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PubMed1993

Corticocortical connections of area F3 (SMA-proper) and area F6 (pre-SMA) in the macaque monkey.

The monkey mesial area 6 comprises two distinct cytoarchitectonic areas: F3 [supplementary motor area properly defined (SMA-proper)], located caudally, and F6 (pre-SMA), located rostrally. The aim of the present study was to describe the corticocortical connections of these two areas. To this purpose restricted injections of neuronal tracers (wheat germ-agglutinin conjugated to horseradish peroxidase, fluorescent tracers) were made in different somatotopic fields of F3, F6, and F1 (area 4) and their transport plotted. The results showed that F3 and F6 differ markedly in their cortical connections. F3 is richly linked with F1 and the posterior premotor and cingulate areas (F2, F4, 24d). Connections with the anterior premotor and cingulate areas (F6, F7, F5, 24c) although present, are relatively modest. There is no input from the prefrontal lobe. F3 is also connected with several postrolandic cortical areas. These connections are with areas PC, PE, and PEa in the superior parietal lobule, cingulate areas 23 and PEci, the opercular parietal areas (PFop, PGop, SII) and the granular insula. F6 receives a rich input from the anterior premotor areas (especially F5) and cingulate area 24c, whereas its input from the posterior premotor and cingulate areas is very weak. A strong input originates from area 46. There are no connections with F1. The connections with the postrolandic areas are extremely meagre. They are with areas PG and PFG in the inferior parietal lobule, the disgranular insula, and the superior temporal sulcus. A further result was the demonstration of a differential connectivity pattern of the cingulate areas 24d and 24c. Area 24d is strongly linked with F1 and F3, whereas area 24c is connected mostly with F6. The present data support the notion that the classical SMA comprises two functionally distinct areas. They suggest that F6 (the rostral area) is responsible for the "SMA" so-called high level motor functions, whereas F3 (the caudal area) is more closely related to movement execution.

Animals↗
PubMed2004

Functional connectivity as revealed by spatial independent component analysis of fMRI measurements during rest.

Cortical functional connectivity, as indicated by the concurrent spontaneous activity of spatially segregated regions, is being studied increasingly because it may determine the reaction of the brain to external stimuli and task requirements and it is reportedly altered in many neurological and psychiatric disorders. In functional magnetic resonance imaging (fMRI), such functional connectivity is investigated commonly by correlating the time course of a chosen "seed voxel" with the remaining voxel time courses in a voxel-by-voxel manner. This approach is biased by the actual choice of the seed voxel, however, because it only shows functional connectivity for the chosen brain region while ignoring other potentially interesting patterns of coactivation. We used spatial independent component analysis (sICA) to assess cortical functional connectivity maps from resting state data. SICA does not depend on any chosen temporal profile of local brain activity. We hypothesized that sICA would be able to find functionally connected brain regions within sensory and motor regions in the absence of task-related brain activity. We also investigated functional connectivity patterns of several parietal regions including the superior parietal cortex and the posterior cingulate gyrus. The components of interest were selected in an automated fashion using predefined anatomical volumes of interest. SICA yielded connectivity maps of bilateral auditory, motor and visual cortices. Moreover, it showed that prefrontal and parietal areas are also functionally connected within and between hemispheres during the resting state. These connectivity maps showed an extremely high degree of consistency in spatial, temporal, and frequency parameters within and between subjects. These results are discussed in the context of the recent debate on the functional relevance of fluctuations of neural activity in the resting state.

Adult↗
PubMed1988

Regeneration studies on a crayfish neuromuscular system. I. Connectivity changes after intersegmental nerve transplants.

The superficial flexor muscles of the crayfish are a neuromuscular system of a few muscle cells innervated by six neurons in a precise position-dependent pattern. The neurons are capable of regenerating their normal connectivity patterns within a short span of time when conditions are favorable. The superficial flexor muscles of the second and third segments, despite their similarities in neuronal and muscle cell size and number, have distinctive connectivity patterns; some homologous neurons form similar patterns but other homologous neurons form patterns that are reversed between segments. We transplanted each segment's nerve into each other's muscle in order to observe regeneration of the nerves into a target area that differed in connectivity patterns from their original muscle. During the first weeks of regeneration all neurons formed a connectivity pattern with more connections medially and declining connections laterally, a pattern determined by the medial location of the nerve transplant. This pattern is maintained for most of the neurons, but for some there is an eventual reduction in medial connections as maximum synapse formation shifts to the lateral muscle fibers. Three of the eight neurons studied were able to regenerate connectivity patterns that corresponded to their segment of origin and not to their host muscle. This suggests that intersegmental muscle differences are not influencing the formation of these connectivity patterns, so the neurons will follow their inherent synaptogenesis program.

Animals↗
PubMed1994

Echocardiographic evaluation of hearts with twisted atrioventricular connections (criss-cross heart).

An echocardiographic study was performed on seven patients with twisted atrioventricular connections (criss-cross heart) relative to the usual atrial arrangement. The atrioventricular connections were concordant in five patients and discordant in two. The ventriculoarterial junction was either double-outlet right ventricle (n = 6) or discordant connections (n = 1). Associated cardiac defects were ventricular septal defect (n = 7), pulmonary stenosis (n = 5), straddling tricuspid valve (n = 2), and straddling mitral valve (n = 1). Malalignment between the atrial and ventricular septum was the most important feature of this disease and resulted in altered spatial orientation of the trabecular ventricular septum, and recesses in the ventricles and the right atrium. When assessed by echocardiography, these anatomical features were not invariably recognized in every case, but they were dependent upon the type of atrioventricular connections and the presence of straddling of the atrioventricular valves. Left ventricular recess was the most consistent feature and was present in every patient, regardless of the atrioventricular connections. Right atrial recess was found in four of five patients with concordant atrioventricular connections but was not present in patients with discordant atrioventricular connections. Right ventricular recess was recognized as such in a single patient with concordant atrioventricular connection and straddling mitral valve. The trabecular septum was oriented in a horizontal plane in hearts with concordant atrioventricular connections and without atrioventricular valve straddling. The trabecular septum was oriented semivertically in all other hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Child, Preschool↗
PubMed2004

An explanation of contextual modulation by short-range isotropic connections and orientation map geometry in the primary visual cortex.

Recent experimental studies on the primary visual cortex have revealed complicated nonclassical neuronal activities. Contextual modulation on orientation-contrast is one typical example of nonclassical neuronal behavior. This modulation by surrounding stimuli in a nonclassical receptive field is mainly thought to be mediated by short- and long-range horizontal connections within the primary visual cortex. Short-range connections are circularly symmetrical and relatively independent of orientation preferences, while long-range connections are patchy, asymmetrical, and orientation specific. Although this modulation can be explained by long-range specific connections qualitatively, recent studies suggest that long-range connections alone may be insufficient with respect to the balance between two types of connections. Here, in order to clarify the role of short-range connections in the process of contextual modulation, we propose a model of the primary visual cortex with isotropic short-range connections and a geometric orientation map. Computational simulations using the model have demonstrated that contextual modulation can be explained by short-range connections alone. This is due to the interaction between the spatial periodicity of orientation domains and the excitatory-inhibitory regions arising from the propagation of activities.

Action Potentials↗
PubMed1999

Connectivity in the somatosensory cortex of the adolescent rat: an in vitro biocytin study.

A promising way to elucidate neuronal information processing is to establish detailed structure-function relationships of identified single neurons or populations of nerve cells, especially their synaptic connectivity. This has been greatly improved by the development of acute brain slice preparations. The cellular physiology of the rodent primary somatosensory (barrel) cortex has been extensively studied. However, for a meaningful interpretation of physiological experiments the degree and pattern of connectivity has to be known for the particular preparation. Since such studies are not available for rat (P15-25) barrel cortex in vitro, we have traced the cortico-cortical and thalamo-cortical connections in 400-microm-thick slices with biocytin. In coronal slices, a wealth of axonal connections in retrograde and anterograde directions were heavily labeled, resembling the full pattern of cortico-cortical projections described in vivo. The most striking connections were vertical and horizontal connections within the primary somatosensory cortex, as well as a columnar projection to the secondary somatosensory cortex and beyond (mainly the parietal ventral area). Electron microscopic extensions of the study indicated that the full possible set of synaptic contacts with an adult-like appearance was already established in these connections. In thalamo-cortical slices, strong reciprocal connections with the ventrobasal (and to a much lesser extent also the posterior) thalamic nucleus were always observed, together with an intensive ramification of fibers in the reticular nucleus. A striatal terminal field was also consistently found. We conclude that all major intracortical and thalamo-cortical connection are richly preserved in the in vitro slice preparations of rats. Thus, these preparations are suitable for elucidation of the functional interaction of the most crucial brain structures involved in somatosensory information processing combining an in vivo-like anatomical structure with the controlled environment of an in vitro slice.

Animals↗
PubMed2004

Predicting anti-HIV activity of 2,3-diaryl-1,3-thiazolidin-4-ones: computational approach using reformed eccentric connectivity index.

The eccentric connectivity index, which has recently been employed successfully for the development of numerous mathematical models for the prediction of biological activities of diverse nature, has been reformed to overcome its limitations caused by degeneracy and insensitivity towards heteroatoms. The reformed eccentric connectivity index, termed the eccentric connectivity topochemical index, overcomes the limitations of the eccentric connectivity index by exhibiting very low degeneracy and displaying sensitivity to both the presence and relative position of heteroatoms without compromizing the discriminating power of the eccentric connectivity index. The relationship of the eccentric connectivity topochemical index, eccentric connectivity index and Wiener's index with regard to the anti-HIV activity of 2, 3-diaryl-1, 3-thiazolidin-4-one derivatives was subsequently investigated. The values of the eccentric connectivity topochemical index, the eccentric connectivity index and Wiener's index of each of 31 analogues comprizing the data set were computed using in-house computer program. Resultant data was analyzed and suitable models developed after identification of active ranges. Subsequently, each derivative was assigned a biological activity using these models, which was then compared with the reported anti-HIV activity. The accuracy of prediction using these models was found to vary from 81 to 90%. The proposed index offers a vast potential for virtual screening of combinatorial libraries, structure property/activity studies and drug design. [figure]. Basic structure of 2,3-diaryl-1, 3-thiazoidin-4-ones.

Anti-HIV Agents↗
PubMed1980

Crossed atrioventricular connections.

Four cases of crossed atrioventricular connections are described. All of them were diagnosed at cardiac catheterization by angiocardiography and one was examined pathologically. Two possessed situs solitus, one with concordant connections and the other with discordant connections; the other had two situs inversus, both of them with concordant connections. Two had double-outlet right ventricle, one had transposition of the great arteries, and the other had normally related and connected great arteries. These cases have been interpreted as representing abnormal rotation of the ventricles following sepatation. A review of 36 cases previously reported on and our own cases, suggests that most patients have concordant atrioventricular connections. There are many types of ventriculo-arterial connections, the most frequent being transposition of the great arteries. There has not been any case reported with persistent truncus arteriosus. On the basis of atrioventriculo-arterial connections, we propose a classification for this malformation. We discuss the importance of the bulboventricular loop in the type of atrioventricular connections, some clinical implications for the diagnosis, and analyze the value of the rules to localize the ventricles by means of the position of the great arteries.

Adolescent↗
PubMed1991

Indications for modification of coexisting dual atrioventricular node pathways in patients undergoing surgical ablation of accessory atrioventricular connections.

Concomitant susceptibility to atrioventricular (AV) node reentrant tachycardia has been demonstrated in certain patients having reentrant tachycardia utilizing accessory AV connections. For those patients undergoing accessory connection ablation, AV node surgical modification may be warranted during the same operative procedure. To assess indications for a combined operative procedure, this study evaluated potential predictors of subsequent spontaneous AV node reentrant tachycardia in patients undergoing ablation of accessory AV connections. Among 62 consecutive patients undergoing surgical ablation of an accessory AV connection, 13 (21%) manifested dual AV node pathways. The latter were identified preoperatively in five patients (four with concealed and one with bidirectional accessory connections) and postoperatively in seven (all seven with bidirectional accessory connections). In one patient with a bidirectional accessory connection, dual AV node pathways could not be demonstrated preoperatively, but AV node reentrant tachycardia was induced. Operative ablation of an accessory connection was successful in all patients. However, postoperatively, 2 of the 13 patients had inducible AV node reentrant tachycardia, 5 had AV node "echo" beats and 6 had no inducible arrhythmia. During 26 +/- 7 months of follow-up study, the two patients with inducible AV node reentrant tachycardia postoperatively had symptomatic AV node reentrant tachycardia. In addition, the one patient with inducible AV node reentrant tachycardia preoperatively had recurrence of this tachycardia 4 months after attempted surgical modification of the AV node. Consequently, although dual AV node pathways appear to be common in patients undergoing surgical ablation of an accessory AV connection (21%), only a small group (3 of 13) of these patients are at risk for subsequent clinical AV node reentrant tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed2004

The effect of sensorimotor activation on functional connectivity mapping with MRI.

The correlations in the fluctuations in the blood oxygenation level-dependent (BOLD) MRI signal between anatomically distinct regions of the cortex that are known components of functional systems have been previously studied as possible indicators of functional connectivity. The objective of this study was to examine the effect of sensorimotor brain activity, as assessed by task-based functional magnetic resonance imaging (fMRI), on functional connectivity indices in the same region. Regions of activation for sequential finger motion were determined using a task-based, block-design fMRI study. Functional connectivity measurements based on interregional correlations were acquired at rest and during continuous, sequential finger motion. Connectivity indices were determined using normalized mean correlations within and between three regions of interest activated for the finger motion task. Connectivity indices were also determined for a control region that was not activated for the task. Continuous motor tasks performed during BOLD measurements did not significantly affect the functional connectivity as compared to the connectivity at rest within or between regions known to be activated by the task. However, there appeared to be a trend suggesting a slight reduction in connectivity indices during the motor task. The connectivity within and between those areas not activated for the task remained unchanged between conditions. These results suggest that in the motor system investigated, the recruitment of neurons to perform a specific task may moderately reduce the degree of hemodynamic coupling within and between regions.

Adult↗
PubMed2006

Dynamic sculpting of brain functional connectivity and mental rotation aptitude.

Changes in long-range synchronization are considered a key mechanism for the integration and segregation of cortical regions mediating cognitive processes. Such synchronization or functional connectivity is reflected in human electroencephalographic (EEG) coherence and in steady-state visually evoked potential (SSVEP) coherence. In this chapter, the relationship between cognitive proficiency in the mental rotation task (MRT) and functional connectivity reflected in SSVEP event-related partial coherence is described. The capacity to estimate changing levels of functional connectivity with a relatively high temporal resolution makes it possible to examine the relationship between functional connectivity at various points in time and aptitude. In the current study, the relationships between functional connectivity and two mental rotation aptitude measures, mental rotation speed and mental rotation accuracy, are described. We observed that functional connectivity was correlated with proficiency and that this correlation was both positive and negative for various regions and points in time. It is suggested that cognitive aptitude is related to the brain's capacity to enhance functional connectivity or communication between cortical regions that are relevant to the cognitive demands while attenuating irrelevant communication. This capacity is termed functional connectivity sculpting, and it is proposed that functional connectivity sculpting may constitute an important functional component of the neural substrate of learning and aptitude.

Brain↗
PubMed1998

The number connection tests A and B: interindividual variability and use for the assessment of early hepatic encephalopathy.

BACKGROUND/AIMS: The number connection tests A and B are regarded as sensitive psychometric measures for the assessment of early hepatic encephalopathy. Review of the studies dealing with the diagnostic sensitivity of the number connection tests, however, shows that the scoring of the number connection tests results differs between studies. Most groups define the limits of the normal range by studying small control groups. Others use scores given in the literature without ensuring the comparability of the test versions used. Thus, there is a need for normative data for the number connection test results and for re-evaluation of the sensitivity of the tests using valid scores. METHODS: In this study the number connection tests A and B were administered to 249 healthy volunteers (age: 18 to 76 years) to analyze the influence of age, education and occupation on their results. In addition, the age-corrected normative data were applied to 169 patients with grade 0-I hepatic encephalopathy. The specificity and sensitivity of age-corrected and age-independent normative data of the number connection tests were compared. RESULTS: There was a significant influence of age and education on the number connection test results, but only a negligible effect of occupation. Application of the age-corrected normative data to the test results of the patients with grade I hepatic encephalopathy significantly decreased the sensitivity of the number connection tests for hepatic encephalopathy compared to widely used age-independent normal ranges, but also increased the specificity. CONCLUSION: The use of standardized versions of the number connection tests and age-related normative data is recommended.

Acute Disease↗
PubMed2003

Identifying confounds to increase specificity during a "no task condition". Evidence for hippocampal connectivity using fMRI.

Functional MRI can be applied to study connectivity in the brain during a "no task condition." This study focuses on applying a multiple linear regression analysis to identify spurious connectivity caused by confounding factors such as physiologic noise and to separate these from hippocampal connectivity caused by the blood oxygen level dependent (BOLD) signal during a no-task condition. Regressors of interest (hippocampal time courses) as well as regressors of no interest (respiratory signal and cerebrospinal fluid), were included in the analysis, and each yielded a connectivity map. This method was applied at high sampling rate (limited volume, proper physiologic noise sampling), low sampling rate (whole brain scans possible), and at high and low spatial resolution in five healthy control subjects. Regressors of no interest showed specific connectivity patterns, different from hippocampal regressors. The latter showed connectivity between left and right hippocampus. The current study shows successful application of a multiple regression analysis to study connectivity between left and right hippocampus. Both maps of hippocampal connectivity caused by BOLD signal and connectivity caused by spurious signals could be identified.

Adult↗
PubMed2004

What was the impact of the introduction of extracardiac completion for a single center performing total cavopulmonary connections?

BACKGROUND: Creation of an extracardiac cavopulmonary connection has been proposed as a superior alternative to the lateral intracardiac tunnel for the completion of total cavopulmonary connection. METHODS AND RESULTS: We made a retrospective review of our experience with 125 patients undergoing a total cavopulmonary connection between June 1994 and January 2003. Our experience with the extracardiac connection for completion began in 1999. Since 1994, we have constructed an intracardiac tunnel in 50 patients, and an extracardiac connection in 75. Of the total number, 83 had undergone an earlier partial cavopulmonary connection. Additional intracardiac procedures were performed in 43 patients at time of completion, in 25 of those undergoing extracardiac completion, and in 18 of the patients having an intracardiac procedure. The mean size of the tube used for completion was 19 mm. The mean cross-clamp time for placement of the intracardiac tunnel was 77 min, with a median of 80.5 min, and a mean cardiopulmonary bypass time of 139 min, with a median of 131 min. For construction of the extracardiac connection, a mean cross-clamp time in 24 of the 75 patients was 54 min, with a median of 54 min. Mean cardiopulmonary bypass time for all the patients with an extracardiac connection was 100 min, with a median of 88 min. Reoperations were needed in 10 patients, 6 having intracardiac and 4 extracardiac procedures. Of these, 5 were early and 5 late, including one take down. None of the patients died after these interventions. Taken overall, 8 patients died, with 5 early deaths. In the multivariable analysis, cardiopulmonary bypass time of more than 120 min, atrioventricular valvar replacement, and banding of the pulmonary trunk prior to the total cavopulmonary connection, all reached statistical significance for early death, whereas only heterotaxy syndrome remained as the sole risk factor for late death. There was no significant difference in survival between the modifications used. DISCUSSION: Whereas we could not identify any clinical superiority for the extracardiac approach in the short-term, the concept of extracardiac completion has helped to simplify the overall procedure. Longer follow-up will be required to elucidate any potential advantages.

Blood Flow Velocity↗
PubMed2005

Fine-scale specificity of cortical networks depends on inhibitory cell type and connectivity.

Excitatory cortical neurons form fine-scale networks of precisely interconnected neurons. Here we tested whether inhibitory cortical neurons in rat visual cortex might also be connected with fine-scale specificity. Using paired intracellular recordings and cross-correlation analyses of photostimulation-evoked synaptic currents, we found that fast-spiking interneurons preferentially connected to neighboring pyramids that provided them with reciprocal excitation. Furthermore, they shared common fine-scale excitatory input with neighboring pyramidal neurons only when the two cells were reciprocally connected, and not when there was no connection or a one-way, inhibitory-to-excitatory connection. Adapting inhibitory neurons shared little or no common input with neighboring pyramids, regardless of their direct connectivity. We conclude that inhibitory connections and also excitatory connections to inhibitory neurons can both be precise on a fine scale. Furthermore, fine-scale specificity depends on the type of inhibitory neuron and on direct connectivity between neighboring pyramidal-inhibitory neuron pairs.

Action Potentials↗
PubMed2003

Location of accessory connection in infants presenting with supraventricular tachycardia in utero: clinical correlations.

The most common mechanism of fetal tachycardia is orthodromic reciprocating tachycardia utilizing an accessory atrioventricular connection, however, data regarding accessory connection location in patients with fetal tachycardia is limited. To investigate the location of accessory connections in fetal tachycardia, postnatal transesophageal electrophysiology studies were performed at one institution over a 10-year period in 24 infants with documented fetal tachycardia. The 18 infants with inducible orthodromic reciprocating tachycardia were grouped according to accessory connection location, and groups were compared regarding prenatal presentation and clinical course. Left-sided connections were found in 13 (72%) patients, while accessory connection location could not be determined in the remaining 5 (28%) patients. The presence of a left-sided accessory connection was associated with sustained tachycardia, depressed ventricular function, and the need for antiarrhythmic therapy in utero. No other difference in clinical or electrophysiologic data was found between groups. Our findings indicate that a high proportion of patients with fetal tachycardia have left-sided accessory connections, and a left-sided connection may adversely affect fetal hemodynamics and cardiac output.

Bundle-Branch Block↗
PubMed2000

Suppression of the secretion of atrial and brain natriuretic peptide after total cavopulmonary connection.

OBJECTIVES: Among the modifications of the Fontan operation currently being used, total cavopulmonary connection offers the greatest potential for optimizing early and long-term postoperative outcomes. Although studies have established that abrupt increases in right atrial pressure elevate the plasma atrial natriuretic peptide level after the Fontan procedure, changes in plasma natriuretic peptide levels after total cavopulmonary connection have not been clarified. Our hypothesis is that secretion of atrial natriuretic peptide may be suppressed in patients undergoing total cavopulmonary connection because the atrium continues to function at low pressure in those patients. In this study, we measured plasma levels of atrial and brain natriuretic peptide before and during the postoperative period in patients undergoing total cavopulmonary connection. METHODS: We evaluated 60 patients: 30 patients underwent total cavopulmonary connection and 30 patients underwent definitive repair for Fallot's tetralogy. Blood samples for measurement of atrial and brain natriuretic peptide were obtained before the operation and in the postoperative period. RESULTS: Plasma levels of atrial and brain natriuretic peptide were significantly lower during the early postoperative period in patients undergoing total cavopulmonary connection than in patients undergoing definitive repair for Fallot's tetralogy. No correlations were identified between the atrial natriuretic peptide levels and central venous pressure after total cavopulmonary connection. CONCLUSION: These results suggest that total cavopulmonary connection attenuates the secretion of atrial and brain natriuretic peptide in the early postoperative period. The suppressed release of atrial and brain natriuretic peptide after total cavopulmonary connection may have clinical importance.

Adolescent↗
PubMed2001

Myofascial force transmission causes interaction between adjacent muscles and connective tissue: effects of blunt dissection and compartmental fasciotomy on length force characteristics of rat extensor digitorum longus muscle.

Muscles within the anterior tibial compartment (extensor digitorum longus: EDL, tibialis anterior: TA, and extensor hallucis longus muscles: EHL) and within the peroneal compartment were excited simultaneously and maximally. The ankle joint was fixed kept at 90 degrees. For EDL length force characteristics were determined. This was performed first with the anterior tibial compartment intact (1), and subsequently after: (2) blunt dissection of the anterior and lateral interface of EDL and TA. (3) Full longitudinal lateral fasciotomy of the anterior tibial compartment. (4) Full removal of TA and EHL muscles. Length-force characteristics were changed significantly by these interventions. Blunt dissection caused a force decrease of approximately 10% at all lengths, i.e., without changing EDL optimum or active slack lengths. This indicates that intermuscular connective tissue mediates significant interactions between adjacent muscles. Indications of its relatively stiff mechanical properties were found both in the physiological part of the present study, as well as the anatomical survey of connective tissue. Full lateral compartmental fasciotomy increased optimum length and decreased active slack length, leading to an increase of length range (by approximately 47%), while decreasing optimal force. As a consequence an increase in force for the lower length range was found. Such changes of length force characteristics are compatible with an increased distribution of fiber mean sarcomere length. On the basis of these results, it is concluded that extramuscular connective tissue has a sufficiently stiff connection to intramuscular connective tissue to be able to play a role in force transmission. Therefore, in addition to intramuscular myofascial force transmission, extramuscular force transmission has to be considered within intact compartments of limbs. A survey of connective tissue structures within the compartment indicated sheet-like neuro-vascular tracts to be major components of extramuscular connective tissue with connections to intramuscular connective tissue stroma. Removal of TA and EHL yielded yet another decrease of force (mean for optimal force approximately 10%). No significant changes of optimum and active slack lengths could be shown in this case. It is concluded that myofascial force transmission should be taken into account when considering muscular function and its coordination, and in clinical decisions regarding fasciotomy and repetitive strain injury.

Animals↗