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At least 487 records · Page 27Linked to original sources

PubMed1979

Role of the somitic mesoderm in the development of the thorax in bird embryos. II. Origin of thoracic and appendicular musculature.

The regional embryonic origin of trunk and limb musculature was determined through heterospecific homotopic or heterotopic transplantations of quail somitic or somiticsomatopleural mesoderm into chick hosts, and through localized X-irradiation of the somitic mesoderm. Experiments were performed on 2-day embryos. Results show that the myoblastic component of all truncal and appendicular muscles is of somitic origin. Intra- and perimuscular connective tissue as well as tendons are of somatopleural origin. X-ray destruction of the somitic mesoderm at and beyond the wing level resulted in the complete or almost complete absence of musculature in the wing and corresponding truncal region. The mapping of the cephalocaudal origin of the various muscles was found to be as follows: Intrinsic and extrinsic muscles of the wing and scapular girdle Somites 12-20 Grand pectoral muscle Somites 12-22 Intercostal muscles Somites 19-26 Abdominal muscles Somites 27-29 Intrinsic and extrinsic muscles of the leg and pelvic girdle Somites 26-32 Dorsal and intervertebral muscles Metameric level, specific origin In the heterotopic transplantations, the grafted somitic mesoderm gave rise to site-specific morphogenesis, irrespective of the cephalocaudal level of its origin. This result demonstrates that, at 2 days of incubation, the myogenic somitic cells are not regionalized.

Animals↗

PubMed1987

Medullary expiratory activity: influence of intercostal tendon organs and muscle spindle endings.

Studies were conducted to determine the effects of intercostal muscle spindle endings (MSEs) and tendon organs (TOs) on medullary expiratory activity in decerebrate cats. Impeded intercostal muscle contractions, elicited by electrical stimulation of the peripheral cut end of the T6 ventral root, were used to stimulate intercostal TOs without MSEs. Impeded contractions of the intercostal muscles augmented expiratory laryngeal motoneuron activity, and either had no effect on or reduced the activity of bulbospinal expiratory neurons. Vibration was used to stimulate intercostal MSEs. Intercostal MSEs had no effect on medullary expiratory neuron activity. It is concluded that both external and internal intercostal TOs have an excitatory effect on expiratory laryngeal motoneuron activity and an inhibitory effect on a subpopulation of expiratory neurons driving intercostal and/or abdominal muscles, and intercostal MSEs have no direct influence on medullary expiratory activity.

Animals↗

PubMed1999

Spatial distribution of external and internal intercostal activity in dogs.

1. The observation that the external and internal interosseous intercostal muscles in the dog show marked regional differences in mechanical advantage has prompted us to re-examine the topographic distribution of electrical activity among these muscles during spontaneous breathing. 2. Inspiratory activity was recorded only from the areas of the external intercostals with an inspiratory mechanical advantage, and expiratory activity was recorded only from the areas of the internal intercostals with an expiratory mechanical advantage. The expiratory discharges previously recorded from the caudal external intercostals and the inspiratory discharges recorded from the rostral internal intercostals were probably due to cross-contamination. 3. Activity in each muscle area was also quantified relative to the activity measured during tetanic, supramaximal nerve stimulation (maximal activity). External intercostal inspiratory activity was consistently greater in the areas with a greater inspiratory advantage (i.e. the dorsal aspect of the rostral segments) than in the areas with a smaller inspiratory advantage, and internal intercostal expiratory activity was invariably greatest in the areas with the greatest expiratory advantage (i.e. the dorsal aspect of the caudal segments). 4. This topographic distribution of neural drive confers to the external intercostal muscles an inspiratory action on the lung during breathing and to the internal interosseous intercostals an expiratory action.

Animals↗

PubMed1997

[Respiration mechanics in tetraplegia].

Patients with quadriplegia due to transection of the lower cervical cord show, on spirographic examination, a marked decrease in vital capacity and its two components, i.e. inspiratory capacity (i.c.) and expiratory reserve volume (ERV). The loss of IC results partly from the decreased inspiratory muscle strength consecutive to the intercostal muscle paralysis but mostly from a reduction in the distensibility of the lungs and the rib cage. The reduction in ERV is related to the paralysis of all the well-recognized muscles of expiration (abdominals, interosseous internal intercostals); however, the clavicular portion of the pectoralis major allows these patients to maintain a small ERV.

Elasticity↗

PubMed1994

[Body surface dynamic monitoring of respiratory muscles in patients with cor pulmonale].

Electromyography (EMG) of diaphragm (Edi) and intercostal muscle (Ein) in 30 healthy volunteers and 28 patients with cor pulmonale or pulmonary fibrosis were analysed. The results show that (1) there is no obvious activity of Ein to be observed and the frequency spectra are stable when the healthy volunteers breath quietly, (2) the activity of Ein and the amplitude of Edi increase when patients are in compensation stage, (3) the patients with serious respiratory failure, the amplitude of Edi decreases remarkably, (4) the frequency spectras of Edi appear wave-like changes with the breathing pattern of patients.

Adult↗

PubMed1998

Activity of respiratory pump and upper airway muscles during sleep onset.

Ventilation decreases at sleep onset. This change is initiated abruptly at alpha-theta electroencephalographic transitions. The aim of this study was to determine the contributions of reduced activity in respiratory pump muscles and upper airway dilator muscles to this change. Surface electromyograms over the diaphragm (Di) and intercostal muscles and fine-wire intramuscular electrodes in genioglossus (GG) and tensor palatini (TP) muscles were recorded in nine healthy young men. It was shown that phasic Di and both phasic and tonic TP activities were lower during theta than during alpha activity. Breath-by-breath analysis of the changes at alpha-theta transitions during the sleep-onset period showed a number of changes. At alpha-theta transitions, phasic activity of Di, intercostal, and GG muscles fell and rose again, and phasic and tonic activities of TP fell and remained at low levels during theta. With a state transition from theta to alpha, the phasic and tonic activities of the Di, GG, and TP increased dramatically. It is now clear that the fall in ventilation that occurs with sleep is related to a fall in activities of both upper airway dilator muscles and respiratory pump muscles.

Adolescent↗

PubMedDate not supplied

Age changes of motor innervation and acetylcholine receptor distribution on human skeletal muscle fibres.

Age changes of motor innervation and acetylcholine receptor (AChR) distribution on human intercostal muscle fibres (age 32-76 years) were investigated by using combined silver and acetylcholinesterase (AChE) staining method and [125I]alpha-bungarotoxin autoradiography. In the older subjects, (1) the number of preterminal axons entering an endplate and the length of endplate increased, and (2) the endplate was composed of a greater number of smaller conglomerates of AChRs, as compared with the younger subjects. In addition, (3) perijunctional AChRs were observed in the older subjects, but not in the younger ones. Linear relationships were observed between each of these parameters and age. These results suggest that there are gradual changes in the pre- and postsynaptic components of human skeletal muscle endplate over adult life.

Adult↗

PubMed1993

Regional distribution of myosin heavy chain isoforms in rib cage muscles as a function of postnatal development.

We studied the expression of myosin heavy chain (MHC) isoforms, utilizing electrophoretic methods, in rib cage (RC) muscles: the scalenus medius, the parasternal, cephalic, midthoracic, and caudal intercostal muscles; and in the diaphragm (DI) of rats during postnatal development and when mature. At day 1, all RC muscles and the DI expressed MHC neonatal/embryonic (69-92% of total MHC complement) with little MHC slow and 2A; the RC muscles alone expressed a small proportion of MHC 2B (2-4%). On day 4, MHC neonatal/embryonic expression still predominated (55-71%) but increased MHC 2A expression was observed in both the RC (11-21%) and DI (31%); MHC 2B (5-7%) was noted in the RC muscles but not the DI. By day 14, MHC neonatal/embryonic and 2A expression each comprised a third of the total MHC complement of the RC muscles, MHC 2X was first observed, and MHC 2B expression increased. The day 14 DI was comprised of equal proportions of MHC neonatal/embryonic, slow and 2A with little MHC 2X (11%). The adult and day 30 animals expressed comparable muscle-specific MHC phenotypes: the DI characterized by a proportional mixture of MHC slow, MHC 2A, and MHC 2X, with little MHC 2B, whereas the RC muscles expressed predominantly MHC 2B (40-62%). We conclude that the RC muscles and DI show comparable MHC phenotypes in the immediate newborn period but differ in their MHC expression during postnatal development and when mature. The RC muscles show only minor intermuscle variations in MHC phenotype during development, and when mature are characterized by fast MHC isoform expression, particularly MHC 2B.

Aging↗

PubMed1978

On the transmission of the stimulating effects of carbon dioxide to the muscles of respiration.

1. Electromyography was used to measure the response of the diaphragm and intercostal muscles to CO2 in artificially ventilated decerebrate cats. 2. Hypocapnia produced tonic activity in either inspiratory or expiratory muscles or both, according to the preparation. 3. A graded effect of CO2 on both rhythmic and tonic activity was observed and for the latter this could be seen at as low as 10 torr PA,CO2. 4. In one human subject tonic firing of expiratory motoneurones was also induced by hypocapnia and this activity showed a graded increase with increasing (CO2. 5. A saggital incision of the medulla aimed at interrupting inspiratory bulbospinal axons abolished activity in inspiratory muscles and at eupnoeic levels of CO2 converted the activity of expiratory muscles from a periodic to a topic firing pattern. 6. Following such lesions the threshold for rhythmic excitation of expiratory muscles was elevated and this revealed that the graded effect of CO2 on tonic expiratory activity extends to as high as 60 torr. 7. The tonic activation of respiratory muscles in response to CO2 ceased after cervical cord transection or when the saggital incision in the medulla was extended caudally to the first cervical segment. 8. It is concluded that the CO2 dependent activation of spinal respiratory motoneurones is conveyed by bulbospinal axons which decussate in the vicinity of the obex and that this activation can be rhythmic or tonic. 9. It is suggested that the rhythmic excitation of expiratory muscles derives from a periodic inhibition of expiratory bulbospinal neurones which are subjected to a tonic CO2 dependent excitation which is continuously variable over the physiological range.

Action Potentials↗

PubMed1998

Segmental distribution of the motoneurons innervating trunk muscles in the spinal cord of the cat and rat.

The current progress in developmental biology suggests a genetically stable peripheral pathway formation. However, this may be incompatible with the variations or anomalies observed in the segmental origins of motor nerves in the mammals including the human. For the consideration of the causes raising this inconsistency, we examined the distribution of motoneurons for the serratus dorsalis cranialis muscle of the cat using a retrograde labeling method because this muscle consists of segmentally-arranged parts which receive segmental dual innervation. Consequently, the distribution of the labeled motoneurons for one part spread throughout the full extent of two spinal cord segments, while the distributions for the intercostal muscles in the cat and rat were segmental and in accordance with each spinal cord segment. This may indicate the more precise correspondence between the spinal nerve segments and the distribution of motoneurons projecting axons through them. We think, therefore, that segments of the spinal nerves supplying a given target exactly indicate the segmental levels of supplying motoneurons and suggest the segments of somites from which primordial cells of the target migrate.

Animals↗

PubMed1988

Responses in human intercostal and truncal muscles to motor cortical and spinal stimulation.

Percutaneous electrical stimulation of the human motor cortex (up to 750 V) has been used to study the cortical projections to intercostal and truncal muscles. The latencies of electromyographic (EMG) responses were measured to motor cortical stimuli and also to spinal stimulation of the appropriate nerve roots. Following single anodal stimuli at (or near) the vertex, short-latency responses were recorded in pectoralis major (mean 9.6 msec), latissimus dorsi (9.7 msec), paravertebral muscles (11.1 msec), 3rd/4th parasternal intercostals (11.1 msec), and 6th/7th intercostal muscles (12.3 msec). Responses in each muscle group were potentiated by background voluntary respiratory and truncal manoeuvres which activated the muscles. The mean estimated central conduction times from motor cortex to spinal segmental level were 4.8 msec for pectoralis major, 5.8 msec for parasternal intercostals and 6.2 msec for 6th/7th intercostal muscles. The central conduction times and properties of the cortically evoked responses are consistent with a rapidly conducting, oligosynaptic pathway from the human motor cortex to accessory respiratory muscles and to truncal muscles.

Adult↗

PubMed1998

Cortical excitability of the biceps muscle after intercostal-to-musculocutaneous nerve transfer.

OBJECTIVE: Restoration of volitional control over elbow flexion has been demonstrated in patients who have undergone intercostal-to-musculocutaneous nerve transfer. We investigated the cortical area involved in the control over elbow flexion after intercostal-to-musculocutaneous nerve transfer. METHODS: Maps of magnetically excitable cortical areas of the affected arms of five patients were compared with maps of their healthy arms and maps of both arms of four healthy control subjects. The intercostal cortical area was also studied, requiring needle electromyography mapping (n = 1). RESULTS: The cortical areas of affected arms were smaller and less excitable than those of healthy arms. The locations of these areas could not be distinguished from that of the normal cortical biceps area but seemed to differ from that of the intercostal cortical area. CONCLUSION: The existence of a biceps-like cortical area related to the reinnervated muscle can be explained in two ways. Interneurons from the original biceps area might excite the cortical neurons controlling the intercostal muscles. Alternatively, corticospinal neurons of the original biceps area may project directly onto spinal intercostal motor neurons. Cerebral plasticity does occur in intercostal-to-musculocutaneous nerve transfers and may be crucial for their clinical success.

Adolescent↗

PubMedDate not supplied

Extra peritoneal transposition of spleen in portal hypertension--a new operative technique.

The author describes a procedure for portal circulation bypass in the treatment of esophageal varices. The systemic circulation is shunted with the spleen, which is transposed extraperitoneally and thus will have a raw area on its convex surface, to adhere to the exposed muscle of the diaphragm, inner intercostal muscles of the posterior abdominal wall. The portal blood is thus partly directed to the inferior phrenic vein and the intercostal veins and ultimately drains into the azygous systems. With this procedure the ascites fluid seeps out of the peritoneal cavity along the edges of the spleen and therefore has a larger absorption surface in the extraperitoneal space, apart from the improved suprahepatic portal drainage provided.

Child↗

PubMed1981

Decay of inspiratory muscle activity and breath timing in man.

Time required by moving average EMG of diaphragm and parasternal intercostal muscle to decay to 25% of its peak (T0.25) decreased of expiratory time (TE). Accordingly, relative decay rate (RDRI) of EMG increased of breathing frequency (f). This confirms conclusions based on decay of inspiratory muscle pressure under discontinuous inspiratory elastic load (DIL). Data were better fitted by power functions: only this combination of T0.25 vs. TE and RDRI vs. f equations provided a relationship fitting corresponding inspiratory time vs. TE data. For each timing, RDRI of EMG was higher under DIL than during unloaded breathing. Under DIL scattering of EMG data increased, coupling between diaphragm and parasternal muscle EMG decreased, and RDRI of EMG was higher than that of pressure, likely because of muscle intrinsic properties. This difference decreased with the increase of f: this could be due to recruitment of fast fibers at high f. Both during loaded and unloaded breathing T0.25 was proportional to time from peak to zero EMG, indicating that decay shape did not change with timing.

Action Potentials↗

PubMed1997

Role of joint receptors in modulation of inspiratory intercostal activity by rib motion in dogs.

1. Inspiratory activity in the canine external intercostal muscles is exquisitely sensitive to the direction and amplitude of the inspiratory displacement of the ribs. This study was designed to investigate the role of muscle receptors, in particular the muscle spindles, in mediating this phenomenon. 2. External intercostal inspiratory activity showed a reflex increase when the normal cranial motion of the ribs and the normal shortening of the muscles was reduced, and showed a reflex decrease when the cranial motion of the ribs and the shortening of the muscles was augmented. However, clamping the two ribs making up the interspace and maintaining muscle length constant only moderately attenuated these responses. 3. These persistent responses remained unchanged after section of the levator costae muscles. 4. The responses were attenuated but still present after section of the external intercostals in the contiguous segments and denervation of the internal intercostals. 5. These reflex responses are therefore mediated in part by non-muscular receptors, which most likely lie within the costovertebral joints. These joint receptors might be a primary determinant of the load-compensating reflex.

Animals↗

PubMedDate not supplied

The individuality of chest wall motion in tetraplegia.

We have studied the motion of the chest wall in eight supine tetraplegic subjects using optical contour mapping. Measurements were obtained during quiet breathing, exaggerated breathing, during the course of a deep inspiration and during static inspiratory efforts. The pattern of motion showed a high degree of individual variability which did not appear to be related to the age of the patient, the duration of injury or the presence of intercostal muscle spasticity. By contrast, it did appear to be related to the presence of bony rib cage stiffness, and possibly the action of the neck accessory muscles. The pattern of rib cage motion in tetraplegia is more complex than conventionally thought.

Abdominal Muscles↗

PubMed1991

Chloride channel regulation in the skeletal muscle of normal and myotonic goats.

External intercostal muscle biopsies from normal and congenitally myotonic goats were studied in vitro at 30 degrees C using a two-microelectrode square-pulse cable analysis assisted by computer. The resting chloride conductance (Gcl) was estimated from the difference between the mean membrane conductance in chloride-containing and chloride-free bathing media. The protein kinase C (PKC) activator, 4-beta-phorbol-12,13-dibutyrate. (0.1-2.0 microM) blocks a maximum of 76% of Gcl in normal goat fibers and induces myotonic hyperexcitability similar to that of congenitally myotonic goat fibers. The Gcl block was partially antagonized by pretreatment with the PKC inhibitor, staurosporine (10 microM). The "inactive" 4-alpha-phorbol-12,13-didecanoate had no effect at 50 microM, whereas the "active" 4-beta isomer blocked 41% Gcl at 1 microM. The nearly absent Gcl of congenitally myotonic goat fibers was not restored by treatment with high concentrations of the PKC inhibitors staurosporine, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H7), or tetrahydropapaveralone (THP). Also, forskolin and cholera toxin, which may increase cyclic adenosine monophosphate (cAMP) levels, or the R(+) clofibric acid enantiomers and taurine, which increase Gcl in normal fibers, were also unable to restore Gcl in myotonic goat fibers. The data suggest that PKC may be a chloride channel regulator in normal goat skeletal muscle fibers, however the molecular defect of congenitally myotonic fiber does not appear to be due to excessive activity of PKC.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1996

Chest wall muscle cross talk in canine costal diaphragm electromyogram.

The present paper describes the influence of cross talk from the abdominal and intercostal muscles on the canine diaphragm electromyogram (EMG). The diaphragm EMG was recorded with bipolar surface electrodes placed on the costal portion of the diaphragm (abdominal side), aligned in the fiber direction, and positioned in a region with a relatively low density of motor end plates. The results indicated that cross talk may occur in the diaphragm EMG, especially during conditions of loaded breathing and light general anesthesia. The cross-talk signals showed characteristics that were entirely different from the diaphragm EMG. Although the diaphragm EMG was typical for signals recorded with electrodes aligned in the fiber direction, the cross-talk signals were characteristic of those obtained with electrode pairs not aligned in the direction of the muscle fibers. Alterations in electrode positioning, interelectrode distance, and/or electrode surface area cannot guarantee the elimination of cross-talk signals, whereas spinal anesthesia at a high thoracic level will paralyze the sources of the cross talk and hence eliminate the cross-talk signals. By taking advantage of the differences in EMG signal characteristics for the diaphragm EMG and cross-talk signals, an index that has the capability to detect cross talk was developed.

Abdominal Muscles↗