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At least 1,477 records · Page 82Linked to original sources
PubMed2001

Intramuscular myoelectric activity and selective coactivation of trunk muscles during lateral flexion with and without load.

STUDY DESIGN: Myoelectric activity of trunk muscles was measured intramuscularly in six healthy subjects as they maintained static trunk postures at 0 degrees, 15 degrees, and 30 degrees of lateral bending, unloaded or holding a 20-kg load in one hand alongside the body. OBJECTIVE: To determine the position and load dependency of the agonistic and antagonistic myoelectric responses of deep and superficial trunk lateral flexor muscles. SUMMARY OF BACKGROUND DATA: Loading of the trunk in lateral bending is associated with incidences of low back pain. The neuromotor control of muscles surrounding the spine may be decisive for its vulnerability. Earlier documentation of the activation pattern of trunk muscles, particularly those situated deeply, is incomplete. METHODS: Trunk angle was measured between S1-C7 and the vertical with a protractor. Electromyographic activity was recorded unilaterally from eight trunk muscles using intramuscular fine-wire electrodes inserted under the guidance of ultrasound. RESULTS: The electromyographic data showed that all muscles on the side contralateral to the load, except rectus abdominis, had their highest activity while loaded in the position most laterally flexed to the loaded side. The degree of bilateral coactivation was greater for the ventral than for the dorsal muscles. CONCLUSIONS: The myoelectric responses of most lumbar trunk muscles to static lateral flexion were dependent on trunk position and loading. The abdominal muscles demonstrated more coactivation than the other trunk muscles, and thus appeared to contribute more to trunk stabilization in laterally bent and loaded trunk positions.

Abdomen↗
PubMed1993

Magnetic resonance imaging findings of lumbar spine in the young: correlation with leisure time physical activity, spinal mobility, and trunk muscle strength in 15-year-old pupils with or without low-back pain.

From a population of 1,503 schoolchildren, 38 15-year-old children reporting recurrent or continuous low-back pain and 38 asymptomatic controls (34 boys and 42 girls) matched for age, sex, and school class were selected for tests of spinal mobility and trunk muscle strength, and for a magnetic resonance imaging (MRI) study of the lumbar spine. In addition, the subjects were asked about leisure time physical activities in an interview preceding the measurements. Spinal muscular atrophy was the only finding that was more common among physically inactive subjects (p = 0.005). Moreover, increased occurrence of disk degeneration (DD) was observed in the low-activity group. However, the difference was not significant. Neither Scheuermann-type changes nor DD were related to spinal mobility or trunk muscle strength. Children with disk protrusion were, on the average, taller (p = 0.044), and their lumbar flexion measured by flexicurve was decreased (p = 0.043). Our results strengthen further the evidence that MRI is a sensitive measure and that imaging findings must be interpreted carefully with respect to pain and physical impairment of the lumbar spine. Furthermore, no clear evidence of the association between physical activity and early DD could be found.

Abdominal Muscles↗
PubMed1998

Classification of paraspinal muscle impairments by surface electromyography.

The purpose of this article is to provide an overview of research to develop surface electromyographic (EMG) measurements for classification of paraspinal muscle impairments in persons with low back pain (LBP). The process of developing laboratory and clinically based protocols is described. Results of studies to evaluate the reliability of these measurements and their relationships with impairments and function are discussed. Research efforts to incorporate EMG spectral measurements, such as the median frequency, into a classification system to identify different types of muscle impairments are documented. Discriminant functions have been calculated based on case-control studies to identify 2 kinds of LBP impairments from constant-force isometric tasks: (1) excessive fatigue due to muscle deconditioning and (2) inhibition of muscle activation secondary to pain or pain-related behaviors. New areas of investigation designed to improve the classification accuracy of such functions using procedures other than discriminant analysis are described. Work in progress to extend the application of the technique to tasks other than those involving just isometric contraction, including those involving repetitive trunk movement, is also described.

Adult↗
PubMed2000

Monosynaptic projections from the nucleus retroambiguus to motoneurons supplying the abdominal wall, axial, hindlimb, and pelvic floor muscles in the female rhesus monkey.

The nucleus retroambiguus (NRA) consists of premotor neurons in the caudal medulla. It is involved in expiration, vomiting, vocalization, and probably reproductive behavior by means of projections to distinct motoneuronal cell groups. Because no information is available about the NRA and its efferent pathways in primates, the present study examines NRA projections to the lumbosacral spinal cord in female rhesus monkeys. To identify the NRA, wheat germ agglutinin-horseradish peroxidase (WGA-HRP) was injected into the lumbosacral cord in three monkeys. To study the distribution of NRA axons in the lumbosacral cord, WGA-HRP injections were made into the NRA in seven monkeys. To identify motoneuronal cell groups receiving input from the NRA, the same seven monkeys also received cholera toxin subunit b (CTb) injections into different hindlimb, axial, and pelvic floor muscles. The results show that NRA neurons projecting to the lumbosacral cord are mainly located between 1 to 4 mm caudal to the obex. They send numerous axons to external oblique and pelvic floor motoneurons, whereas projections to iliopsoas and axial motoneurons are less numerous. The projections are bilateral, but show a clear contralateral predominance in the iliopsoas, axial, and pelvic floor motoneuronal cell groups. At the ultrastructural level, NRA-terminal profiles make asymmetrical contacts with labeled and unlabeled dendrites in these motoneuronal cell groups and contain large amounts of spherical and a few dense core vesicles. It is concluded that the NRA is well developed in the monkey and that there exists a direct pathway from the NRA to lumbosacral motoneurons in this species. The finding that the NRA projects to a somewhat different set of motoneuronal cell groups compared with other species fits the concept that it is not only involved in expiration-related activities but also in species specific receptive and submissive behavior.

Abdominal Muscles↗
PubMed1976

[Meat quality of broiler rabbits. 2. Chemical composition of meat of valuable cut-up parts of New Zealand white rabbits and hybrids of different body weight].

Studies were carried out on the chemical composition of the meat of valuable cut-up parts in 88 broiler rabbits (51 New Zealand White, 37 hybrids). Muscles of legs and backs differed in nutrient content. The fat content of legs was higher than that of M.long.dorsi, and directly related to increasing carcass weights. As to the varieties mostly insignificant effects on chemical constituents were measured. There were but a few correlations between the analysed qualitative properties.

Animals↗
PubMed2003

Somatosensory areas engaged during discrimination of steady pressure, spring strength, and kinesthesia.

The aim of this study was to locate neuronal populations in the somatosensory areas engaged during discrimination of differences in: (1) static sustained pressure on the distal phalanx (PRESS); (2) spring strengths (SSTIFF) during active flexion of the right index finger; and (3) the change in position of a limb with contracting muscles, i.e., kinesthesia (KIN), during active flexion of the right index finger. The stimuli used were spring-loaded cylinders. The regional cerebral blood flow (rCBF) was measured with positron emission tomography (PET). The active fields were related to cytoarchitectonic areas of the somatosensory cortex (areas 3a, 3b, 1, and 2) and the primary motor cortex (areas 4a and 4p). We hypothesized that SSTIFF and KIN would activate areas 3a and 2. All three conditions, when contrasted against a rest condition, activated cytoarchitectural areas 3b, 1, and 2, and presumptive somatosensory areas in the left parietal operculum and right supramarginal gyrus in accordance with these areas receiving information from cutaneous mechanoreceptive afferents. Area 3a was only activated in SSTIFF and KIN, consistent with observations in monkeys and cats, showing that afferents from muscle receptors project to area 3a, and indicating that a similar arrangement seems to be apparent in humans. SSTIFF and KIN activated the right anterior lobe of the cerebellum, the left area 4a and left area 2 more than did PRESS, likely due to a combination of active movements and muscle receptor feed-back.

Adult↗
PubMed2006

Laminin peptide-conjugated chitosan membrane: Application for keratinocyte delivery in wounded skin.

Tissue engineering requires the delivery and survival of cells to organ sites needing repair. Previously, we showed that an active laminin peptide (AG73: RKR-LQVQLSIRT)-conjugated chitosan membrane promoted cell adhesion and spreading in vitro. Here, we seeded human keratinocytes onto AG73-chitosan membranes and found that nearly 80% of the cells were attached to the membranes within 2 h. The membranes carrying the keratinocytes were inverted and placed onto exposed muscle fascia on the backs of nude mice. After 3 days, the keratinocytes had migrated from the membrane and established a stratified epidermis-like structure on the fascia. Cells recognize the AG73 through transmembrane proteoglycan syndecans, which recognition system has not previously been tested in tissue engineering applications. We suggest that the AG73-chitosan membrane is useful as a therapeutic formulation and is applicable as a cell delivery system such as delivering keratinocytes to a wound bed.

Animals↗
PubMedDate not supplied

Metabolic compartmentation and substrate channelling in muscle cells. Role of coupled creatine kinases in in vivo regulation of cellular respiration--a synthesis.

The published experimental data and existing concepts of cellular regulation of respiration are analyzed. Conventional, simplified considerations of regulatory mechanism by cytoplasmic ADP according to Michaelis-Menten kinetics or by derived parameters such as phosphate potential etc. do not explain relationships between oxygen consumption, workload and metabolic state of the cell. On the other hand, there are abundant data in literature showing microheterogeneity of cytoplasmic space in muscle cells, in particular with respect to ATP (and ADP) due to the structural organization of cell interior, existence of multienzyme complexes and structured water phase. Also very recent experimental data show that the intracellular diffusion of ADP is retarded in cardiomyocytes because of very low permeability of the mitochondrial outer membrane for adenine nucleotides in vivo. Most probably, permeability of the outer mitochondrial membrane porin channels is controlled in the cells in vivo by some intracellular factors which may be connected to cytoskeleton and lost during mitochondrial isolation. All these numerous data show convincingly that cellular metabolism cannot be understood if cell interior is considered as homogenous solution, and it is necessary to use the theories of organized metabolic systems and substrate-product channelling in multienzyme systems to understand metabolic regulation of respiration. One of these systems is the creatine kinase system, which channels high energy phosphates from mitochondria to sites of energy utilization. It is proposed that in muscle cells feed-back signal between contraction and mitochondrial respiration may be conducted by metabolic wave (propagation of oscillations of local concentration of ADP and creatine) through cytoplasmic equilibrium creatine and adenylate kinases and is amplified by coupled creatine kinase reaction in mitochondria. Mitochondrial creatine kinase has experimentally been shown to be a powerful amplifier of regulatory action of weak ADP fluxes due to its coupling to adenine nucleotide translocase. This phenomenon is also carefully analyzed.

Adenosine Diphosphate↗
PubMed1996

Anatomic basis of the lower trapezius musculocutaneous flap.

Differences in the description of the blood supply of the lower trapezius m. and the fact that all former findings are based on very few cases caused us to reinvestigate the arterial supply of the lower trapezius m. Based on the anatomic investigation of 70 human cadavers, the trapezial branch of the dorsal scapular a. was found to be the constant vessel to the lower trapezius m. The origin of the dorsal scapular a., however, was found to be very variable. In 45% it was a direct branch of either the subclavian a. or the costocervical trunk. In the remaining 55% the dorsal scapular a. formed different trunks with the superficial cervical a. and/or suprascapular a. branching off either the subclavian a., the thyrocervical trunk, or the internal thoracic a. Additional segmental musculocutaneous perforators also supply the lower part of the trapezius m. and the overlying skin. Consequently, the lower or ascending part of the trapezius m. has a vascular pattern type V. Thus, the lower trapezius musculocutaneous flap merits consideration in head and neck reconstruction.

Back↗
PubMed2003

[Drug therapy of back pain].

The importance of analgesic drugs in the treatment of low back pain is a matter of intense debate. Based on the current literature, a multidisciplinary approach combining drug treatment with physical and psychotherapy has proven to be the most successful treatment of back pain. This perspective is challenged by various anesthesiologists who claim that early use of opioids in back pain therapy is the concept of choice. The results of recent studies regarding this matter are controversial. This chapter reviews the historical background of analgetic drugs and provides an overview of the current diagnostic and therapeutic options in the treatment of back pain. Recommendations are given based on the results of current randomized controlled studies.

Analgesics↗
PubMed2006

Soft tissue determinants of low back pain.

Low back pain is one of the complaints most commonly seen in the clinical setting. Correctly or incorrectly, these patients are often given the diagnosis of fibromyalgia, myofascial pain syndrome, disk herniation, or some other label. It is important to recognize the soft tissue causes of low back pain and understand how they can be most appropriately diagnosed and managed. Nonligamentous disorders of the low back region may occur in isolation or in combination with underlying discogenic, ligamentous, and facet-mediated causes of pain. Therefore, in order to fully evaluate and treat a patient with low back pain, it is necessary to consider and address these soft tissue conditions. This paper reviews soft tissue causes of low back pain and discusses how they are most appropriately diagnosed and managed.

Fascia↗
PubMed1978

Modification of Marshall-Marchetti-Krantz operation.

In a classic article published in 1949 Marshall, Marchetti, and Krantz demonstrated that stress incontinence in women without uterine prolapse could be corrected by a simple vesicourethral suspension. Beginning in 1960 one of the authors (W.E.C.) became concerned about suturing the urethra to the periosteum of the pubis. It occurred to him that use of the upper sutures only to pull up the bladder and hold its anterior wall to the back of the rectus muscles might be just as effective, and this has proved to be so.

Adult↗
PubMedDate not supplied

Low back pain.

Explore the source record for details and available documents.

Amitriptyline↗
PubMed2007

Spine stability: the six blind men and the elephant.

Stability is one of the most fundamental concepts to characterize and evaluate any system. This term is often ambiguously used in spinal biomechanics. Confusion arises when the static analyses of stability are used to study dynamic systems such as the spine. Therefore, the purpose of this paper is to establish a common ground of understanding, using standard, well-defined terms to frame future discussions regarding spine dynamics, stability, and injury. A qualitative definition of stability, applicable to dynamic systems, is presented. Additional terms, such as robustness (which is often confused with stability) and performance are also defined. The importance of feedback control in maintaining stability is discussed. Finally, these concepts are applied to understand low back pain and risk of injury.

Biomechanical Phenomena↗
PubMed2004

Electromyographic activity of voluntarily activated trunk flexor and extensor muscles in post-stroke hemiparetic subjects.

OBJECTIVE: To study the EMG activity of selected trunk muscles during self-initiated voluntary flexion and extension of the trunk in post-stroke hemiparetic subjects, and to compare measurement results to corresponding findings in control subjects. METHODS: Using a sample of 50 patients and 30 control subjects, bilateral EMG activity of the rectus abdominis (RA) and external oblique (EO) muscles was studied during direct trunk flexion, and activity of the lumbar erector spinae (ES) and latissimus dorsi (LD) was studied during straight trunk extension. Variables of timing, magnitude, and temporal synchronization between muscle activity on the paretic and non-paretic sides of the body in the patient group were compared with the same measurements taken from the left and right sides of the body in the control group. RESULTS: Activity of the RA and LD muscles on the affected side of the body was reduced and delayed relative to the unaffected side in the patients and relative to the control subjects. Some deterioration was also observed in the function of the EO muscle, whereas the lumbar ES displayed normal activity on both sides of the body. Trunk velocity during both flexion and extension was slower in the patients than in the controls. CONCLUSIONS: Despite the existence of ipsilateral as well as contralateral higher inputs to axial and to a lesser extent also to more lateral trunk muscles, the function of the superficial abdominal muscles and of the LD muscle is adversely affected by a contralateral stroke. Conversely, the lumbar ES, which can be categorized as local trunk extensors, seem to normally fulfill their anti-gravitational task on both sides of the body.

Abdominal Muscles↗