RESUMEN
The accuracy with which the fibre direction of the multifidus muscle can be predicted in females is comparable to that for males, and is well within the limits of accuracy obtainable in the placement of surface electrodes in relation to a reference line drawn on the skin, i.e. +/- 5 degrees. In females, the observed deviation of the iliocostalis fibres from the corresponding reference line may, however, add some degree of error to the proper orientation of electrode bars perpendicular to muscle fibres. It may thus be concluded that the surface recording of EMG power spectrum parameters of the iliocostalis in women cannot be carried out as accurately as for the multifidus muscle. Nevertheless, the resulting recording error associated with a possible orientation deviation of, for example, 13 degrees is rather small (3%) and may be acceptable for clinical research purposes.
Asunto(s)
Músculos/anatomía & histología , Caracteres Sexuales , Anciano , Electromiografía/métodos , Femenino , HumanosRESUMEN
Some parameters of the electromyographic power spectrum of the paraspinal muscles were recorded and analyzed with regard to their ability to discriminate between normal controls and patients with back pain classified as "avoiders" or "confronters" by their responses to the Pain Behavior Checklist. In terms of the activity of the multifidus muscle, the avoider group displayed spectral changes towards lower frequencies, reduced variability in the density spectrum, and higher values of estimated initial frequencies. Measures of the activity of the iliocostalis lumborum did not contribute in any significant way to these group differences. Based on these findings, and on the available literature concerning the histology and physiology of paraspinal muscles, it is proposed that the observed characteristics of the avoider group may be due to a reduced ratio of slow twitch to fast twitch muscle fibers in the multifidus.
Asunto(s)
Dolor de Espalda/diagnóstico , Electromiografía , Enfermedad Crónica , Análisis Discriminante , Femenino , Humanos , Región Lumbosacra , Masculino , Valores de ReferenciaRESUMEN
The present study examined the relative accuracy and precision of MR and CT procedures for determining the CSA of individual muscles from the human thigh. Serial AN, CT and MR cross-sections were obtained from three cadaveric lower limbs. The MR measurements provided accurate and precise values for the CSAs of most thigh muscles, generally within +/- 7.5% of the AN standard. In contrast, CT tended systematically to overestimate the AN CSA by 10-20%. Retest procedures indicated that highly reliable measurements could be obtained from both MR and CT images. However, subjective interpretations of boundaries between closely apposed muscle bellies, particularly for muscles with more than one head, were necessary for resolving entities in the imaging records and this decreased the relative accuracy of MR and CT measures. Interestingly, MR records demonstrated an incomplete septum between vastus lateralis and vastus intermedius more prominently than AN cross-sections. The novel cross-validation procedures used in this study also highlighted several system-based errors in the MR records that, if undetected and left uncorrected, would have seriously biased the morphometric data obtained with this technique. In general, MR provides high resolution images of the human thigh muscles which may be used to obtain valid measures of the CSA of these structures.
Asunto(s)
Imagen por Resonancia Magnética , Músculos/anatomía & histología , Muslo/anatomía & histología , Tomografía Computarizada por Rayos X , Cadáver , Humanos , Masculino , Músculos/diagnóstico por imagen , Muslo/diagnóstico por imagenRESUMEN
The dynamic pattern of scapulohumeral rhythm and the scapular instantaneous center of rotation were studied in 20 healthy young male subjects. The most common pattern of scapulohumeral rhythm was characterized by three separate phases, with the greatest relative amount of scapular rotation occurring between 80 and 140 degrees of arm abduction. The scapular instantaneous center of rotation was observed to be located initially at, or near, the medial root of the scapular spine, and gradually migrated toward the region of the acromioclavicular joint as arm abduction progressed. A biomechanical model of the shoulder girdle was proposed by correlating the results from the present study with the electrical activity of the scapular rotators. This model is useful in demonstrating the true dynamic function of the muscles acting on the scapula as well as the mechanical efficiency of upward scapular rotation during arm abduction.
Asunto(s)
Brazo/fisiología , Movimiento , Escápula/fisiología , Adulto , Fenómenos Biomecánicos , Humanos , Masculino , Músculos/fisiología , RotaciónRESUMEN
In 20 healthy, young adult male subjects, the muscular activity of the upper, middle and lower trapezius and the lower digitations of the serratus anterior were studied electromyographically during arm abduction in the plane of the scapula. The patterns of electrical activity of the trapezius and lower serratus anterior muscles were observed to increase progressively during abduction of the arm; however, a plateau phase was demonstrated in all four of the muscle parts studied. Despite the presence of considerable individual variability, common trends were observed in muscular activity patterns. It is believed that the patterns of muscle activity may be closely related to mechanical factors such as scapulohumeral rhythm and a migrating scapular Instantaneous Centre of Rotation (ICR) during arm elevation.
Asunto(s)
Brazo/fisiología , Músculos/fisiología , Escápula/fisiología , Adolescente , Adulto , Electrodos , Electromiografía/métodos , Humanos , Masculino , Movimiento , Valores de ReferenciaRESUMEN
Observations were made from the dissection of 156 digital joints (thumbs excluded). In all joints fibrocollagenous menisci projected into the articular cavity from a ring-like structure based on the joint capsule. These meniscal structures separated the articulating cartilage surfaces at the margins of the joint. Histological examination confirmed a fibrocartilaginous nature of the tissue which demonstrated positive staining for proteoglycans and collagen fibers. Although generally similar in form, these meniscal structures varied in extent when compared between joint groups. The greatest amount and articular contribution was noted in metacarpophalangeal joints with least being found distally.
Asunto(s)
Articulaciones de los Dedos/anatomía & histología , Mano/anatomía & histología , Anciano , Cartílago Articular/patología , Colágeno/análisis , Histocitoquímica , Humanos , Persona de Mediana EdadRESUMEN
Brain sectioning has been improved through gelatin embedding so that more than forty precisely oriented serial sections can be obtained from a single brain. Since the embedding gelatin requires no fixation, it can be removed from the sections prior to staining by simple warming. The reduction of Berlin blue dye commonly observed after staining by the Mulligan method has been found to be at least partly due to light in the UV to near UV range. Dye reduction is significantly inhibited by postfixation in 25% acetic acid.