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At least 1,315 records · Page 73Linked to original sources
PubMed1991

The lower trapezius flap. Vascular anatomy and surgical technique.

The lower trapezius flap was first described in 1980 based on the transverse cervical artery. The older anatomical literature, however, describes the dorsal scapular artery as a major contributor of blood supply to the skin overlying the lower trapezius fibers. To clarify this, 30 dissections of this vascular region were performed. In 15 of 30 dissections, the dorsal scapular artery was dominant and the distal transverse cervical artery arose from the dorsal scapular. In nine of 30 dissections, the transverse cervical artery was dominant and the distal dorsal scapular artery arose from the transverse cervical. In six of 30 dissections, both proximal arteries were of equal caliber with no distal communication. We describe a surgical technique that makes use of the lower trapezius flap with inclusion of the dorsal scapular artery; this technique greatly extends the usefulness of the lower trapezius flap, while decreasing the morbidity caused by division of the upper portion of the trapezius muscle during flap harvest.

Arteries↗
PubMed2000

Evolution and development of distinct cell lineages derived from somites.

In the vertebrate embryo, the somites arise from the paraxial mesoderm as paired mesodermal units in a craniocaudal sequence. Segmentation is also the underlying principle of the body plan in annelids and arthropods. Genes controlling segmentation have been identified that are highly conserved in organisms belonging to different phyla. Segmentation facilitates movement and regionalization of the vertebrate body. Its traces in humans are, for example, vertebral bodies, intervertebral disks, ribs, and spinal nerves. Somite research has a history of at least three centuries. Detailed morphological data have accumulated on the development of the avian somite. Especially in connection with the quailchick interspecific marker system, progress was made toward an understanding of underlying mechanisms. At first each somite consists of an outer epithelium and a mesenchymal core. Later, the ventral portion of the somite undergoes de-epithelialization and gives rise to the sclerotome, whereas the dorsal portion forms the dermomyotome. The dermomyotome is the source of myotomal muscle cells and the dermis of the back. It also yields the hypaxial muscle buds at flank level and the myogenic cells invading the limb buds. The dorsal and ventral somitic domains express different sets of developmental control genes, for example, those of the Pax family. During later stages of development, the sclerotomes undergo a new arrangement called "resegmentation" leading to the fusion of the caudal half of one sclerotome with the cranial half of the following sclerotome. Further somitic derivatives include fibroblasts, smooth muscle, and endothelial cells. While sclerotome formation is controlled by the notochord, signals from the dorsal neural tube and ectoderm support the development of the dermomyotome. Myogenic precursor cells for the limb bud are recruited from the dermomyotome by the interaction of c-met with its ligand scatter factor (SF/HGF). In the evolution of metamerism in vertebrates, the first skeletal elements were primitive parts of neural arches, while axial elements developed only later in teleosts as pleurocentra and hypocentra.

Animals↗
PubMed1978

Cyclobenzaprine hydrochloride effect on skeletal muscle spasm in the lumbar region and neck: two double-blind controlled clinical and laboratory studies.

A new drug, Cyclobenzaprine hydrochloride (Flexeril), was compared with diazepam (Valium) and placebo in double-blind trials for efficacy in treating spasms and pain in the neck and low back. Complex recording methods involving clinical evaluations (graded), patient self-ratings, goniometry, motion analysis by computer, electromyography of controlled motions and detailed statistical analysis were used. Clinical improvement over two weeks was statistically significant in all treatment groups with a statistically significant preference for Cyclobenzaprine hydrochloride. The most striking improvements recorded were in the electromyographic findings, which showed statistically significant changes for the Cyclobenzaprine group. Clinical muscle spasms are not accompanied by increased myoelectric activity; the reverse is true. With improvement, myoelectric activity in back muscles is augmented during prescribed stressful movements as measured by electromyography and computer analysis combined with complex electrogoniometry.

Administration, Oral↗
PubMed2001

Cyclobenzaprine and back pain: a meta-analysis.

BACKGROUND: Back pain is a common problem for which cyclobenzaprine hydrochloride is frequently prescribed. OBJECTIVE: To perform a systematic review of cyclobenzaprine's effectiveness in the treatment of back pain. METHODS: We searched MEDLINE, PsycLIT, CINAHL, EMBASE, AIDSLINE, HEALTHSTAR, CANCERLIT, the Cochrane Library, Micromedex, Federal Research in Progress, and the references of reviewed articles, and contacted Merck, Sharpe and Dohme for English-language, randomized, placebo-controlled trials of cyclobenzaprine in adults with back pain. Outcomes included global improvement and 5 specific domains of back pain (local pain, muscle spasm, range of motion, tenderness to palpation, and activities of daily living). Study quality was assessed using the methods of Jadad. Summary outcomes were obtained using a random-effects model. RESULTS: Patients treated with cyclobenzaprine were nearly 5 times (odds ratio, 4.7; 95% confidence interval, 2.7-8.1) as likely to report symptom improvement by day 14 as were those treated with placebo. Slightly fewer than 3 individuals (2.7; 95% confidence interval, 2.0-4.2) needed treatment for 1 to improve. The magnitude of this improvement was modest, with an effect size of 0.38 to 0.58 in all 5 outcomes (local pain, muscle spasm, tenderness to palpation, range of motion, and activities of daily living). Treatment efficacy for these 5 outcomes was greatest early, in the first few days of treatment, declining after the first week. Patients receiving cyclobenzaprine also experienced more adverse effects, the most common being drowsiness. CONCLUSIONS: Cyclobenzaprine is more effective than placebo in the management of back pain; the effect is modest and comes at the price of greater adverse effects. The effect is greatest in the first 4 days of treatment, suggesting that shorter courses may be better. Studies comparing the relative value of acetaminophen, nonsteroidal anti-inflammatory drugs, and cyclobenzaprine individually and in combination in the treatment of back pain are needed.

Amitriptyline↗
PubMed1984

Ontogeny of avian extrinsic ocular muscles. I. A light- and electron-microscopic study.

Light- and electron-microscopic studies were performed on those tissues that are supposed to deliver the anlagen of the extrinsic ocular muscles. Since the blastemata of the ocular muscles can be traced back into the prechordal mesoderm, it can be concluded that this tissue is the source of these muscles. In embryos from stage 8-10 according to Hamburger and Hamilton (HH) cells are found to detach from the lateral border of the prechordal mesoderm. These cells are assumed to give rise to the trochlearis and abducens musculature. In stage-14 embryos the paired premandibular cavity arises within the lateral wings of the prechordal mesenchyme. In 4-day embryos the lateral wall of each premandibular cavity becomes denser forming a premuscular mass, which is subdivided into the anlagen of the oculomotorius muscles in 5-day embryos. The head cavities are not homologous to somites because their structures, origins and sites are very different.

Animals↗
PubMed2002

Effects of GnRH analogues, 'add-back' steroid therapy, antiestrogen and antiprogestins on leiomyoma and myometrial smooth muscle cell growth and transforming growth factor-beta expression.

The objective of this study was to elucidate the biological significance of GnRH and antiprogestins and antiestrogen in leiomyoma and their interactions with ovarian steroid 'add-back' therapy. Leiomyoma and myometrial smooth muscle cells (LSMC and MSMC) were isolated and exposed to GnRH agonist (leuprolide acetate, LA), 17beta-estradiol (E2), medroxyprogesterone acetate (MPA), GnRH antagonist (Antide), estrogen antagonist, ICI182780 (Fulvestrant) and progesterone antagonists RU486 (Mifepristone) and ZK98299 (Onapristone) and combinations thereof. The rate of DNA synthesis, cell proliferation and transforming growth factor-beta (TGF-beta) expression were then determined. In both cell types, we found that in a dose-dependent manner, LA inhibited, whereas E2, MPA and the combination of E2 + MPA stimulated, the rate of DNA synthesis in these cells. Antide reversed the inhibitory effect of LA, while LA partly inhibited the stimulatory effect of the steroids. In addition, RU486, ICI182780 and ZK98299 at 0.1 micro mol/l or higher doses inhibited the rate of DNA synthesis and partly reversed the effects of E2 and/or MPA. We also found that LSMC expressed elevated levels of TGF-beta1 compared with MSMC. In both cell types, the effects of LA, E2, MPA, RU, ZK and ICI and combinations thereof on TGF-beta1 production were reflective of their effects on DNA synthesis. In line with this, TGF-beta1 was found to stimulate DNA synthesis and the E2-, TGF-beta1- or E2 + TGF-beta1-induced DNA synthesis was found to be inhibited by TGF-beta1 neutralizing antibodies and/or LA. In conclusion, the results provide further evidence that GnRH agonist- and RU486-induced leiomyoma regression is mediated in part through an interactive mechanism that results in altered cell growth and suppression of TGF-beta production.

Estradiol↗
PubMed1993

Electromyographic power spectrum analysis of the paraspinal muscles. Long-term reliability.

As a prerequisite to the use of electromyographic power spectral analysis of the paraspinal muscles as a low-back pain treatment outcome measure, the long-term reliability of the technique was assessed. The myoelectric signals of the multifidus and iliocostalis lumborum muscles of healthy sedentary women were analyzed with regard to spectral parameters during a constant-force contraction, before and after a 3-month period. Results indicated that for both muscles, estimates of initial median frequency and amplitude had high test/retest reliability, but that the recovery and left-right difference parameters were not stable. Using a confidence interval method, test/retest variation for the fatigue parameter was found to be within the range of variability of potentially underlying metabolic processes.

Adult↗
PubMedDate not supplied

[Blood gas analysis of forearm veins--at rest and after exercise of forearm muscles and laser Doppler flowmetry of skin on the back of the palm--use in evaluation of microcirculation in diabetes type 2].

The aim of the study was to compare of nondominant forearm microcirculation in adult-type diabetes and healthy subjects with use of venous blood gasometry (vbg) sampled from basilic vein before and after exercise of antebrachial muscles and with use of laser doppler fluxometry (LDF) with optode localized in dorsal palm surface. Examinations were performed in groups of 16 diabetic patients (aged 43.5 +/- 5.7) and 16 healthy subjects (aged 39.3 +/- 7.8). After exercise of antebrachial muscles in diabetic patients in vbg were: pH higher, pO2 and satO2 lower than in healthy subjects, pCO2 and -HCO3 were not different in both group. In LDF in diabetic patients impaired hypraemic reaction, impaired heating to 40 degrees C reaction and hyperaemic reaction in this temperature were found.

Adult↗
PubMed2002

Can increased intra-abdominal pressure in humans be decoupled from trunk muscle co-contraction during steady state isometric exertions?

The purpose of the present study was to investigate whether increased intra-abdominal pressure (IAP) can be achieved without elevating the overall trunk muscle co-contraction that causes increased spine compression force. Ten subjects performed isometric trunk flexion, extension, and lateral bending exertions while generating 0%, 40% and 80% of their maximal IAP or while co-contracting trunk muscles without consciously raising IAP. An additional three subjects performed a variety of ramp IAP, co-contraction and isometric exertion tasks while holding their breaths and while exhaling. An 18 degree-of-freedom, electromyogram (EMG)-assisted biomechanical model was used to quantify trunk muscle co-contraction with calculations of spine compression force and stability. Spine stability and compression force increased proportionally with increased IAP regardless of whether the subjects intentionally generated IAP or consciously avoided it. This increase was accomplished with significantly greater co-contraction of 12 major trunk muscles. The EMG activation of all muscles was highly correlated with IAP and intra-thoracic pressure (ITP) ( r from 0.59 to 0.95). Activity of the thoracic erector spinae correlated the best with ITP ( r=0.81), which in turn was correlated with IAP ( r=0.91). It was not possible to co-contract trunk muscles without generating IAP and ITP, or conversely to generate IAP without trunk muscle co-contraction and increased ITP.

Abdominal Cavity↗
PubMed1987

The activity of individual trunk muscles during heavy physical loading.

The myoelectric activity of ten trunk muscles were recorded, using intramuscular electrodes, when ten subjects made maximal and 50% of maximal static exertions in standing postures. Exertions were made in flexion, extension, and left and right lateral bending. Three heavy-lifting tasks also were studied. A biomechanical model was used to predict the forces in the trunk muscles, and the predictions then were compared to the measurements. The abdominal muscles were all active in attempted flexion, while the erector spinae muscles were inactive. In attempted extension, the erectors were maximally active, but considerable activity was present in the abdominal muscles as well. The highest activity levels recorded in the oblique abdominal muscles were in lateral bending. There were high degrees of correlation between the measured muscle activities and predicted muscle tensions for the erector spinae and rectus abdominus muscles, while the correlation coefficients for the oblique abdominal muscles were lower (0.4-0.7). The study indicates that inclusion of antagonistic activity is an important consideration to improve model predictions. The oblique abdominal muscles appear to be more active, in general, than predicted. For the longitudinal trunk muscles, the predictions are excellent throughout.

Abdominal Muscles↗
PubMed1989

Exploration of mechanical and electromyographic responses of trunk muscles to high-intensity resistive exercise.

The purposes of this study were to determine the effects of high intensity exercise on fatigue of the trunk muscles within a test session, and on multiple kinetic and electromyographic (EMG) variables over a 6-week training period. Fourty-five normal men and women (20-40 years of age) completed the study. The KIN/COM trunk testing unit (Chattecx Corporation, Chattanooga, Tennessee) was used for both testing and training. The results of the study follow: 1) The KIN/COM trunk testing system was very accurate, and the method used was highly reproducible for the kinetic variables. Reproducibility for the endurance variables was mixed, and isolated EMG variables were poor. 2) Kinetic and EMG decrements associated with fatigue did occur in the trunk muscles with ten continuous cycles of maximal concentric and eccentric contractions. 3) Trunk muscle strength gains were highest for the same mode of exercise used in training (specificity), but significant strength gains also were seen in different modes of muscle contraction (transfer of training). For the trunk extensors, the eccentric form of exercise was superior. 4) The rate of isometric torque development and decay was increased by exercise in men. 5) Trunk muscle endurance was retained when gains in strength occurred. 6) The majority of variables reflecting strength and endurance were retained. The methods and results can serve as guidelines for the evaluation of trunk muscle function and resistive exercise in the clinic.

Abdominal Muscles↗
PubMed1992

The influence of lordosis on axial trunk torque and trunk muscle myoelectric activity.

Force contributions from the facet complex and posterior ligaments during the generation of axial torque are a function of lordosis, and it has been speculated that these forces together with muscular contributions play a role in axial trunk twisting. This study investigated the electromyographic activity of the trunk musculature and torque-generating capacity of the lumbar spine under the conditions of normal lordosis, hyperlordosis, and hypolordosis. Eleven male subjects volunteered for this study. The subjects performed isometric twisting efforts and maximum dynamic twisting efforts at 30 degrees/sec. The myoelectric activity levels (normalized to maximal amplitude obtained from nontwist activities) were quite low despite maximal efforts to generate axial torque (for example: approximately 60% maximum voluntary contraction for latissimus dorsi and even lower for the abdominals). Furthermore, changes in lordosis did not produce any consistent changes in muscle activity, although a hyperlordotic spine produced significantly smaller axial torques, and a hypolordotic spine smaller still. Larger torques were measured during all three conditions of lordosis, as the subjects rotated toward an untwisted position, and lower torques as the subjects rotated away. The opposite trend was observed, however, in myoelectric activity of the agonistic side of latissimus dorsi, the thoracic level of erector spine, and the lumbar level of erector spinae, i.e., larger amplitudes were observed as the trunk was twisted away from the untwisted position. These data suggest that tissues other than muscle (i.e., passive tissue) contribute significantly to axial torque production and that the flexed and twisted spine is less able to resist applied axial torques, possibly increasing the risk of torsional injury.

Abdominal Muscles↗
PubMed2002

An ergonomic comparison between mechanical and manual patient transfer techniques.

Multiple studies have concluded that manual patient transfer and repositioning techniques are a significant cause of low back injuries. The objective of this study was to compare the low back stresses resulting from the use of two different mechanical patient transfer assist devices with the use of traditional manual transfer techniques. The mechanical transfer systems used were the Barton Patient Transfer System and a Sling-Suspension Lift similar to a "Hoyer Lift". The back compressive forces derived using the Michigan 3D Static Strength Model (Version 4.0) and electromyography (EMG) of the muscles of the low back were compared. This study found that the mechanical assist devices placed less stress on the low back and were more desirable to use than the traditional manual techniques. The Barton System was found to be, in general, less hazardous and more preferred than the Sling Suspension Lift.

Adult↗