Influence of probe position in the measurement of muscle thickness and its association with lean mass: an ultrasound study / Influencia de la posición de la sonda en la medición del grosor muscular y su asociación con la masa magra: un estudio ecográfico

SUMMARY: Skeletal muscles play a fundamental role in people's lives and their evaluation provides significant information on health. Different tools have been used to evaluate muscle mass, and the evaluation of muscle thickness (MT) using ultrasound has been included as an alternative, which can be performed with the probe in different positions; however, these could present differences. The objectives of this study were to determine whether there are differences in the measurement of MT in the vastus lateralis (VL) muscle using the probe in the longitudinal or transverse position, and to determine its association with the lean mass of the lower limbs. The results indicated no significant differences between MT measurements with the probe in the longitudinal and transverse positions (p =0.084). However, when associating these measurements with lower limb lean mass, it was found that transverse measurements had a strong association (r =0.547; p < 0.001), while longitudinal measurements had a moderate association (r =0.351; p =0.007). This suggests that measurements with the probe positioned transversely to measure the MT would be the best option. Therefore, it could be useful as an indicator of lower limb lean mass in the absence of tools, such as bioelectrical bioimpedance or magnetic nuclear resonance.

El músculo esquelético cumple un rol fundamental en la vida de las personas, y su evaluación entrega mucha información de la salud. Se han utilizado diferentes herramientas para evaluar la masa muscular, y el último tiempo se ha incluido la evaluación del grosor muscular (MT) a través de la ecografía como una alternativa para estimarla, las cuales se pueden realizar con la sonda en distintas posiciones, sin embargo, estas podrían presentar diferencias. Los objetivos del estudio fueron determinar si existen diferencias en la medición de MT en el músculo vasto lateral (VL) utilizando la sonda en posición longitudinal o transversal y determinar su asociación con la masa magra de los miembros inferiores. Los resultados indican que no existen diferencias significativas entre las mediciones de MT con la sonda en posición longitudinal y transversal (valor p: 0.084). Sin embargo, al asociar estas mediciones con la masa magra de los miembros inferiores, se encontró que las mediciones transversales poseen una asociación fuerte (r: 0.547; valor p < 0.001), mientras que las mediciones longitudinales presentan una asociación moderada (r: 0.351; valor p: 0.007). Esto sugiere que las mediciones con la sonda posicionada transversal para medir MT serían la mejor opción. Por lo tanto, podría ser de utilidad como un indicador de masa magra de los miembros inferiores en caso de no contar con herramientas como la bioimpedancia bioeléctrica o resonancia nuclear magnética.

Surgical repair of the supraspinatus: pre- and postoperative architectural changes in the muscle

INTRODUCTION@#Shortening of the tendon and muscle is recognised as a strong predictor of surgical failure of supraspinatus tendon tears. Changes in muscle architecture following repair have not been thoroughly investigated. Hence, we aimed to compare the pre- and postoperative architecture of the supraspinatus.@*METHODS@#We recruited eight participants with full-thickness supraspinatus tears. Images of the supraspinatus were captured preoperatively (pre-op) and postoperatively at one month (post-op1), three months (post-op2) and six months (post-op3) in relaxed and contracted states (0º and 60º glenohumeral abduction). Fibre bundle length (FBL), pennation angle (PA) and muscle thickness were quantified. Self-reported function, and maximal isometric abduction and external rotation strengths were assessed.@*RESULTS@#The mean FBL increased from pre-op to post-op1 (p = 0.001) in the relaxed state and from pre-op to post-op2 (p = 0.002) in the contracted state. Decrease in FBL was observed from post-op2 to post-op3 in the relaxed state. The mean PA decreased from pre-op to post-op1 (p < 0.001) in the relaxed state, but increased from post-op2 to post-op3 in both relaxed (p = 0.006) and contracted (p = 0.004) states. At post-op3, external rotation (p = 0.009) and abduction (p = 0.005) strengths were greater than at post-op2. Overall function increased by 47.67% from pre-op to post-op3.@*CONCLUSION@#Lengthening of the supraspinatus occurs with surgery, altering the length-tension relationship of the muscle, which can compromise muscle function and lead to inferior surgical outcomes. These findings may guide clinicians to optimise loads, velocities and shoulder ranges for effective postoperative rehabilitation.

Relationship between upper and lower limbs muscle explosive strength with the vastus lateralis and biceps brachii architecture / Correlação entre a força muscular explosiva dos membros superiores e inferiores com a arquitetura do vasto lateral e do bíceps braquial / Correlación entre la fuerza muscular explosiva de las extremidades superiores e inferiores con la arquitectura del vasto lateral y el bíceps braquial

ABSTRACT We aimed to assess upper and lower limbs explosive strength, and its correlation with biceps brachii (BB) and vastus lateralis (VL) architecture. Absolute and maximum torque normalized rate of torque development (RTD) were measured from isometric elbow flexion (EF) and knee extension (KE). BB and VL architectures were assessed by ultrasound. Absolute RTD of KE was higher (129-272%), although normalized RTD was higher in EF (80-21%). The absolute RTD was correlated to muscle thickness only in the BB (r=.39-46). No relationship was found between muscle architecture and normalized RTD. In conclusion, the higher RTD from KE seems to be due to their greater strength. Only the muscle architecture could not explain the differences found in the RTD.

RESUMO Nosso objetivo foi avaliar a força explosiva de membros superiores e inferiores e a sua correlação com a arquitetura do bíceps braquial (BB) e vasto lateral (VL). A taxa de desenvolvimento de torque (TDT) absoluta e normalizada pela força máxima foi medida na flexão de cotovelo (FC) e extensão de joelho (EJ). A arquitetura do BB e do VL foi avaliada por ultrassonografia. A TDT absoluta de EJ foi maior (129-272%), mas a TDT normalizada foi maior na FC (80-21%). A TDT absoluta foi correlacionada com a espessura do BB (r=.39-46). A TDT normalizada não foi correlacionada à arquitetura muscular. Concluindo, a TDT superior da EJ parece causada pela maior força máxima. Apenas a arquitetura muscular não parece explicar a diferença na TDT.

RESUMEN Nuestro objetivo era evaluar la fuerza explosiva de los miembros superiores y inferiores y su correlación con la arquitectura del bíceps braquial (BB) y vasto lateral (VL). Se medio la tasa de desarrollo de torque (TDT) absoluta y normalizada por la fuerza máxima in la flexión de codo (FC) e extensión de rodilla (ER). La arquitectura del BB y VL fue evaluada por ultrasonido. La TDT absoluta de ER fue mayor (129-272%), pero la TDT normalizada fue mayor en la FC (80-21%). La TDT absoluta se correlacionó con el grosor del BB (r=.39-46). La TDT normalizada no se correlacionó con la arquitectura. En conclusión, la TDT superior del ER parece estar causado por la mayor fuerza máxima. La arquitectura muscular sola no parece explicar la diferencia en la TDT.

Variação aguda não uniforme da espessura muscular ao longo do peitoral maior em resposta ao supino reto em homens treinados / Non-uniform acute variation among pectoralis major's muscle thickness after bench press in trained men / Variación aguda no uniforme del espesor muscular al largo del pectoral mayor en respuesta al press de banca en hombres entrenados

O objetivo do estudo foi comparar a variação da espessura muscular (EM) ao longo do peitoral maior (PM) após três séries de 8 a 12 repetições máximas de supino reto. A amostra foi composta por 12 homens treinados. O comportamento da EM foi avaliado pré e imediatamente após a realização do exercício através de ultrassonografias, em três sítios do feixe esternal do PM: medial (próximo ao esterno), central e lateral (próximo ao úmero). Como resultado, o sítio medial apresentou variação relativa da EM de 14,78%, o central de 11,83% e o lateral de 10,04%, com diferença significativa apenas entre o sítio medial quando comparado ao lateral (p=0,036). Tal efeito pode estar relacionado a maior ativação do trecho medial do PM durante o supino reto ou pela específica morfologia do PM.

The aim of this study was to compare the variation of muscle thickness (MT) over the pectoralis major muscle (PM) after 3 sets of 8 to 12 repetitions of bench press. The sample was consisted of 12 trained men. Ultrasound images were acquired, to analyze the MT behavior, at three sites of the PM's sternal head: medial, central and lateral. The medial site had a MT relative variation of 14.78%, the central one of 11.83% and the lateral one of 10.04%, with a statistical difference observed only between the medial site when compared to the lateral site (p = 0.036); The possible cause of these effects might be related to a possible greater activation of the medial site during the bench press or due to PM's morphology. We conclude that the PM shows heterogeneous MT acute variation.

El objetivo del estudio fue comparar la variación de la espesura muscular (EM) a lo largo del pectoral mayor (PM) después de tres series de 8 a 12 repeticiones de press de banca. El comportamiento de la EM fue evaluado pre e inmediatamente después de la realización del ejercicio con ultrasonografías, en tres sitios de la cabeza esternal del PM: medial (cerca del esternón), central y lateral (cerca del húmero). Como resultado, el sitio medial presentó 14,78% de variación relativa de la EM, el central 11,83% y el lateral 10,04%, con diferencia significativa apenas entre el sitio medial cuando comparado al lateral (p = 0,036) . Este efecto puede estar relacionado con la mayor activación del sitio medial del PM durante el press de banca o por la morfología del PM.

Architectural Changes in the Medial Gastrocnemius on Sonography after Nerve Ablation in Healthy Adults

Architectural changes in healthy muscle after denervation have not yet been reported. This study aimed to investigate architectural changes in the medial head of the gastrocnemius muscle (GCM) after aesthetic tibial nerve ablation in healthy adults using ultrasonography (US). The effects of tibial nerve ablation were verified by visual observation and surface electromyography analysis. US images of medial GCMs were taken by one trained physician using B-mode and real-time US with a linear-array probe before nerve ablation, at 1 week after nerve ablation and at 3 months after nerve ablation in an anatomic standing position with the feet about shoulder-width apart in 19 healthy adults (17 females and 2 males). Muscle thickness was significantly reduced on the left side at 1 week and 3 months after the procedure and on the right side at 3 months after the procedure (p<0.050). Although fascicle length was not significantly changed, pennation angle was significantly reduced on both sides at 3 months after the procedure (p<0.050). Muscle thickness and pennation angle of the muscle fascicle were significantly reduced, although fascicle length was not significantly changed, after tibial nerve ablation in the medial GCM of healthy adults.

Reliability of biceps femoris and semitendinosus muscle architecture measurements obtained with ultrasonography

Introduction Currently, little attention is given to the muscle architecture reliability studies of the hamstring using a robust statistical. Our purpose was to determine the reliability of ultrasound measurements of muscle thickness, fascicle length and pennation angle of the biceps femoris and semitendinosus muscles, including heteroskedasticity and internal consistency analyses. Methods Two images of biceps femoris and semitendinosus at 50% of the thigh length were acquired from 21 volunteers, in two visits. The parameters were measured three times in each image, and for each muscle. The reliability was analyzed by the intraclass correlation coefficient (ICC) and Cronbach’s alpha (αCronbach). The relative standard error of the measurements (%SEM) were calculated and Bland-Altman plots were generated. Results All parameters presented excellent ICC for the three repeated measurements (ICC from 0.93 ‒ 0.99) and moderate to excellent reliability intraday (ICC from 0.70 ‒ 0.95) for both muscles. The present study indicates that ultrasound is a reliable tool to estimate the biceps femoris fascicle length (ICC = 0.97, αCronbach = 0.98, %SEM = 7.86) and semitendinosus (ICC = 0.90, αCronbach = 0.95, %SEM = 7.55), as well as the biceps femoris muscle thickness (ICC = 0.89, αCronbach = 0.94, %SEM = 10.23) and semitendinosus muscle thickness (ICC = 0.87, αCronbach = 0.93, %SEM = 1.35). At last, biceps femoris pennation angle (ICC = 0.93, αCronbach = 0.96 and %SEM = 4.36) and semitendinosus (ICC = 0.96, αCronbach = 0.98 and %SEM = 4.25) also had good repeatability. Conclusion Ultrasonography show good repeatability in estimating of muscle architecture parameters.

Vastus lateralis muscle architecture to estimate knee extension moment of older individuals / Arquitetura do músculo vasto lateral para estimar o momento de extensão do joelho de indivíduos idosos / Arquitectura de los vasto lateral para estimar el momento de la extensión de la rodilla de las personas ancianas

The aim of this study was to compare the knee extension moment of older individuals with the muscle moment estimated through a biomechanical model. This was accomplished by using (1) the specific muscle architecture data of individuals, and (2) the generic muscle architecture available in the literature. The muscle force estimate was determined using a model with the muscle architecture from cadavers and the individual vastus lateralis muscle architecture of sixteen older volunteers. For the muscle moment comparison, all of the volunteers performed maximal voluntary isometric contractions (MVIC) in five different knee extension position angles. The architectural data was acquired using both resonance and ultrasound imaging. Both estimated muscle moments (generic and individual) were higher than the experimental. The architecture of the other vastii may be necessary to make the model more accurate for the older population. Although other factors inherent to ageing, such as co-contractions, fiber type percentage, and passive forces are not considered in the model, they could be responsible for the differences between moments in older people.

O objetivo deste estudo foi comparar o momento de extensão do joelho de idosos com momento muscular estimado por modelo biomecânico, utilizando (i) arquitetura muscular específica dos indivíduos e (II) arquitetura muscular genérica disponível na literatura. Para a estimativa da força muscular foi utilizado um modelo com a arquitetura muscular de cadáveres, e também com a arquitetura do vasto lateral de dezesseis voluntários idosos. Para a comparação todos voluntários realizaram contrações isométricas voluntárias máximas em cinco ângulos. Os dados de arquitetura foram adquiridos por meio de ultrassonografia e por ressonância magnética. Ambos os momentos estimados (genéricos e individuais) foram maiores do que experimental. A arquitetura dos outros músculos do quadríceps pode ser necessária para modelo ser mais preciso para a população idosa. Outros fatores inerentes ao envelhecimento não foram considerados no modelo, como cocontrações, tipagem de fibras e forças passivas, e devem ser responsáveis pelas diferenças entre os momentos.

El objetivo de este estudio fue comparar el torque extensión de la rodilla de ancianos con torque muscular estimado por modelo biomecánico, usando (i) la arquitectura muscular específica de los individuos y (II) (II) la arquitectura muscular genérica disponible en la literatura. Para la estimación de la fuerza muscular se utilizó un modelo con arquitectura muscular de cadáveres, y también con la arquitectura del vasto lateral de dieciséis voluntarios ancianos. Para la comparación todos los voluntarios realizaron contracciones isométricas voluntarias máximas en cinco ángulos. La arquitectura fue adquirida por ecografía y por resonancia magnética. Ambos las torques estimadas (genéricas y individuales) fueron mayores que el experimental. La arquitectura de los otros músculos de los cuádriceps puede ser necesaria para hacer el modelo más preciso para la población anciana. Otros factores inherentes envejecimiento no se consideran en el modelo, como co-contracciones, el tipo de fibra y fuerzas pasivas, y deben ser responsables de las diferencias entre las torques.

Efeito agudo de saltos intermitentes na arquitetura muscular do Vasto Lateral em atletas de voleibol / Acute effect of intermittent jumps on the Vastus Lateralis muscle architecture in volleyball players

O aumento do ângulo de penação de fibras musculares durante contração causa uma redução da geração de força do músculo. O objetivo deste estudo foi verificar a relação entre o ângulo de penação do músculo Vasto lateral (VL) com o rendimento em um teste de saltos verticais intermitentes. Foi testado um grupo de 18 atletas do sexo masculino da Confederação Brasileira de voleibol do Exército Brasileiro. Duas imagens longitudinais do VL, a 50% do comprimento da coxa, foram adquiridas com um Ultrassom modo-B. Posteriormente, os indivíduos realizaram um teste único do tipo Counter Movement Jump para avaliar a altura máxima do salto vertical. A tarefa de saltos verticais intermitentes compreendeu quatro séries de 15 segundos de saltos máximos. Imediatamente após a tarefa, duas imagens do ângulo de penação foram novamente adquiridas na mesma região. Duas medidas do ângulo de penação foram feitas em cada imagem, totalizando oito medições por indivíduo. Os resultados mostraram que houve redução significativa da altura dos saltos no decorrer da tarefa (35,77 ± 4,67 cm; 31,94 ± 4,51 cm; 27,04 ± 3,93 cm e 22,60 ± 3,66 cm para os intervalos de 0-15 s, 15-30 s, 30-45 s e 45-60 s, respectivamente). O ângulo de penação do VL não apresentou diferença significativa antes e após a realização da tarefa (12,72 ± 2,26º e 13,71 ± 3,40º, respectivamente). A correlação de Pearson entre as medidas do ângulo de penação no pré e pós teste intermitente e entre as alturas em todos os intervalos foram fracas (0,034

Increased pennation angle of the muscle fibers during contraction causes a reduced muscle force generation. The aim of this study was to investigate the relationship between the pennation angle of the vastus lateralis muscle (VL) with the performance of an intermittent vertical jumps test. We tested a group of 18 male athletes of the Brazilian Army Confederation of Volleyball. Two longitudinal images of the VL, at 50% of thigh length were acquired with a B-mode ultrasound. Soon after, subjects performed a Counter Movement Jump test to evaluate the maximum vertical jump height. The intermittent vertical jumps test comprised four sets of 15 s maximum jumps. Immediately after, the two images of the pennation angle were again obtained in the same region. Two pennation angle measurements were made in each image, totaling eight measurements per individual. The results of this study showed that there was a significant reduction of the jumps heights (35.77 ± 4.67 cm; 31.94 ± 4.51 cm; 27.04 ± 3.93 cm and 22.60 ± 3 66 cm intervals for 0-15 s, 15-30 s, 30-45 s and 45-60 s, respectively). The VL pennation angle did not present a significant difference before and after the test (12.72 ± 2.26 ° and 13.71 ± 3.40º respectively). The Pearson correlation between the pennation angle measurements before and after the intermittent test and among the heights in all intervals were weak (0.034

Confiabilidade das medidas de arquitetura do músculo Vasto Lateral pela ultrassonografia / Reliability of the measurements of architecture of the Vastus Lateralis muscle by ultrasonography

As medidas de confiabilidade das análises da arquitetura muscular pela ultrasonografia são importantes referências para estudos aplicados de mecânica muscular. O objetivo deste estudo foi determinar a confiabilidade das medidas de espessura muscular (EM), ângulo de penação (AP) e comprimento da fibra (CF) do músculo Vasto Lateral (VL). As imagens de ultrassom foram obtidas em um grupo (N=14; 22 ± 1,75 anos) em duas visitas (sessenta medidas por indivíduo). Foi calculado o coeficiente de correlação intraclasse (CCI), coeficiente de variação (CV) e erro típico da medida (ETM). Os resultados demonstram alta confiabilidade: CCI AP (0,83 a 0,99), EM (0,96 a 0,99) e CF (0,80 a 0,99); CV AP (3,68 a 6,34%), EM (3,12 a 3,84%) e CF (3,98 a 6,33%) e ETM AP (0,18 a 0,59º); EM (0,014 a 0,15mm) e CF (0,07 a 1,47mm). Essas medidas devem ser consideradas em estudos que analisam o impacto na arquitetura muscular em programas de condicionamento do Vasto Lateral.

Reliability of the measurements of the muscle architecture variables by ultrasound are important references for applied studies of muscle mechanics. The aim this study was to analyze the reliability of measurements of Vastus Lateralis (VL) muscle thickness (MT), pennation angle (PA) and fiber length (FL). Ultrasound images were obtained in two days (N=14, 22 ± 1,75 years) with a total of sixty measurements in each subject. Reliability was determined by intraclass correlation coefficient (ICC), coefficient of variation (CV) and typical error of measurement (TEM). Results show high reliability: MT (0,96 a 0,99), PA (0,83 a 0,99) and FL (0,80 a 0,99) ICC; MT (3,12 a 3,84%), PA (3,68 a 6,34%) and FL (3,98 a 6,33%) CV; MT (0,014 a 0,15mm), PA (0,18 a 0,59º) and FL (0,07 a 1,47mm) TEM. These measures should be considered in studies of the impact of conditioning programs in the architecture of the vastus lateralis muscle.

Study on applied anatomy of temporalis / 重庆医学

Objective To investigate the architectural features of temporalis and offer anatomic basis for the clinical application . Methods In eight cadavers ,the gross anatomy ,muscular architecture study of temporalis were performed on anterior ,middle and posterior portion .Results The wet muscle weight of the above portions was (13 .17 ± 3 .41) ,(12 .30 ± 3 .59) ,(9 .68 ± 2 .50)g ;their muscle length was (91 .28 ± 5 .93) ,(100 .15 ± 3 .64) ,(110 .53 ± 6 .18)mm ;and their physiological cross-sectional area in muscle was (485 .90 ± 124 .36) ,(396 .59 ± 110 .05) ,(313 .31 ± 75 .72)mm2 ,respectively .Conclusion These results indicated that the anterior portion of temporalis muscle is designed for tension production ,but the posterior and middle for velocity production .Posterior and middle portion of temporalis muscle could quantifying transfer for the dynamic correction of facial paralysis according to the physio-logical cross-sectional area .

Anatomy and functional architecture of the anconeus muscle / Anatomía y arquitectura funcional del músculo ancóneo

The anconeus is a small muscle situated at the elbow. Although the anconeus is active during elbow extension its importance for the movement is probably small. It could work as an elbow stabilizer. The object of this study was to investigate some anatomic and architectural characteristics of the anconeus, in the hope of shedding light on its function. We studied twenty adult cadaveric specimens. The anconeus originates by the lateral epicondyle of the humerus and inserts along the proximal ulna. The superficial shape of the anconeus is triangular. Tridimensionally the anconeus resembles a hemisected rectangular-based pyramid, with the base at the ulna and apex at the lateral epicondyle. The muscle fibers arise obliquely from the tendinous expansion and inserts at the ulna. Thus, the architecture of the anconeus is penniform, an architecture able to produce more force then displacement. The design index of 0.3 also suggests a force muscle.

El ancóneo es un pequeño músculo situado en la región del codo. Aunque el músculo ancóneo es activo durante la extensión del codo su importancia para este movimiento es probablemente pequeña. Podría actuar como estabilizador del codo. El objetivo de este trabajo fue investigar algunas características anatómicas y arquitectónicas del músculo ancóneo, con la esperanza de lanzar una cierta luz en su función. Estudiamos 20 cadáveres de adultos. El músculo ancóneo se origina al lado del epicóndilo lateral y se inserta en la ulna. La forma superficial del músculo ancóneo es triangular. Tridimensionalmente, el músculo ancóneo se asemeja a la mitad de una pirámide de base rectangular, con la base en la ulna y el ápice lateral al epicóndilo lateral. Sus fibras musculares describen un trayecto oblicuo con una extensión tendinosa que se insertan en la ulna. Por lo tanto, la arquitectura del músculo ancóneo es peniforme, una arquitectura conveniente para producir mayor fuerza con el desplazamiento. El índice de diseño de 0,3 también lo sugiere como un músculo de fuerza.

The innervation,muscle architecture and their clinical application in pectoralis major / 重庆医科大学学报

Objective:To provide anatomical basis for clinical application of human pectoralis major (P.major).Methods:The intramuscular nerve branches and muscle architectural features of P.major were dissected and observed.Results:1.The clavicular part(clavic.part) and sternal part of P.major had their anatomically distinct nerve supply.Some final terminal branches went along their course to each muscle slip.2.The average muscle mass,muscle length,fiber length and cross sectional area of the clavic.part of P.major were 45.9?10.8g,18.5?2.1cm,10.7?1.4cm and 4.1?1.1cm2,respectively and those of sternal part of P.major were 220.4?44.3g,21.4?1.6cm,17.2?2.6cm, 12.4?3.1cm2,respectively.Conclusion:1.P.major could be divided into clavic.part and sternal part compartments according to the intramuscular nerve branches.2.The force produced by sternal part is 3 times as much as the clavic.part and the excursion produced by the former is 1.6 times as much as the latter.The two compartrnents of P.major could be used for muscle transplant respectively,so could each muscle slip.

Architectural properties and specific tension of human knee extensor and flexor muscles based on magnetic resonance imaging / 体力科学

The physiological cross-sectional area (PCSA) of knee extensors (KE) and flexors (KF) was determined using magnetic resonance imaging (MRI) in humans. Twenty two healthy male volunteers were assigned to the subjects and MRI was taken to obtained 41-52 consecutive axial images (slice thickness ; 10 mm, interslice gap ; 0 mm) from right-leg thigh. From these images, anatomical cross-sectional area (ACSA) of KE and KF was determined. Muscle volume was calculated from the summation of each ACSA and the distance between each section. Muscle length was determined as the distance from most proximal to most distal images in which the muscle visible. The PCSA of each muscle was calculated as muscle volume times the cosine of the angle of fiber pinnation divided by fiber length, where published fiber length : muscle length ratio were used to estimate fiber length. The isokinetic knee extension and flexion (angular velocity ; 30, 60, 180, 300, 450 deg/sec) was measured to estimate the muscle force at KE and KF. Specific tension of KE and KF was calculated muscle force deviled by PCSA. The mean muscle volume of KE and KF was 2178, 1141 cm<SUP>3</SUP>. The ratio of KE : KF was 2.6. The mean fiber length in KE was 7-8 cm, and in KF was 6-42 cm. Peak torque during knee extension was significantly higher than knee flexion at all angular velocities. The specific tension of KF was higher than that of KE at all tendon velocities. Moreover, relationships between specific tension and tendon velocity/fiber length, KF was still higher than that of KE. These results suggest that the capacity of tension development differ between KE and KF under the same shortening velocity per unit of sarcomere.

THE DISTRIBUTION OF INTRAMUSCULAR NERVESIN DIFFERENT SKELETAL MUSCLES OF THE RABBIT / 解剖学报

Objective To investigate the distribution of intramuscular nerves in the different skeletal muscles of the rabbit. Methods Muscle architecture and modified sihler's neural staining methods were used. Results The nerve branches of innervating flat M.pectoralis major arose from the anterior pectoral and posterior pectoral nerve.The former innervated cross fibers mainly,it penetrated the middle of muscle belly and formed a “U-Shaped” nerve ansa.The latter innervated oblique fibers mainly.There were many anastomoses between them.The nerve of pennate M.plantaris derived from tibial nerve.After entering muscle,the nerve trunk gradually divided into many primary branches toward medial and lateral fibers,these branches then subdivided into numerous arboroid second and terminal branches toward all of muscle fibres;The nerve of innervating spindle M.extensor digitorum longus came from N.fibularis communis.Two extramuscular nerve trunk were seen.Superior trunk mainly innervated those muscle fibers of inserting in the second toe,Inferior one mainly distributed to the fibers of rest within this muscle.Conclusion The spatial arrangement of the muscle fibres were related to distribution of the intramuscular nerves;Walking of intramuscular nerve branches had two patterns which run perpendicular and/or parallel to muscle fasciculi.