Muscle structure and function in the goose, quail, pheasant, guinea hen, and chicken.

1. Metabolic functions, fiber composition and, in some cases, mitochondrial morphology have been investigated in the pectoralis major and sartorius of the goose, quail, pheasant, guinea-hen, broiler chicken and laying hen. 2. In the pectoralis only two types of fibers, red and white twitch fibers, are found in all birds studied except in the quail, where a third twitch fiber also occurs. Red fibers form the main part in the quail and goose, white fibers in the rest. In the sartorius at least three types of fibers, two twitch and one tonus are found in all birds except in the guinea-hen where only two fibers can be found. 3. The metabolic pattern of the muscles, based on determination of specific activities of metabolic key enzymes, varies greatly among the birds. Three groups can be discerned from the ratio between aerobic and anaerobic activities or between fatty acid oxidation and carbohydrate metabolism. The metabolic patterns are reflected in the fiber combinations of the muscles. 4. The size and number of the mitochondria vary among different animals and different fiber types. The metabolism of red and white fibers is discussed.     

Respiratory muscle activity during vocalization in the squirrel monkey.

In order to find out which muscles are involved in the respiratory component of primate phonation, the activity of 17 abdominal and thoracic muscles was recorded during vocalization in the squirrel monkey. Vocalization-correlated activity was found in the musculi obliquus externus et internus, rectus et transversus abdominis, intercostalis externus et internus and intercartilagineus. It was lacking in the mm. iliocostalis, latissimus dorsi, longissimus dorsi rhomboideus, serratus posterior superior, trapezius, splenius capitis, sternocleidomastoideus, scalenus medius and pectoralis major. There was simultaneous activation of the rib-raising external and rib-lowering internal intercostal muscles during most vocalizations. It is hence concluded that the intercostals, rather than supporting expiratory efforts, serve to stabilize the thorax, thus providing an anchorage against which the abdominal muscles can act.     

Parallel-fibered muscles transplanted with neurovascular repair into bipennate muscle sites in rabbits.

Experiments were performed on 20 New Zealand White male rabbits. Our hypotheses were that (1) latissimus dorsi (LTD) muscles transplanted into the site of a bipennate rectus femoris (RFM) muscle with neurovascular repair would retain their parallel-fibered structure and (2) the parallel-fibered structure of latissimus dorsi grafts would reduce their total fiber cross-sectional area and adversely affect force development relative to that of bipennate rectus femoris grafts and muscles. Compared with their respective donor muscles, 120 to 150 days after grafting, latissimus dorsi and rectus femoris grafts showed no change in the number of fibers and a decrease in the mean single-fiber cross-sectional area to approximately 70 percent. The latissimus dorsi grafts, which remained parallel-fibered, developed maximum forces 34 and 23 percent of the values for fully activated rectus femoris grafts and muscles, respectively. The deficit in the maximum force of the latissimus dorsi grafts resulted primarily from the smaller total-fiber cross-sectional area as a result of the parallel-fibered structure.     

Muscle development in the abdominal region of Larval Hylidae (Amphibia: Anura)

Larval muscle development in the abdominal region of five species of hylid frogs (Scinax nasicum, S. fuscovarium, Hyla andina, Phyllomedusa boliviana, Gastrotheca gracilis) was studied using differential staining techniques. These five species represent three major hylid subfamilies. The development of the main abdominal muscles, the rectus abdominis, the two lateral muscles (obliquus externus and transversus), and the lateral pectoralis abdominalis is described. The number of myotomes of the rectus abdominis varies between five and six, and the abdominal muscles associated with the rectus abdominis (obliquus externus, pectoralis abdominalis, and rectus cervicis) vary interspecifically in time of appearance and configuration. The presence of gaps in the configuration of the rectus abdominis has been related to the lotic habits of the larvae. However, our observations indicate the presence of such gaps in larvae that inhabit lentic environments as well. These results suggest that the presence of these gaps is unrelated to larval habitat. There are relatively small differences in muscle morphology among these closely related species, which apparently cannot be explained by morphological adaptations related to their ecology. In the species studied, the number of elements that form the abdominal musculature in larvae is equal to that observed in adults. Likewise, the general morphology of the muscles is ontogenetically conserved. This suggests that both the axial skeleton and musculature are more ontogenetically conserved in relation to the substantial changes that are observed in the skull and head muscles of developing anurans. J. Morphol. 241:275–282, 1999. © 1999 Wiley‐Liss, Inc.     

The extracellular space of voluntary muscle tissues

The volume occupied by the extracellular space has been investigated in six types of voluntary muscles: sartorius (frog), semitendinosus (frog), tibialis anticus longus (frog), iliofibularis (frog), rectus abdominis (frog), and diaphragm (rat). With the aid of four types of probe material, three of which are conventionally employed (inulin, sorbitol, sucrose) and one of which is newly introduced (poly-L-glutamate), and a different experimental method, we have demonstrated that the "true" extracellular space of frog sartorius, semitendinosus, tibialis anticus longus, and iliofibularis muscle and of rat diaphragm muscle is equal to, or probably less than, 8-9% (v/w) of the tissue. The frog rectus muscle shows a somewhat higher ceiling value of 14%.     

Colour differences among carcasses graded with similar score for conformation and fatness

In a population of 268 yearling bulls, those carcasses graded as U-, U0 or U+ for beef carcass conformation (n = 240) and those graded as 2-, 20 or 2+ for beef carcass fatness (n = 213) were selected to study the efficiency of carcass weight, carcass dimensions and instrumental colour of latissimus dorsi, rectus abdominis and subcutaneous fat, to discriminate among these carcass grades, in a population of high-muscled and very lean carcasses from young bulls. The increase in conformation grade meant an increase in carcass weight and perimeter of the leg. Classifiers use attributes characterizing muscular development and carcass profiles from a general impression of the whole carcass. There were no significant differences for carcass weight or carcass dimensions, among the carcasses classified according to the three fat classes. The a* and b* coordinate values for the latissimus dorsi muscle were observed to decrease significantly as the carcass conformation score increased (P < 0.05). However, muscle and subcutaneous fat of fatter carcasses showed higher a*, b* colour coordinates and chroma (C*) values than leaner carcasses. The CIE (Commission International de l'éclairage) L*, a* and b* colour coordinate measurements taken on the carcasses 45 min post mortem varied significantly from the readings taken after hanging for 24 h (P < 0,001). The higher a* and b* values on the carcasses chilled for 24 h could be caused by oxygenation of both subcutaneous fat, and latissimus dorsi and rectus abdominis muscles in the time elapsing after slaughter and after carcass exposition to circulating air in the cooler for 24 h. Lightness of the latissimus dorsi muscle underwent a decrease, compared with an increase in the rectus abdominis muscle. Hardening of the subcutaneous fat during cold storage may exert an influence on the decrease in lightness observed. These differences in carcass colour during chilling storage would suggest that the relationship between carcass colour and conformation grades was higher shortly after slaughter. Both L* colour coordinate of fat colour (P < 0.01) and a*, b* and C* colour coordinates of latissimus dorsi muscle (P < 0.05) were related to conformation classification. Colour was more efficient to differentiate conformation than fat cover classes. Sixty-two percent of carcasses were correctly classified for conformation by colour differences but only 37% of carcasses were correctly classified for fatness by colour.     

Costochondritis: pathogenesis, diagnosis, and management considerations

The management of costochondritis of the chest wall is reviewed and four illustrative cases presented. Adequate debridement is the single most important factor to ensure eradication of this disease. Well-vascularized tissue coverage reduces ischemic factors, resists secondary infection by contamination, and promotes rapid healing. The pectoralis major, latissimus dorsi, and rectus abdominis muscle flaps are the primary choices for pedicle-flap coverage. Antibiotic coverage was not extended beyond 3 weeks in these cases, and no recurrences have been noted over a 1- to 3-year follow-up.     

Inspiratory and expiratory patterns of the pectoralis major muscle during pulmonary defensive reflexes

Experiments wereconducted to determine the discharge pattern of the pectoralis majormuscle during pulmonary defensive reflexes in anesthetized cats(n = 15). Coughs andexpiration reflexes were elicited by mechanical stimulation of theintrathoracic trachea or larynx. Augmented breaths occurredspontaneously or were evoked by the same mechanical stimuli.Electromyograms (EMGs) were recorded from the diaphragm, rectusabdominis, and pectoralis major muscles. During augmented breaths, thepectoralis major had inspiratory EMG activity similar to that of thediaphragm, but during expiration reflexes the pectoralis major also hadpurely expiratory EMG activity similar to the rectus abdominis. Duringtracheobronchial cough, the pectoralis major had an inspiratory patternsimilar to that of the diaphragm in 10 animals, an expiratory patternsimilar to that of the rectus abdominis in 3 animals, and a biphasicpattern in 2 animals. The pectoralis major was active during both the inspiratory and expiratory phases during laryngeal cough. We conclude that, in contrast to the diaphragm or rectus abdominis muscles, thepectoralis major is active during both inspiratory and expiratory pulmonary defensive reflexes.

     

Fibre types in primary ‘flight’ muscles of the African Penguin (Spheniscus demersus)

The African penguin (Spheniscus demersus) is an endangered seabird that resides on the temperate southern coast of Africa. Like all penguins it is flightless, instead using its specialized wings for underwater locomotion termed ‘aquatic flight’. While musculature and locomotion of the large Antarctic penguins have been well studied, smaller penguins show different biochemical and behavioural adaptations to their habitats. We used histochemical and immunohistochemical methods to characterize fibre type composition of the African penguin primary flight muscles, the pectoralis and supracoracoideus. We hypothesized the pectoralis would contain predominantly fast oxidative–glycolytic (FOG) fibres, with mainly aerobic subtypes. As the supracoracoideus and pectoralis both power thrust, we further hypothesized these muscles would have a similar fibre type complement. Our results supported these hypotheses, also showing an unexpected slow fibre population in the deep parts of pectoralis and supracoracoideus. The latissimus dorsi was also examined as it may contribute to thrust generation during aquatic flight, and in other avian species typically contains definitive fibre types. Unique among birds studied to date, the African penguin anterior latissimus dorsi was found to consist mainly of fast fibres. This study shows the African penguin has specialized flight musculature distinct from other birds, including large Antarctic penguins.     

Metabolic types of muscle in the sheep: I. Myosin ATPase, glycolytic, and mitochondrial enzyme activities

The metabolic characteristics of 12 skeletal muscles of the sheep were studied. Glycolytic activities (hexokinase, glycogen synthetase I and D, phosphorylase a and b, phosphofructokinase) were measured. Myofibrillar ATPase activity was evaluated. Oxygen consumption, respiratory control and carnitine palmityl transferase, isocitrate dehydrogenase, succinate dehydrogenase and cytochrome oxidase activities were measured in isolated mitochondria. Three metabolic types could be distinguished; (1) essentially oxidative slow twitch muscles, typified by the supraspinatus and infraspinatus, having low ATPase activity, (2) fast twitch red muscles, typified by the longissimus dorsi and the semimembranosus, having a higher ATPase activity and both high oxidative and high glycolytic activity, and (3) essentially glycolytic fast twitch muscles, typified by the tensor fascia lata and the semitendinosus, having the highest ATPase activity.     

Increased trunk muscle recruitment during the golf swing is linked to developing lower back pain: A prospective longitudinal cohort study

BackgroundThis is the first study that presents electromyographic measurements prior to the development of lower back pain in young elite golfers.Study designProspective longitudinal cohort study.MethodsThirty-three injury free elite golfers were included. Muscle activity from latissimus dorsi, rectus abdominis, external oblique and erector spinae muscles were recorded during 10 drive golf swings. Lower back pain, training and performance were monitored over a six-month period. Muscle activation comparisons were made between the baseline results of those who went on to develop lower back pain versus those who did not go on to develop lower back pain.ResultsAfter the six-month monitoring period 17 participants developed lower back pain. The group that developed lower back pain had increased dominant rectus abdominis and dominant latissimus dorsi activation at various time points throughout the swing.DiscussionThe increased dominant rectus abdominis and dominant latissimus dorsi during the golf swing is linked with developing lower back pain. Training strategies aimed at reducing these muscles activation during the swing may reduce the incidence of lower back pain in young elite male golfers.     

Shoulder muscle EMG activity during push up variations on and off a Swiss ball

Background

Surface instability is a common addition to traditional rehabilitation and strength exercises with the aim of increasing muscle activity, increasing exercise difficulty and improving joint proprioception. The aim of the current study was to determine if performing upper body closed kinetic chain exercises on a labile surface (Swiss ball) influences myoelectric amplitude when compared with a stable surface.

Methods

Thirteen males were recruited from a convenience sample of college students. Surface electromyograms were recorded from the triceps, pectoralis major, latissimus dorsi, rectus abdominis and external oblique while performing push up exercises with the feet or hands placed on a bench and separately on a Swiss ball. A push up plus exercise was also evaluated with hands on the support surface.

Results and discussion

Not all muscles responded with an increase in muscle activity. The pectoralis major muscle was not influenced by surface stability. The triceps and rectus abdominis muscles showed increases in muscle activity only when the hands were on the unstable surface. The external oblique muscle was only influenced by surface stability during the performance of the push up plus exercise. No muscle showed a change in activation level when the legs were supported by the Swiss ball instead of the bench.

Conclusion

Muscle activity can be influenced by the addition of surface instability however an increase in muscle activity does not influence all muscles in all conditions. The relationship between the participant's center of mass, the location of the unstable surface and the body part contacting the Swiss ball may be important factors in determining the muscle activation changes following changes in surface stability.

     

EMG power spectra of trunk muscles during graded maximal voluntary isometric contraction in flexion-rotation and extension-rotation

The purpose of this study was to determine the electromyographic (EMG) power spectral characteristics of seven trunk muscles bilaterally during two complex isometric activities extension-rotation and flexion-rotation, in both genders to describe the frequency-domain parameters. Eighteen normal young subjects volunteered for the study. The subjects performed steadily increasing isometric extension-rotation and flexion-rotation contractions in a standard trunk posture (40 degrees flexed and 40 degrees rotated to the right). A surface EMG was recorded from the external and internal oblique, rectus abdominis, pectoralis, latissimus dorsi, and erector spinae muscles at the 10th thoracic and the 3rd lumbar vertebral levels, at 1 kHz and 25%, 50%, 75% and 100% of maximal voluntary contraction (MVC). The median frequency (MF), mean power frequency (MPF), frequency spread and peak power were obtained from fast Fourier transform analysis. The MF and MPF for both extension-rotation and flexion-rotation increased with the grade of contraction for both males and females. The EMG spectra in flexion-rotation were different from those of extension-rotation (P < 0.001). The left external and right internal oblique muscles played the role of antagonists in trunk extension-rotation. There was an increase in the MF of the trunk muscles with increasing magnitude of contraction. Frequency-domain parameters for both the male and female subjects were significantly different (P < 0.001).     

Characterization of the C-protein from posterior latissimus dorsi muscle of the adult chicken: heterogeneity within a single sarcomere

Specific isoforms of myofibrillar proteins are expressed in different muscles and in various fiber types within a single muscle. We have isolated and characterized monoclonal antibodies against C-proteins from slow tonic (anterior latissimus dorsi, ALD) and fast twitch (pectoralis major) muscles of the chicken. Although the antibody against "fast" C-protein (MF-1) did not bind to the "slow" isoform and the antibody to the "slow" C-protein (ALD-66) did not bind to the "fast" isoform, we observed that both antibodies bound C-protein from the posterior latissimus dorsi (PLD) muscle. Here we demonstrate that in the PLD muscle the binding sites of these two antibodies reside in two different C-protein isoforms which have different molecular weights and can be separated by hydroxylapatite column chromatography. Since we have shown previously that both these antibodies stain all myofibers and myofibrils derived from PLD muscle, we conclude that all myofibers in this muscle contain both isoforms with all sarcomeres.     

Electromyography of trunk muscles in isometric graded axial rotation.

This study was conducted to determine the pattern, magnitude, and phasic inter-relationship of the trunk muscles in maximal isometric and graded isometric axial rotational contractions and compare them with those previously observed from the same subjects in the same experimental session in dynamic conditions. In 50 normal young healthy subjects (27 male and 23 female), after a suitable skin preparation, bipolar silver-silver chloride recessed pregelled surface electrodes were placed on external oblique, internal oblique, rectus abdominis, pectoralis major, latissimus dorsi, erector spinae at T(10) and L(3) levels bilaterally with 2 cm interelectrode distance. EMG signals from grounded subjects were suitably preamplified and amplified by a fully isolated system. These subjects were stabilized in an upright-seated posture in the Axial Rotation Tester (AROT), which was placed in isometric mode for force and rotation output from the AROT. The 14 channels of EMG, the force and the rotation were sampled at 1 kHz. The subjects initially registered their isometric maximal voluntary contraction (MVC) on both sides which was used for reference and then performed their 25%, 50% and 75% of MVC bilaterally in an isometric mode in a random order. The EMG magnitude, the slope of the rise of the EMG, and the phasic interrelationship of muscles were analyzed. The results showed that female sample generated only 65% of torque of their male counterparts. There were no significant differences between the male and the female samples in the EMG variables. Exertions to the left and to the right were not significantly different from each other for the measured variables. However, the magnitude contribution of the muscles and the slope of rise of EMG were significantly different in two directions (p<0.001). The phasic interrelationship of the external obliques, the latissimus dorsi and the erector spinae were different from other muscles (p<0.01). With the increasing grades of contraction the latissimus dorsi and the external obliques increased their magnitude significantly whereas that of the erectores spinae underwent a decrease in proportionate terms (but not in absolute magnitude) suggesting their role as stabilizers but not as rotators.     

Effects of the pullover exercise on the pectoralis major and latissimus dorsi muscles as evaluated by EMG

The aim of the current study was to investigate the EMG activity of pectoralis major and latissimus dorsi muscles during the pullover exercise. Eight healthy male volunteers took part in the study. The EMG activity of the pectoralis major and that of the latissimus dorsi of the right side were acquired simultaneously during the pullover exercise with a free-weight barbell during both the concentric and eccentric phases of the movement. After a warm-up, all the subjects were asked to perform the pullover exercise against an external load of 30% of their body weight, during 1 set × 10 repetitions. The criterion adopted to normalize the EMG data was the maximal voluntary isometric activation. The present findings demonstrated that the barbell pullover exercise emphasized the muscle action of the pectoralis major more than that of the latissimus dorsi, and the higher activation depended on the external force lever arm produced.     

Immunocytochemical localization of aldolase in normal, denervated, and dystrophic chicken muscles

To investigate whether immunocytochemical localization of muscle-specific aldolase can be used for fiber phenotype determination, we produced specific antibodies against the enzyme and studied its distribution in adult chicken skeletal muscles by indirect immunofluorescence microscopy. Monoclonal antibodies against the myosin heavy chains of fast-twitch (MF-14) and slow-tonic (ALD-58) muscle fibers were also used to correlate aldolase levels with the fiber phenotype. The goat anti-aldolase antibody was found to be specific for the A form of aldolase, as evidenced by sodium dodecyl sulfate gel electrophoresis, immunotitration experiments, and immunoblot analysis. The antibody reacted strongly with the fast-twitch myofibers of normal pectoralis and posterior latissimus dorsi muscles; the phenotype of these muscle fibers was confirmed by a positive immunofluorescent reaction after incubation with MF-14 antibody. By contrast, the slow-tonic myofibers of normal anterior latissimus dorsi, which react positively with ALD-58 antibody, reacted weakly with anti-aldolase antibodies. In denervated chicken muscles, reaction to anti-aldolase antibodies was markedly reduced in fast-twitch fibers, although reaction to MF-14 was not diminished. By contrast, in dystrophic muscle, fast-twitch fibers showed reduced reactivity to anti-aldolase and marked to moderate reduction in MF-14 reactivity. Our results show that: (a) in normal muscles, reactivity to anti-aldolase matches the phenotype obtained by using anti-fast or anti-slow myosin heavy chain antibodies, and therefore can serve to identify mature fibers as fast or slow; and (b) in denervated or dystrophic muscles, the intracellular expressions of aldolase and fast-twitch myosin heavy chains are regulated independently.     

Myosin heavy chains from two different adult fast-twitch muscles have different peptide maps but identical mRNAs

Myosin heavy chains prepared from the pectoralis major and from the posterior latissimus dorsi of the same adult chicken exhibit different peptide maps when cleaved with Staphylococcus aureus V8 protease. These differences were observed at five different enzyme concentrations and in chickens of various strains. The cleavage pattern of pectoralis major myosin heavy chain from different adult chickens was always identical, as was that of posterior latissimus dorsi myosin heavy chain, demonstrating the reproducibility of the technique. However, when RNAs extracted from the pectoralis major and from the posterior latissimus dorsi were translated in a cell-free reticulocyte lysate, the myosin heavy chain encoded by pectoralis major RNA and the myosin heavy chain encoded by posterior latissimus dorsi RNA exhibited identical peptide maps. These results suggest that the different peptide maps of myosin heavy chains from the pectoralis major and posterior latissimus dorsi may arise from posttranslational modifications.     

Ultrastructural features of neuromuscular junctions in the stapedius muscle of Gallus gallus

The ultrastructure of neuromuscular junctions in the twitch fibers of the stapedius muscle of Gallus gallus (domesticus) was investigated as part of a series of neurophysiological studies. Among the morphological features observed were elongated end-plates with numerous large and clear synaptic vesicles mixed with larger dense core vesicles and irregular or aperiodic “active sites” in the presynaptic membrane where synaptic vesicles were focused. The most remarkable features of these junctions were large synaptic clefts (50-80 nm) and the absence of junctional folds in the sarcolemmal surface. Unlike the large periodic junctional folds seen in the neuromuscular junctions of frogs and in the fast twitch fibers of the mammalian stapedius, the preparations studied only show small aperiodic invaginations (primitive folds) in the postsynaptic membranes. This morphological feature remains essentially constant from newly hatched to adult chickens. While these smooth junctions are consistent with earlier findings of inconspicuous junctional folds in the twitch fibers of the chicken posterior latissimus dorsi they are unlike those seen in the fast twitch fibers of the mammalian stapedius muscle, or other twitch fibers in general. The morphological findings of the present study may also suggest that the simple, unmodified neuromuscular junctions in the stapedius of Gallus may be a useful preparation for studies of synaptic membrane structures that employ the freeze-fracture technique.     

Preliminary electromyographical analysis of brachiation in gibbon and spider monkey

In order to refine the concept of brachiation as a locomotor mode and to examine the complex relationship between locomotor behavior and muscle morphology, we have undertaken a telemetered electromyographic (EMG) analysis of muscle recruitment in brachiating gibbons (Hylobates lar) and spider monkeys (Ateles belzebuth andAteles fusciceps) Electrical activity patterns were determined for both support and swing phases in the following muscles: cranial pectoralis major, caudal pectoralis major, middle deltoideus, short head of biceps brachii, flexor digitorum superficialis, latissimus dorsi, and dorsoepitrochlearis. Our experimental findings reinforce earlier behavioral observations that brachiation is not a discrete, stereotyped locomotor activity. EMG patterns differed most between gibbon and spider monkey in those muscles that exhibit markedly disparate morphologies in the two genera-pectoralis major (both portions) and the short head of biceps brachii. Additional recruitment differences appear related to consistent species-specific differences in the timing and mechanics of both support and swing phases, and probably to the role of the prehensile tail as a fail-safe mechanism in the spider monkey.