Test de Schaeffer, en una muestra de 115 individuos de sexo femenino y masculino entre los 17 a 50 años de edad oriundos de Caldas. La agenesia global del palmar largo se encuentra en el 22,6 % de la población caldense, pero la agenesia bilateral sólo se presenta en el 8,69 % de los individuos, siendo mayor su presentación en las mujeres; mientras que la agenesia unilateral es más frecuente, por el orden del 13,91 %, guardando una proporción semejante entre hombres y mujeres. Aunque existe cierta concordancia con la mayoría de estudios realizados en otros países, nuestro estudio destaca dos hechos relevantes, que la agenesia global músculo del palmar largo tiene una de las frecuencias más elevadas de presentación, y que la agenesia unilateral, tanto derecha como izquierda, se encuentra entre los rangos más bajos. La agenesia global del músculo, bilateral y unilateral, es más común en las mujeres. Así mismo, la agenesia bilateral es más frecuente en las mujeres, con una presentación que duplica la de los hombres, mientras que la agenesia unilateral es proporcionalmente igual en ambos sexos.

The palmaris longus muscle is one of the most variable muscles in its presentation in the human body. The purpose of the study was to determine the degree of agenesis of this muscle in a sample of individuals in the Department of Caldas (Colombia). The presence of palmaris longus muscle by direct visualization of the tendon was evaluated by applying Thompson`s test and where necessary, Schaeffer`s test, in a sample of 115 individuals (female and male) between 17-50 years old, all natives of Caldas. The overall agenesis of palmaris longus muscle is in the 22.6 %, but bilateral agenesis occurs only in 8.69 % of individuals, being higher in women, while unilateral agenesis is more common in the order of 13.91 %, keeping a similar proportion of men and women. Although there is some agreement with most of the studies made in other countries, our study highlights two important events, the global agenesis of palmaris longus muscle has one of the highest frequencies of submission, and that the unilateral agenesis, both right and left is among the lower ranks. Bilateral and unilateral global muscle agenesis is more common in women. Likewise, bilateral agenesis is more frequent in women, with a presentation that doubles that of men, while unilateral agenesis is proportionally equal in both sexes.

Morphological variability of the palmaris longus muscle in human fetuses.

PURPOSE: The palmaris longus (PL) muscle is characterized by high-morphological variability. It is clinically important as it is routinely harvested for the reconstruction of other tendons. The study characterizes the morphology of the PL in human fetuses and creates a new classification based on its variations that would relate to the spectrum of morphological variability in adults. METHODS: Eighty spontaneously aborted human foetuses (44 male, 36 female, 160 upper limbs), aged 18-38 weeks of gestation, were examined. RESULTS: The palmaris longus muscle was present in 62.5% of fetuses. The absence was bilateral in 26.25%, and unilateral in 22.5%. Nine types of palmaris longus muscles were identified based on the morphology of its insertion (Types I-IX). All types originated on the medial epicondyle of the humerus. The most common type was Type I, which was characterized by insertion to the palmar aponeurosis (52%). The rarest types were Type VII and Type IX (1% each). Type VII was characterized by partial doubling of the muscle belly, which then turned into two separate tendons that inserted together into the palmar aponeurosis. Type IX was characterized by fusion with the flexor carpi ulnaris muscle. CONCLUSION: Our findings concerning morphological variability of the PL in fetuses present a new perspective on the understanding nature of the morphological variation of the PL muscle in adults. LIST OF EVIDENCE: Basic Science Study.

The sonographic morphology of musculus palmaris longus in humans.

BACKGROUND: The aim of this work was to describe morphology and morphometry of musculus palmaris longus and compare the outcome of Shaeffer's test with ultrasound imaging. MATERIALS AND METHODS: Forty forearms of 20 healthy volunteers (11 females, 9 males) were tested by Shaeffer's test and ultrasound imaging. Anthropological measurements of the forearm and ultrasound guided measurements of musculus palmaris longus were taken. The outcome was tested for statistical significance by Fisher's test. RESULTS: The examination revealed agenesis of palmaris longus in 6 cases, as well as 6 muscles showing quality variations. The Shaeffer's test gave 4 false-negative results. 28 muscles were described as spindle-shaped and 8 as pennated or bipennated. However, all the spindle-shaped muscles demonstrated a tendon going inside of the muscle's belly ranging from 2 cm to 11.5 cm. The relation between the circumference of the forearm right below the elbow (mean: 15.38 cm, SD: 1.83 cm) and the approximated volume of the palmaris longus muscle's belly (mean: 4.72 cm3, SD: 1.57 cm3) proved to be statistically significant (Fisher's test p-value < 0.05). CONCLUSIONS: Uncommon morphological variations have been shown. Spindle-shaped muscles have proved to have their tendons continued inside them. Palmaris longus muscle's belly has proved to take significant amount of volume within the proximal forearm. Shaeffer's test has shown to have 10% false-negative ratio.

Hypertrophic reversed palmaris longus muscle: a cadaveric finding.

Variations of the forearm musculature are vastly described in the literature. The palmaris longus muscle is one of the most variable structures of the human body. It usually arises from the medial epicondyle of the humerus and inserts itself into the palmar aponeurosis. Anatomy textbooks and recent papers state that this muscle may act as a weak wrist flexor. The present work aims to report an anatomical variation where the palmaris longus muscle was abnormally hypertrophied and was completely fleshy throughout the whole forearm. Anatomical variations of the palmaris longus may induce symptoms of neurovascular bundle compression, especially of the median nerve. The palmaris longus muscle may be used in tendon graft or muscle graft, due to its lack of apparent function. Furthermore, it is one of the anatomical landmarks for local anaesthesia procedures. (Folia Morphol 2018; 77, 2: 403-405).

Anatomical variations of the palmaris longus muscle including its relation to the median nerve - a proposal for a new classification.

BACKGROUND: The palmaris longus (PL) muscle is characterised by high morphological diversity, and its tendon crosses the median nerve (MN) at different levels. Due to the fact that the palmaris longus tendon is routinely harvested for reconstruction of other tendons, knowledge of its morphological variations is clinically important. Therefore, the purpose of the study was to suggest a new morphological classification of the PL muscle and characterise the relationship of its tendon to the median nerve. METHODS: Standard dissection was performed on 80 randomised and isolated upper limbs (40 left and 40 right) fixed in a 10% formalin solution. Measurements of muscle belly and tendon were obtained. The course and location of tendon insertion, as well as its relationship to the median nerve, were noted. RESULTS: The palmaris longus muscle was present in 92.5% of specimens. Three types of palmaris longus muscle were identified based on the morphology of its insertion (types I-III) and these were further subdivided into three subgroups (A-C) according to the ratio of the length of the muscle belly and its tendon. The most frequent was type I (78.8%), where the tendon attached to the palmar aponeurosis, and subtype B, where the tendon-to-belly ratio was 1-1.5 (41.1%). The mean distance from the interstyloid line to the crossing between the median nerve and the palmaris longus tendon was 31.6 mm. In addition, two types of palmaris longus were described. CONCLUSION: The presented classification of palmaris longus muscle types allows a better characterization of its diversity and may be useful in planning tendon grafting.

Palmaris Longus Muscle Variations: Clinical Significance and Proposal of New Classifications.

BACKGROUND: The palmaris longus muscle is one of the most variable muscles in the human body and there have been numerous variations reported. The different palmaris longus variations are interesting not only from an anatomical point of view, but they could also have definite clinical significance. AIM: The aim of this study was to examine the different types of variations of palmaris longus muscle in the Bulgarian population. MATERIALS AND METHODS: Over a period of 15 years, 56 formol-carbol fixed human cadavers were studied to investigate the different variations of palmaris longus muscle (PLM). RESULTS: Various anatomical variations of PLM have been reported: absence (2.68%); reversed palmaris longus coexisting with an additional abductor digiti minimi muscle (0.89%); digastric (0.89%); palmaris longus with intermediate muscle belly (1.79%) and duplication (1.79%). CONCLUSIONS: To reveal the wide variety of the types of palmaris longus muscle and their importance for clinical practice, we make a brief literature review concerning the different types of variations, their role in the median and ulnar neuropathy in the wrist or as structures simulating a soft tissue tumour and the application of palmaris longus tendon in plastic and reconstructive surgery as grafting material. We also present new systematic anatomical and clinical classifications of palmaris longus variations by dividing them into two simple groups.

Congenital absence of the palmaris longus muscle: A meta-analysis comparing cadaveric and functional studies.

The aim of our paper was to provide comprehensive data on the prevalence of absence of palmaris longus muscle (PLM) and its anatomical characteristics and conduct two separate meta-analyses comparing cadaveric and functional studies while identifying variation among different ethnic groups. An extensive search was conducted through the major electronic databases to identify eligible articles. Data extracted included prevalence of absence of PLM among subjects, ethnicity, laterality, side, and gender. Our main findings revealed that the absence of PLM is more frequently reported in functional studies. Moreover, functional tests likely overestimated the absence of PLM and recommend future studies to assess the validity of functional tests and use an imaging assessment prior to excluding the use of a palmaris longus tendon graft in patients in whom a function test identified the absence of PLM.

Evolutionary Transformation of the Palmaris Longus Muscle in Flying Squirrels (Pteromyini: Sciuridae): An Anatomical Consideration of the Origin of the Uniquely Specialized Styliform Cartilage.

A long-standing issue in squirrel evolution and development is the origin of the styliform cartilage of flying squirrels, which extends laterally from the carpus to support the gliding membrane (patagium). Because the styliform cartilage is one of the uniquely specialized structures permitting gliding locomotion, the knowledge of its origin and surrounding transformation is key for understanding their aerodynamic evolution. The developmental study that would definitely answer this question would be difficult due to the rarity of embryological material. Instead, anatomical examinations have suggested two major hypotheses on the homology of the styliform cartilage: the pisiform bone of other mammals, or an additional carpal structure, such as the ulnar sesamoid of some of the other mammals or the hypothenar cartilage of the non-gliding squirrels. To test these hypotheses, a detailed examination of the anatomy of the carpus of gliding and non-gliding squirrels, and the colugo were undertaken. Based on physical and virtual dissections of the carpus, this study showed that both the pisiform bone and styliform cartilage were present in flying squirrels. This finding is further supported by demonstration that a "true Palmaris longus," with innervation typical for this muscle, inserts on the styliform cartilage. Taken together, our osteological, muscular, and neurological results suggest that the styliform cartilage was transformed in flying squirrels from an initially superficial and ulnar-derived anlagen into its current form. Anat Rec, 300:340-352, 2017. © 2016 Wiley Periodicals, Inc.

Morphology and morphometry of the tendons of the palmaris longus and radial carpal extensor muscles in humans / Morfología y morfometría de los tendones de los músculos palmar largo y extensores radiales del carpo en el hombre

The tendons of the palmaris longus (PL) and radial carpal extensor (RCE) muscles have extensive applications in surgery, yet despite their constant use, information about their morphological and morphometric characteristics remains limited. The aim of this study was to describe the morphological and morphometric characteristics of the PL and RCE muscle tendons and compare them to each other in 30 upper limbs of adult individuals with no apparent deformations from anatomy units at four universities in Chile. The anterior side and lateral margin of the forearm and the back of the hand as far as the tendon plane were dissected. The average length, width at origin level and at the level of the radiocarpal joint line of the PL muscle tendon were 125.48 mm ± 8.93, 4.76 mm ± 1.35 and 3.76 mm ± 0.91, respectively. The average length, width at the levels of origin and insertion of the extensor carpi radialis longus muscle tendon were 180.46 mm ± 15.03, 14.69 mm ± 3.72 and 7.76 mm ± 1.44 respectively, whereas for the extensor carpi radialis brevis muscle they were 115.23 mm ± 11.81, 9.53 mm ± 2.58 and 7.33 mm ±1.17, respectively. The most common origin of the tendons of the PL and extensor carpi radialis longus muscles was at the level of the middle third of the forearm, whereas the most common origin of the extensor carpi radialis brevis muscle tendon was at distal third level. The shape of the tendons of the PL and RCE muscles was broad and flat along their entire length. Simulating the longitudinal division of the tendons of the RCE muscles in two halves, the radial half of the tendons of both muscles has morphological and morphometric characteristics similar to the PL muscle tendon, such that it could be used as a graft in the case of agenesis of the PL muscle, or for tendon transfer where elongation of a tendon in the region is required.

Los tendones de los músculos palmar largo (PL) y extensores radiales del carpo (ERC) tienen extensas aplicaciones en cirugía, pero a pesar de su constante uso, es escasa la información respecto a sus características morfológicas y morfométricas. El objetivo de este estudio fue describir las características morfológicas y morfométricas de los tendones de los músculos PL y ERC y compararlas entre sí, en 30 miembros superiores de individuos adultos, sin deformaciones aparentes, pertenecientes a unidades de anatomía de cuatro universidades de Chile. Se disecó la cara anterior y el margen lateral del antebrazo, y el dorso de la mano, hasta llegar al plano de los tendones. Los promedios de longitud, anchos a nivel del origen y a nivel de la línea articular radiocarpiana del tendón del músculo PL fueron de 125,48 mm ± 8,93, 4,76 mm ± 1,35 y 3,76 mm ± 0,91, respectivamente. Los promedios de longitud, anchos a nivel de origen y a nivel de la inserción del tendón del músculo extensor radial largo del carpo fueron de 180,46 mm ± 15,03, 14,69 mm ± 3,72 y 7,76 mm ± 1,44, mientras que para el tendón del músculo extensor radial corto del carpo fueron de 115,23 mm ± 11,81, 9,53 mm ± 2,58 y 7,33 mm ±1,17, respectivamente. El origen más común de los tendones de los músculos PL y extensor radial largo del carpo fue a nivel del tercio medio del antebrazo, mientras que el origen más común del tendón del músculo extensor radial corto del carpo fue a nivel del tercio distal del antebrazo. La forma de los tendones de los músculos PL y ERC era ancha y plana durante toda su extensión. Al simular la división longitudinal de los tendones de los músculos ERC en dos mitades, la mitad radial de los tendones de ambos músculos presenta características morfológicas y morfométricas similares al tendón del músculo PL, por tanto, eventualmente podrían ser utilizadas para injerto en caso de agenesia del músculo PL, o para transferencia tendinosa, en caso de que se requiera un alargamiento de algún tendón de la región.

A combined variation of Palmaris longus and Flexor digitorum superficialis: Case report and review of literature.

The muscles of the anterior compartment of the forearm often exhibit anatomic variations. During dissection of the upper right limb of a preserved cadaver, morphological variations in the Palmaris longus and Flexor digitorum superficialis muscles were found. The Palmaris longus muscular fibers converged to a tendon that passed beneath the Flexor retinaculum, and inserted at the base of the middle phalanx of the fourth digit, replacing the tendon of Flexor digitorum superficialis. The Flexor digitorum superficialis was divided into two muscular heads: a digastric medial head giving tendons to the second and fifth digits, and a lateral head giving one tendon to the third digit. All these tendons were inserted in the respective digits by two bundles between which were located the tendon of the Flexor digitorum profundus muscle. Variations of flexor muscles must be documented because of their clinical significance and their potential use of these muscles in orthopaedic and reconstructive surgery.

The first description of the absence of the palmaris longus muscle.

BACKGROUND: While Realdo Colombo from Cremona, Italy has, to date, been acknowledged to be the first to describe the possible absence of the palmaris longus muscle in men in 1559, the authors found this absence to be recorded in the first edition of "De Humani Corporis Fabrica Libri Septum" by Andreas Vesalius, published in 1543. METHOD: To commemorate Vesalius' 500th birthday, this earlier record is quoted and discussed. RESULTS AND CONCLUSION: It remains unknown whether the observation on the absence of the palmaris longus was first done by Vesalius or was based on joined work by Vesalius and Colombo.

Change of the agenesis rate of palmaris longus muscle in an isolated village in Ukraine.

BACKGROUND: The palmaris longus muscle (PLM) is a slender, fusiform muscle which lies on the flexor surface of the forearm. Its agenesis is considered the most frequent anatomic variation in the human body. Agenesis of PLM shows strong racial and ethnic variability. The aim of this study was to examine the prevalence of agenesis of PLM in Dercen, an isolated Hungarian village in Ukraine. MATERIALS AND METHODS: Five hundred forty-eight persons were examined by Thompson's, Shaffer's, Pushpakumar's, Mishra's 1, and Mishra's 2 tests to confirm or refute the presence of a PLM. All the examined subjects were of Hungarian ethnic origin. RESULTS: The overall prevalence of absence of the palmaris longus was 52.92%. During the examination, unusual results appeared regarding the agenesis of PLM in the elder population of village. Further tests among elder population shoved that in people born before 1945 the agenesis rate of PLM was higher than 70%, and in villagers born after 1945 the agenesis rate drops by 23%. CONCLUSIONS: In the light of historical events of the country, we can say that the unexpected change of the PLM agenesis rate in 1945 was caused by invasion of soviet army and deportation of local men from their homeland.

Prevalence of agenesis of the palmaris longus muscle in Brazil and its clinics correlation

Introduction: The palmaris longus muscle 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 determine the prevalence of unilateral and bilateral agenesis of palmaris longus muscle for the subjects in the city of Jataí, Goiás. Material and methods: 740 subjects, 279 men and 461 women, in the age of 10-70 years old, were observed through clinical inspection in both forearms to absence of the tendon of palmaris. The data were described in percentage values and the absence of the muscle was analyzed statistically (Chi square test; P < 0.05). Results: The bilateral presence was identified in 73.5%, the absence on the left side in 7.8%, on the right in 6.5% and bilateral absence was observed in 12.2% of subjects. Among women and men the percentage values was 9.3%, 7.3%, 13.1% and 5.4%, 5%, 10.7%, respectively to agenesis in left side, in right side and bilateral agenesis. The unilateral/bilateral agenesis was more frequent in women (29.7%) than in men (21.1%; P < 0.05). Bilateral absence was 12.4% in right handed subjects and 9.1% in left handed subjects (P > 0.05). Left and right handed subjects showed absence of muscle similar in both forearms (P > 0.05). Conclusion: most subjects studied showed bilateral presence of palmaris longus muscle, the agenesis was significantly more common in women and with similar percentage in right and left handed subjects.

Múltiples Variaciones Musculares y Neurovasculares en los Miembros Superiores: Presentación de Caso / Multiple Muscle and Neurovascular Variations in the Upper Limbs: Case Report

Se presenta un raro caso de múltiples variaciones en los miembros superiores de un espécimen cadavérico de 45 años de género masculino, del laboratorio de morfología de la Universidad Industrial de Santander (Bucaramanga-Colombia). Se observó variaciones musculares (presencia bilateral de cabezas adicionales del bíceps braquial y del musculo flexor largo del pulgar, agenesia del palmar largo derecho), nerviosas (anastomosis entre mediano y nervio musculocutáneo, y entre ulnar y mediano al nivel palmar superficial). Adicionalmente, presentó el origen de la arteria radial izquierda desde el segmento superior de la braquial. Estas diversas expresiones morfológicas determinan relevantes implicaciones clínicas y deben tenerse en cuenta en los diferentes abordajes quirúrgicos de los miembros superiores.

It is presented a rare case of multiple variations in the upper limbs of a 45 years old male cadaver specimen, ownership of the morphology laboratory of the Universidad Industrial de Santander (Bucaramanga, Colombia). Muscle variations were observed (presence of both additional heads of the biceps brachii and the flexor pollicis longus, agenesis of right palmaris longus), nervous variations (anastomosis between median and musculocutaneous nerve and between ulnar and median at superficial palmar level). Additionally it presented the radial artery origin from upper left segment of the brachial artery. These various morphological expressions determine relevant clinical implications and should be taken into account in the various surgical approaches to the upper limbs.

Agenesis of Palmaris Longus Muscle in Selected Population of School Children in Nigeria / Agenesia del Músculo Palmar Largo en una Población Seleccionada de Niños en Edad Escolar de Nigeria

The aim of this study is to evaluate the prevalence of agenesis of palmaris longus muscle tendon among school children in Ogun state, Southwestern Nigeria and also, to verify the symmetry of the agenesis of the muscle in relation to sex. The presence of the palmaris longus muscle tendon was determined in 564 individuals, 285 male and 279 female, with age varying from 2 to 20 years old. Four different tests were used; Schaeffer's test, Thompson's test, Mishra's test 1 and Pushpakumar's "two-finger sign" method. The data obtained were further analyzed statistically and the agenesis of palmaris muscle was found to be 26.7% (unilateral 13.0%; bilateral 13.7%). Prevalence was higher in female (32.3%) than male (21.4%) (P>0.05). Besides, we observed higher agenesis in the left side in female individuals. High prevalence of agenesis of palmaris muscle observed in the study population is similar to other previous reports in Southwestern Nigeria.

El objetivo de este estudio fue evaluar la prevalencia de agenesia del tendón del músculo palmar largo entre niños en periodo escolar del Estado de Ogun, sudoeste de Nigeria, y verificar además, la simetría de la agenesia del músculo en relación al sexo. La presencia del tendón del músculo palmar se determinó en 564 individuos, 285 hombres y 279 mujeres, con edades que variaban entre 2 y 20 años de edad. Se utilizaron cuatro ensayos diferentes; prueba de Schaeffer, prueba de Thompson, prueba de Mishra 1 y método de Pushpakumar "signo de dos dedos". Los datos obtenidos fueron analizados estadísticamente, donde se encontró que la agenesia del músculo palmar fue de 26,7% (13% unilateral; 13,7% bilateral). La mayor prevalencia fue en el sexo femenino (32,3%), siendo hombres (21,4%) (p> 0,05). Además, se observó mayor agenesia derespecto al lado en mujeres. La alta prevalencia de agenesia del músculo palmar largo observada fue similar a la encontrada en informes en el Suroeste de Nigeria.

Study of Frequency of the Palmaris Longus Musclem in Chilean Subjects / Estudio de la Frecuencia del Músculo Palmar Largo en Individuos Chilenos

The 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 percent of the individuals had the PLM muscle tendon in at least one of the forearms and 80 percent in both forearms. The unilateral agenesis was found in 11 percent of the cases (5 percent on the right side and 6 percent on the left side) and bilateral agenesis was found in 9 percent 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 percent) than in women (78.07 percent) (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).

El músculo palmar largo (MPL), ubicado en la región anterior del antebrazo, es considerado como uno de los músculos más variables del cuerpo humano, siendo su agenesia la variación anatómica más frecuentemente señalada por los investigadores. El objetivo de este estudio fue investigar la frecuencia del tendón del músculo palmar largo en individuos chilenos y verificar la simetría de la agenesia según el sexo. Para ello, analizamos la presencia del tendón del MPL en 200 individuos chilenos, 114 mujeres y 86 hombres. Fueron utilizadas 3 pruebas: Prueba Schaeffer, Primera Prueba de Mishra y Prueba Thompson. Los datos obtenidos fueron registrados y tabulados. Se observó que el 91 por ciento de los sujetos presentaron el tendón del MPL al menos en uno de los antebrazos, mientras que un 80 por ciento lo presentaron en ambos antebrazos. Se observó aún que la agenesia unilateral estuvo presente en un 11 por ciento de los casos (5 por ciento en el lado derecho y 6 por ciento en el lado izquierdo), ya la agenesia bilateral estuvo presente en 9 por ciento. Al analizar la presencia (unilateral y bilateral) del tendón del PLM considerando el sexo, se observó en el 82,56 por ciento de los hombres y en el 78,07 por ciento 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).

Incidence of palmaris longus muscle absence in nigerian population / Incidencia de la ausencia del músculo palmar largo en la población de Nigeria

A lot has been reported about variation of palmaris longus muscle in journals and conventional textbooks. The incidence of palmaris longus muscle absence among people of the six geo-political zones of Nigeria was evaluated using 600 subjects. 31.25 percent (187 subjects) lack palmaris longus muscleon either of the forearms. 12.5 percent (75 subjects) shows unilateral absence and 18.75 percent (112 subjects) shows bilateral absence. 25 percent (150) of subjects lacks palmaris longus muscleon their right forearms while 25 percent also lacks it on their left forearms. 6 percent (37) shows double tendons of palmaris longus muscleon both forearms. Highest incidence of absence was recorded among people of South-West zone.

Mucho se ha informado acerca de la variación del músculo palmar largo en revistas y libros de texto convencionales. La incidencia de ausencia del músculo palmar largo entre las personas de las seis zonas geo-políticas de Nigeria se evaluó usando 600 sujetos. 31,25 por ciento (187 sujetos) no tenían músculo palmar largo en cualquiera de los antebrazos, 12,5 por ciento (75 sujetos) mostró ausencia unilateral y 18,75 por ciento (112 sujetos) mostró ausencia bilateral. 25 por ciento (150) de los sujetos carece de músculo palmar largo en su antebrazo derecho, mientras que el 25 por ciento carece de él también en su antebrazo izquierdo. 6 por ciento (37) muestra dobles tendones de músculo palmar largo en ambos antebrazos. Mayor incidencia de ausencia se registró entre las personas de la zona Sur-Oeste.