The organization and activity patterns of the anterior and posterior heads of the guinea pig digastric muscle

1987 ◽  
Vol 58 (3) ◽  
pp. 496-509 ◽  
Author(s):  
A. Lev-Tov ◽  
M. Tal
Keyword(s):  
Guinea Pig ◽  
Activity Patterns ◽  
Motor Nucleus ◽  
Digastric Muscle ◽  
Fiber Types ◽  
Jaw Movements ◽  
Cross Sectional ◽  
Trigeminal Motor Nucleus ◽  
Facial Motor Nucleus ◽  
Early Activity

The structure and activity patterns of the anterior and posterior heads of the guinea pig digastric muscle (DG) were studied in ketamine-anesthetized guinea pigs. Collagen staining of longitudinal and transverse sections of the muscle revealed that the guinea pig DG is comprised of a unicompartmental anterior head (ADG) and a multicompartmental posterior head (PDG). The two heads are separated by a thin tendinous inscription that, unlike the intermediate tendon of the DG in humans, is not attached to the hyoid bone. The motor nuclei of the guinea pig DG were reconstructed using retrograde labeling with horseradish peroxidase. The motoneurons of the ADG were clustered in a longitudinal column within the trigeminal motor nucleus. The motoneurons of the PDG were segregated into two clusters within the facial motor nucleus. The cross-sectional areas of the ADG and PDG motoneuron somata exhibited unimodal frequency distributions and the average soma area was larger for ADG than PDG motoneurons. Histochemical characterization of ADG and PDG revealed that the two muscle heads contained the three main histochemical types of muscle fibers identified in limb muscles. The frequency distribution of fiber types in ADG and PDG were not significantly different. Both muscle heads were predominantly fast with slow oxidative fibers accounting for only 1.1 and 0.3% of the fibers in narrow dorsal regions of ADG and PDG, respectively, and 13.6 and 12.9% in the more ventral regions of ADG and PDG, respectively. Simultaneous recordings of EMGs from the ADG and PDG were carried out during spontaneously occurring rhythmical jaw movements. These recordings revealed a high degree of synchrony between the activities of the two heads, although differences were observed in the onset and duration of the EMG bursts. Activity in the PDG preceded activity in the ADG in most of the rhythmical cycles and persisted longer. The differences in latencies of time-locked EMGs evoked in the ADG and PDG by four-pulse cortical stimulation were much smaller than those observed between the activity bursts of the two heads during rhythmical jaw movements. It is suggested that the early activity in the PDG is accounted for by shorter central conduction times in the pathways onto it and/or by higher recruitability of its motor units. The early activity in PDG may serve to optimize the location of ADG on its length-tension curve prior to and during the active state.

Differential Innervation of Tissues Located at Traditional Acupuncture Points in the Rat Forehead and Face

2018 ◽  
Vol 36 (6) ◽  
pp. 408-414 ◽  
Author(s):  
Jia Wang ◽  
Jingjing Cui ◽  
Chen She ◽  
Dongsheng Xu ◽  
Zhiyun Zhang ◽  
...  
Keyword(s):  
Nervous System ◽  
Sensory Neurons ◽  
Motor Neurons ◽  
Acupuncture Point ◽  
Acupuncture Points ◽  
Motor Nucleus ◽  
Neural Pathways ◽  
Trigeminal Motor Nucleus ◽  
Facial Motor Nucleus ◽  
Neural Tracing

Objectives To compare the neural pathways associated with the tissues located at different traditional acupuncture points in the rat forehead and face using the cholera toxin B subunit (CTB) neural tracing technique. Methods After injection of CTB into the tissues at GB14, ST2 and ST6 in the rat, the neural labelling associated with each acupuncture point was revealed by fluorescent immunohistochemistry of the nervous system, including the trigeminal ganglion (TRG), cervical dorsal root ganglia (DRG), spinal cord and brain. Results The CTB labelling included sensory neurons and their transganglionic axonal terminals, as well as motor neurons. The labelled sensory neurons associated with GB14, ST2 and ST6 were distributed in both the TRG and cervical DRG, and their centrally projected axons terminated in an orderly fashion at their corresponding targets in the spinal trigeminal nucleus and cervical spinal dorsal horn. In addition, labelled motor neurons were observed in the facial motor nucleus, trigeminal motor nucleus and cervical spinal ventral horn, in which facial motor neurons projected to the tissues located at all three acupuncture points. Trigeminal motor neurons innervated both ST2 and ST6, while spinal motor neurons only correlated with ST6. Conclusions These results indicate that the tissues located at each of these three traditional acupuncture points in the rat forehead and face has its own sensory and motor connection with the nervous system in a region-specific pattern through distinct neural pathways. Understanding the neuroanatomical characteristics of acupuncture points from the peripheral nervous system to the central nervous system should help inform acupuncture point selection according to the demands of the clinical situation.

A study of synaptic morphology in the trigeminal motor nucleus utilizing the HRP method

1978 ◽  
Vol 36 (2) ◽  
pp. 588-589
Author(s):  
A. Konishi ◽  
N. Mizuno ◽  
S. Nomura ◽  
K. Itoh ◽  
Y. Nakamura
Keyword(s):  
Single Injection ◽  
Motor Nucleus ◽  
Digastric Muscle ◽  
Synaptic Organization ◽  
Trigeminal Motor Nucleus ◽  
Muscle Belly ◽  
Axon Terminals ◽  
Anterograde Axonal Transport ◽  
Hrp Method ◽  
Adult Cats

The synaptic organization of the motor nucleus of the trigeminal nerve in the cat was examined electron microscopically after labelling the motoneurons or the axon terminals on the motoneurons by retrograde or anterograde axonal transport of horseradish peroxidase (HRP).The experiments were carried out on young adult cats (1. 5 to 3. 0 kg) anesthetized with intraperitoneal Nembutal (35 mg/kg). For labelling the motoneurons, 2% solution of HRP (Toyobo Grade-I-C, RZ: 3. 4) dissolved in sterile 0. 9% saline was injected within the muscle belly of the temporal, masseter or anterior digastric muscle with a fine caliber intradermic needle attached to a syringe. For labelling axon terminals of the commissural fibers arising contralaterally from the commissural interneurons around the trigeminal motor nucleus, a single injection of 0. 05 μ l of 50% HRP dissolved in 2% dimethylsulfoxide or in sterile 0. 9% saline was performed stereotaxically within the trigeminal motor nucleus and its adjacent regions.

Localization of masticatory motoneurons in the trigeminal motor nucleus of the guinea pig

1982 ◽  
Vol 29 (3) ◽  
pp. 219-224 ◽  
Author(s):  
Masanori Uemura-Sumi ◽  
Osamu Takahashi ◽  
Ryotaro Matsushima ◽  
Masahiko Takata ◽  
Yukihiko Yasui ◽  
...  
Keyword(s):  
Guinea Pig ◽  
Motor Nucleus ◽  
Trigeminal Motor Nucleus

Effects of pontomedullary reticular formation stimulation on the neuronal networks responsible for rhythmical jaw movements in the guinea pig

1988 ◽  
Vol 59 (3) ◽  
pp. 819-832 ◽  
Author(s):  
S. H. Chandler ◽  
L. J. Goldberg
Keyword(s):  
Guinea Pig ◽  
Reticular Formation ◽  
Short Pulse ◽  
Short Latency ◽  
Emg Activity ◽  
Digastric Muscle ◽  
Medullary Reticular Formation ◽  
Jaw Movements ◽  
Stimulus Train ◽  
Stimulation Of

1. In the ketamine-anesthetized guinea pig, electromyographic (EMG) responses of the digastric muscle and vertical and horizontal movements of the mandible were studied when loci within the caudal pontine and rostral medullary reticular formation were stimulated during rhythmic jaw movements (RJMs) evoked by stimulation of the masticatory area of the cortex. 2. Within these regions electrical brain stem stimulation of the pontis nucleus caudalis and nucleus gigantocellularis (PnC-Gi) of the reticular formation completely blocked RJMs at stimulus intensities as low as 10 microA while suppressing the short-latency digastric EMG response that was time locked to each cortical stimulus in the train. PnC-Gi stimulation did not, however, reduce the excitability of the short-latency corticotrigeminal excitatory pathway to digastric motoneurons when tested by short pulse train stimulation at 2 Hz (3 pulses, 500 Hz, 0.3 ms) in the absence of RJMs. 3. Short trains (80 ms) of PnC-Gi stimuli delivered at various phases of the RJM cycle produced a permanent phase shift of the RJM rhythm. If the stimulus train was delivered at an early phase of the cycle (8-40%) the next cycle onset was advanced; if the train was delivered later in the cycle (60-80%) the next cycle onset was delayed. Long trains of PnC-Gi stimuli (100, 200, 300, and 400 ms) increased the time of onset of the next cycle by an amount directly proportional to the duration of the stimulus train. 4. Digastric EMG activity occurring during cortically evoked RJMs occupied nearly 50% of the cycle. If a short train of PnC-Gi stimuli was delivered between approximately 5 and 125 ms after the onset of the burst, the duration of the burst was significantly shortened. 5. These results demonstrate that the suppression of cortically evoked RJMs resulting from PnC-Gi stimulation is due to direct effects on central circuits responsible for the production of the RJM behavior and not on the motoneurons themselves. The evidence presented is consistent with our previously presented hypothesis that the neurons involved in mediating the short-latency corticotrigeminal pathway to digastric motoneurons are separate and distinct from those neurons comprising the central networks responsible for the production of the fundamental jaw oscillation during RJMs.

Myosin Heavy Chain Composition in Human Masticatory Muscles by Immunohistochemistry and Gel Electrophoresis

2003 ◽  
Vol 51 (1) ◽  
pp. 113-119 ◽  
Author(s):  
J.A.M. Korfage ◽  
T.M.G.J. Van Eijden
Keyword(s):  
Myosin Heavy Chain ◽  
Correlation Coefficient ◽  
Heavy Chain ◽  
Fiber Type ◽  
Masticatory Muscles ◽  
Digastric Muscle ◽  
Type I ◽  
Fiber Types ◽  
Hybrid Fibers ◽  
Cross Sectional

In this study we compared the immunohistochemically quantified fiber type area with the myosin heavy chain (MyHC) contents of a bundle of fibers from a human masticatory muscle. The total cross-sectional areas were determined immunohistochemically for the three major fiber types (I, IIA, and IIX) in bundles of fibers ( n = 42) taken from the anterior and posterior belly of the human digastric muscle ( n = 7). The relative MyHC contents of the same fiber bundles were determined electrophoretically (MyHC-I, -IIA, and -IIX; anterior, 32%, 35%, and 33%; posterior, 39%, 42%, and 19%) and compared with the immunohistochemical data (MyHC-I, -IIA, and -IIX; anterior, 32%, 31%, and 37%; posterior, 39%, 45%, and 15%). No significant differences were seen in the mean fiber type distribution between the two techniques; the correlation coefficient ranged from 0.71 to 0.96. The correlation coefficient was higher for MyHC type I and MyHC type IIX than for MyHC type IIA. The MyHC contents of single fibers taken from the posterior belly indicated that many fibers in this belly co-express MyHC-IIA and MyHC-IIX. Despite the presence of these hybrid fibers, the correspondence between both methods was relatively large.

scholarly journals Physical Activity Patterns of Women with a Twin Pregnancy—A Cross-Sectional Study

2021 ◽  
Vol 18 (15) ◽  
pp. 7724
Author(s):  
Katarzyna Kwiatkowska ◽  
Katarzyna Kosińska-Kaczyńska ◽  
Izabela Walasik ◽  
Agnieszka Osińska ◽  
Iwona Szymusik
Keyword(s):  
Physical Activity ◽  
Pregnant Women ◽  
Twin Pregnancy ◽  
Activity Patterns ◽  
Multiple Pregnancy ◽  
Cross Sectional Study ◽  
Sources Of Information ◽  
Sectional Study ◽  
Cross Sectional ◽  
Physically Active

Background: No specific physical activity guidelines are available for women in multiple pregnancy. Aim of the study was to assess the knowledge and experience of women regarding physical activity during their latest twin pregnancy. Methods: A cross-sectional study including women after a twin delivery was conducted in Poland. A questionnaire was distributed in 2018 via web pages and Facebook groups designed for pregnant women. Results: 652 women filled out the questionnaire completely. Only 25% of women performed any physical exercises during twin gestation. The frequency of preterm delivery was similar in physically active and non-active participants. 35% of the respondents claimed to have gained information on proper activity from obstetricians during antenatal counselling while 11% claimed to be unable to identify the reliable sources of information. 7% of women admitted to feel discriminated by social opinion on exercising during a twin pregnancy. Conclusions: The population of women with a twin gestation is not sufficiently physically active and is often discouraged from performing exercises during gestation. Therefore, it is crucial to inform obstetricians to recommend active lifestyle during a twin gestation and to provide reliable information on physical activity to pregnant women. Further research on this topic is necessary in order for obstetric providers to counsel women on appropriate exercise with a twin pregnancy.

086 Sleep midpoint after job loss predicts breakfast skipping patterns

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A36-A36
Author(s):  
Leah Callovini ◽  
Gaby Gubka ◽  
Candace Mayer ◽  
Darlynn Rojo-Wissar ◽  
David Glickenstein ◽  
...  
Keyword(s):  
Job Loss ◽  
Activity Patterns ◽  
Sleep Onset ◽  
Daily Routine ◽  
Cross Sectional ◽  
Circadian Phase ◽  
Breakfast Skipping ◽  
Occupational Transitions ◽  
The Relationship ◽  
Significant Covariates

Abstract Introduction Few studies have examined circadian phase after job loss, an event that upends daily routine. It is common that a daily routine begins with the consumption of breakfast, and breakfast behavior may contribute to health status in adults. Therefore, we sought to examine whether a later midpoint of sleep was associated with breakfast skipping among adults whose schedules were no longer dictated by employment. Methods Data were obtained from the Assessing Daily Activity Patterns Through Occupational Transitions (ADAPT) study. The sample of 155 participants had involuntarily lost their jobs in the last 90 days. Both cross-sectional and 18-month longitudinal analyses assessed the relationship between sleep midpoint after job loss and current and later breakfast skipping. Assessment periods were 14 days. Sleep was measured via actigraphy, and breakfast skipping was measured via daily diary (1 = had breakfast; 0 = did not have breakfast). The midpoint of sleep was calculated as the circular center based on actigraphy sleep onset and offset times. Results The midpoint of sleep at baseline was negatively associated with breakfast consumption at baseline (B = -.09, SE = .02, p = .000). Also, a later midpoint was associated with breakfast skipping over the next 18 months (estimate = -.08; SE = .02; p = .000). Prospective findings remained significant when adjusting for gender, ethnicity, age, perceived stress, body mass index (BMI), education, and reemployment over time. Education (estimate = 14.26, SE = 6.23, p < .05) and BMI (estimate = -.51, SE = .25, p < .05) were the only significant covariates. No other sleep indices predicted breakfast behavior cross-sectionally or prospectively. Conclusion Consistent with research in adolescents, unemployed adults with a later circadian phase are more likely to skip breakfast more often. Breakfast skipping was also associated with higher BMI. Taken together, these findings provide support for the future testing of sleep/wake scheduling interventions to modify breakfast skipping and potentially mitigate weight gain after job loss. Support (if any) #1R01HL117995-01A1

scholarly journals Physiology of a Microgravity Environment Invited Review: Microgravity and skeletal muscle

2000 ◽  
Vol 89 (2) ◽  
pp. 823-839 ◽  
Author(s):  
Robert H. Fitts ◽  
Danny R. Riley ◽  
Jeffrey J. Widrick
Keyword(s):  
Skeletal Muscle ◽  
Muscle Atrophy ◽  
Thin Filament ◽  
Molecular Mechanisms ◽  
Skeletal Muscle Atrophy ◽  
Microgravity Environment ◽  
Type I ◽  
Fiber Types ◽  
Maximal Velocity ◽  
Cross Sectional

Spaceflight (SF) has been shown to cause skeletal muscle atrophy; a loss in force and power; and, in the first few weeks, a preferential atrophy of extensors over flexors. The atrophy primarily results from a reduced protein synthesis that is likely triggered by the removal of the antigravity load. Contractile proteins are lost out of proportion to other cellular proteins, and the actin thin filament is lost disproportionately to the myosin thick filament. The decline in contractile protein explains the decrease in force per cross-sectional area, whereas the thin-filament loss may explain the observed postflight increase in the maximal velocity of shortening in the type I and IIa fiber types. Importantly, the microgravity-induced decline in peak power is partially offset by the increased fiber velocity. Muscle velocity is further increased by the microgravity-induced expression of fast-type myosin isozymes in slow fibers (hybrid I/II fibers) and by the increased expression of fast type II fiber types. SF increases the susceptibility of skeletal muscle to damage, with the actual damage elicited during postflight reloading. Evidence in rats indicates that SF increases fatigability and reduces the capacity for fat oxidation in skeletal muscles. Future studies will be required to establish the cellular and molecular mechanisms of the SF-induced muscle atrophy and functional loss and to develop effective exercise countermeasures.

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