scholarly journals Development of Postural Muscles and Their Innervation

2005 ◽  
Vol 12 (2-3) ◽  
pp. 141-151 ◽  
Author(s):  
J. IJkema-Paassen ◽  
A. Gramsbergen
Keyword(s):  
Motor Performance ◽  
Muscle Fibers ◽  
Animal Experiments ◽  
Great Resistance ◽  
Fiber Properties ◽  
Flexor Muscles ◽  
Dendrite Bundles ◽  
Arm Muscles ◽  
Muscle Actions ◽  
Postural Muscles

Control of posture is a prerequisite for efficient motor performance. Posture depends on muscles capable of enduring contractions, whereas movements often require quick, forceful muscle actions. To serve these different goals, muscles contain fibers that meet these different tasks. Muscles with strong postural functions mainly consist of slow muscle fibers with a great resistance against fatigue. Flexor muscles in the leg and arm muscles are mainly composed of fast muscle fibers producing relatively large forces that are rapidly fatigable. Development of the neuromuscular system continues after birth. We discuss in the human baby and in animal experiments changes in muscle fiber properties, regression from polyneural into mononeural innervation, and developmental changes in the motoneurons of postural muscles during that period. The regression of poly-neural innervation in postural muscles and the development of dendrite bundles of their motoneurons seem to be linked to the transition from the immature into the adult-like patterns of moving and postural control.

Ultrastructural characterization of superficial and deep flexor muscles in the crayfish thorax

1981 ◽  
Vol 59 (3) ◽  
pp. 357-363 ◽  
Author(s):  
R. L. Crabtree ◽  
R. G. Sherman
Keyword(s):  
Muscle Fibers ◽  
Longitudinal Axis ◽  
Flexor Muscle ◽  
Ultrastructural Characterization ◽  
Flexor Muscles

Transmission electon microscopy revealed that all of the superficial flexor muscle fibers in the crayfish thorax possess sarcomeres 8–10 μm in length, 12 thin myofilaments around each thick myofilament, no H zone, and irregular Z lines. This characterizes them as tonic. All of the deep flexor fibers possess sarcomeres 2–4 μm in length, six myofilaments around each thick myofilament, a distinct H zone, and Z lines that are perpendicular to the longitudinal axis of the fiber. This characterizes them as phasic. Differences in the distribution of mitochondria and glycogen granules and in the organization of synaptic regions also are noted.

scholarly journals Repression of slow myosin heavy chain 2 gene expression in fast skeletal muscle fibers by muscarinic acetylcholine receptor and Gαq signaling

2003 ◽  
Vol 162 (5) ◽  
pp. 843-850 ◽  
Author(s):  
Theresa Jordan ◽  
Jinyuan Li ◽  
Hongbin Jiang ◽  
Joseph X. DiMario
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Acetylcholine Receptor ◽  
Muscle Fibers ◽  
Muscarinic Acetylcholine Receptor ◽  
Fast Skeletal Muscle ◽  
Muscarinic Acetylcholine ◽  
Fiber Properties ◽  
Skeletal Muscle Fibers ◽  
Slow Myosin Heavy Chain

Gene expression in skeletal muscle fibers is regulated by innervation and intrinsic fiber properties. To determine the mechanism of repression of slow MyHC2 expression in innervated fast pectoralis major (PM) fibers, we investigated the function of the muscarinic acetylcholine receptor (mAchR) and Gαq. Both mAchR and Gαq are abundant in medial adductor (MA) and PM fibers, and mAchR and Gαq interact in these fibers. Whereas innervation of PM fibers was insufficient to induce slow MyHC2 expression, inhibition of mAchR activity with atropine in innervated PM fibers induced slow MyHC2 expression. Increased Gαq activity repressed slow MyHC2 expression to nondetectable levels in innervated MA fibers. Reduced mAchR activity decreased PKC activity in PM fibers, and increased Gαq activity increased PKC activity in PM and MA fibers. Decreased PKC activity in atropine-treated innervated PM fibers correlated with slow MyHC2 expression. These data suggest that slow MyHC2 repression in innervated fast PM fibers is mediated by cell signaling involving mAchRs, Gαq, and PKC.

External hydrocephalus in adults

1996 ◽  
Vol 85 (6) ◽  
pp. 1143-1147 ◽  
Author(s):  
érico R. Cardoso ◽  
Romaine Schubert
Keyword(s):  
Cerebrospinal Fluid ◽  
Ventriculoperitoneal Shunt ◽  
Animal Experiments ◽  
Great Resistance ◽  
Posthemorrhagic Hydrocephalus ◽  
Content Type ◽  
External Hydrocephalus ◽  
Csf Shunting ◽  
Fluid Collections ◽  
Fine Print

✓ The authors report three adult patients who developed a symptomatic extraaxial collection of cerebrospinal fluid (CSF) after an intracranial hemorrhage. The fluid shifted from the extraaxial into the ventricular space as the patients' symptoms progressed. The symptoms resolved after placement of a ventriculoperitoneal shunt. External hydrocephalus, which is frequently observed in children, had not yet been described in adults. It is important to differentiate chronic subdural collections from external hydrocephalus, because ventricular CSF shunting increases the former while it is the treatment for the latter. The authors believe that symptomatic extraaxial fluid collections developed in these three adults during the early phase of posthemorrhagic hydrocephalus because the ventricles presented great resistance to distention at the onset of hydrocephalus. Animal experiments have led to the same result.

scholarly journals A COMPARATIVE STUDY ON THE FINE STRUCTURE OF THE BASALAR MUSCLE OF THE WING AND THE TIBIAL EXTENSOR MUSCLE OF THE LEG OF THE LEPIDOPTERAN ACHALARUS LYCIADES

1967 ◽  
Vol 33 (3) ◽  
pp. 531-542 ◽  
Author(s):  
J. F. Reger ◽  
D. P. Cooper
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Flight Muscle ◽  
Muscle Fibers ◽  
Extensor Muscle ◽  
Insect Muscle ◽  
Hexagonal Packing ◽  
Electron Microscopes ◽  
Fast Acting ◽  
Postural Muscles ◽  
T System

Basalar and tibial extensor muscle fibers of Achalarus lyciades were examined with light and electron microscopes. Basalar muscle fibers are 100–150 µ in diameter. T-system membranes and sarcoplasmic reticulum make triadic contacts midway between Z lines and the middle of each sarcomere. The sarcoplasmic reticulum is characterized by a transverse element situated among myofilaments halfway between Z lines in every sarcomere. The morphology of Z lines, hexagonal packing of thin and thick myofilaments, and thin/thick myofilament ratios are similar to those of fast-acting insect muscles. Tibial extensor muscle fibers are 50–100 µ in diameter. Except for a lack of the transverse element, the T system and sarcoplasmic reticulum are similar to those of basalar muscle. Wavy Z lines, lack of a hexagonal packing of myofilaments, and larger thin/thick myofilament ratios are similar to those of other postural muscles of insects. The morphology of basalar and tibial extensor muscle is compared to that of other insect muscle with known functions, and reference is made to the possible contribution of the transverse element of sarcoplasmic reticulum in basalar flight muscle to speed and synchrony in this muscle.

scholarly journals EXPRESS: Getting a Handle on Sales: Shopping Carts Affect Purchasing by Activating Arm Muscles

2021 ◽  
pp. 002224292110613
Author(s):  
Zachary Estes ◽  
Mathias C. Streicher
Keyword(s):  
Field Experiment ◽  
Physical Properties ◽  
Muscle Activation ◽  
Upper Arm ◽  
Shopping Cart ◽  
Extensor Muscles ◽  
Flexor Muscles ◽  
Arm Muscles

This research demonstrates that the physical properties of shopping carts influence purchasing and spending. Prior research on ergonomics indicates that standard shopping carts, which are pushed via a horizontal handlebar, are likely to activate arm extensor muscles. Prior research on arm muscle activation, in turn, suggests that arm extensor activation may elicit less purchasing than arm flexor activation. The authors thus deduce that standard shopping carts may be suboptimal for stimulating purchases. The authors predicted that shopping carts with parallel handles (i.e., like a wheelbarrow or “walker”) would instead activate the flexor muscles and thus increase purchasing. An electromyography (EMG) study revealed that both horizontal and vertical handles more strongly activate the extensor muscles of the upper arm (triceps), whereas parallel handles more strongly activate the flexor muscles (biceps). In a field experiment, parallel-handle shopping carts significantly and substantially increased sales across a broad range of categories, including both vice and virtue products. Finally, in a simulated shopping experiment, parallel handles increased purchasing and spending beyond both horizontal and vertical handles. These results were not attributable to the novelty of the shopping cart itself, participants’ mood, or purely ergonomic factors.

Crosstalk in Mechanomyographic Signals From Elbow Flexor Muscles During Submaximal to Maximal Isometric Flexion, Pronation, and Supination Torque Tasks

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Irsa Talib ◽  
Kenneth Sundaraj ◽  
Chee Kiang Lam
Keyword(s):  
Biceps Brachii ◽  
Elbow Flexion ◽  
Fiber Axis ◽  
Maximum Voluntary Isometric Contraction ◽  
High Positive Correlation ◽  
Flexor Muscles ◽  
Positive Correlations ◽  
Muscle Actions ◽  
Level Of Effort ◽  
Isometric Muscle

Abstract This study analyzed the crosstalk in mechanomyographic (MMG) signals from elbow flexors during isometric muscle actions from 20% to 100% maximum voluntary isometric contraction (MVIC). Twenty-five young, healthy, male participants performed the isometric elbow flexion, forearm pronation, and supination tasks at an elbow joint angle of 90 deg. The MMG signals from the biceps brachii (BB), brachialis (BRA), and brachioradialis (BRD) muscles were recorded using accelerometers. The cross-correlation coefficient was used to quantify the crosstalk in MMG signals, recorded in a direction transverse to muscle fiber axis, among the muscle pairs (P1: BB and BRA, P2: BRA and BRD, and P3: BB and BRD). In addition, the MMG RMS and MPF were quantified. The mean normalized RMS and mean MPF exhibited increasing (r > 0.900) and decreasing (r < −0.900) trends, respectively, with increases in the effort levels in all three tasks. The magnitude of crosstalk ranged from 0.915% to 21.565% in all three muscle pairs. The crosstalk was found to exhibit high positive correlations with submaximal to maximal flexion [P1 (r = 0.970), P2 (r = 0.951), and P3 (r = 0.824)], pronation [P1 (r = 0.811), P2 (r = 0.763), and P3 (r = 0.901)] and supination [P1 (r = 0.898), P2 (r = 0.838), and P3 (r = 0.852)] torque levels (eight out of nine p-values were < 0.05). Regardless of the high positive correlation between crosstalk and level of effort, the crosstalk remained at a low range (0.915–21.565%) with increases in the torque levels.

Comparison of physiological and histochemical properties of motor units after cross-reinnervation of antagonistic muscles in the cat hindlimb

1988 ◽  
Vol 60 (1) ◽  
pp. 365-378 ◽  
Author(s):  
T. Gordon ◽  
C. K. Thomas ◽  
R. B. Stein ◽  
S. Erdebil
Keyword(s):  
Muscle Fibers ◽  
Motor Units ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Single Motor Units ◽  
Extensor Muscles ◽  
Flexor Muscles ◽  
The Cross ◽  
Triceps Surae Muscles ◽  
Fast Twitch

1. Physiological and histochemical properties of the cat ankle extensor muscles, the lateral and medial gastrocnemius, and the soleus were studied after cross-reinnervation by flexor motoneurons. 2. Tibial and common peroneal nerves were cut and cross-united in the popliteal fossa of 2- to 6-mo-old cats. Eighteen to 24 mo later, single motor units were isolated by dissection and stimulation of ventral root filaments and classified into four types: fast-twitch, fatigable (FF), fast-twitch with intermediate fatigue resistance (FI), fast-twitch, fatigue-resistant (FR), and slow, fatigue-resistant (S). Muscle fibers were classified as fast glycolytic (FG), fast, oxidative glycolytic (FOG), and slow oxidative (SO) on the basis of histochemical staining. 3. Although motor-unit force was normally well correlated with the size of the innervating motor axon in the cross-reinnervated muscles, the force of different unit types overlapped considerably. The reinnervated motor units also showed a higher than normal degree of fatigability. 4. The range of muscle unit forces in cross-reinnervated triceps surae muscles was the same as in the normally innervated triceps surae muscles. This range is 2-3 times greater than the flexor muscles, which the common peroneal nerve normally supplies. The range of contraction speed of units in the cross-reinnervated extensor muscles was comparable to that in the flexor muscles, consistent with a motoneuron-specific determination of muscle speed (28). 5. SO and FOG muscle fibers were found in all reinnervated triceps surae muscles, but FG fibers were only found in reinnervated medial gastrocnemius (MG) and lateral gastrocnemius (LG) muscles, consistent with previous findings of the resistance of soleus muscles to complete conversion (10, 16, 20, 21). Type grouping of muscle fibers was characteristic of the reinnervated muscles. 6. Reinnervated SO muscle fibers were larger than the corresponding fibers in normally innervated muscles as were the estimated number of muscle fibers innervated by slow motor axons. Nonetheless, the force generated by the S motor units remained relatively smaller than FR and FF units. The relative contributions of the number, cross-sectional area and specific tension to the force generation of reinnervated motor units are discussed.

Expression and functional behavior of troponin C in soleus muscle fibers of rat after hindlimb unloading

2001 ◽  
Vol 90 (3) ◽  
pp. 1095-1101 ◽  
Author(s):  
P. Kischel ◽  
B. Bastide ◽  
L. Stevens ◽  
Y. Mounier
Keyword(s):  
Differential Effect ◽  
Muscle Fibers ◽  
Troponin C ◽  
Hindlimb Unloading ◽  
Skinned Muscle ◽  
Functional Behavior ◽  
Skinned Muscle Fibers ◽  
Regulation Of Muscle Contraction ◽  
Whole Muscle ◽  
Postural Muscles

Troponin C (TnC) plays a key role in the regulation of muscle contraction, thereby modulating the Ca2+-activation characteristics of skinned muscle fibers. This study was performed to assess the effects of a 15-day hindlimb unloading (HU) period on TnC expression and its functional behavior in the slow postural muscles of the rat. We investigated the TnC isoform expression in whole soleus muscles and in single fibers. The latter were also checked for their Ca2+activation characteristics and sensitivity to bepridil, a Ca2+ sensitizer molecule. This drug has been described as exerting a differential effect on slow and fast fibers, depending on the TnC isoform. With regard to TnC expression, three populations were found in control muscle fibers: slow, hybrid slow, and hybrid fast fibers, with the TnC fast being always coexpressed with TnC slow. In the whole muscle, TnC fast expression increased after HU because of the increase in the proportion of hybrid fast fibers. The HU hybrid fast fibers had properties similar to those of control hybrid fast fibers. The fibers that remained slow after HU exhibited similar bepridil and Sr2+ properties as control slow fibers. Therefore, in these fibers, the changes could not be related to the TnC molecule.

Mitochondrial Changes in Choline-Deficient Rat Myocardium

1968 ◽  
Vol 26 ◽  
pp. 112-113
Author(s):  
F. G. Zaki
Keyword(s):  
Muscle Fibers ◽  
Liver Mitochondria ◽  
Ultrastructural Changes ◽  
Choline Deficiency ◽  
Nutritional Disorder ◽  
Low Protein ◽  
Structural Abnormalities ◽  
Cross Striation ◽  
Pericardial Edema ◽  
Myocardial Lesions

Choline-deficiency was induced in Holtzman young rats of both sexes by feeding them a high fat - low protein diet.Preliminary studies of the ultrastructural changes in the myocardium of these animals have been recently reported from this laboratory. Myocardial lesions first appeared in the form of intraventricular mural thrombi, loss of cross striation of muscle fibers and focal necrosis of muscle cells associated with interstitial myocarditis. Prolonged choline-deficiency induced cardiomegaly associated with pericardial edema.During the early phase of this nutritional disorder, heart mitochondria - despite of not showing any swelling similar to that usually encountered in liver mitochondria of the same animal - ware the most ubiquitous site of marked structural abnormalities. Early changes in mitochondria appeared as vacuolation, disorganization, disruption and loss of cristae. Degenerating mitochondria were often seen quite enlarged and their matrix was replaced by whorls of myelin figures resembling lysosomal structures especially where muscle fibers were undergoing necrosis. In some areas, mitochondria appeared to be unusually clumped together where some contained membranelined vacuoles and others enclosed dense bodies and granular inclusions.

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