Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Forelimb”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 667 records · Page 37Linked to original sources
PubMed2006

Isometric contractile properties of sexually dimorphic forelimb muscles in the marine toad Bufo marinus Linnaeus 1758: functional analysis and implications for amplexus.

It has been shown in the bullfrog, Rana catesbeiana Shaw 1802, that certain forelimb muscles in males have different contractile properties when compared with females, which may result from adaptation for amplexus. We extended this study to a distantly related species, Bufo marinus Linnaeus 1758, by testing the isometric contractile properties of three muscles, abductor indicus longus (AIL), and flexor carpi radialis (FCR) (both dimorphic muscles), and extensor carpi ulnaris (ECU) (non-dimorphic control). In males the dimorphic muscles had greater wet mass and cross-sectional area than in the females, and also produced significantly greater isometric force. As in bullfrogs, however, the maximum tetanic force per cm(2) of muscle cross-section did not differ between the sexes. In spite of this similarity in maximum force, the two dimorphic muscles were much less fatigable in the males than in the females. Lower fatigability in males correlated with exceptionally elongated relaxation times that maintained high levels of force between stimulus trains. This sustained force was negligible in the females, suggesting that this feature may allow males to maintain amplexus for prolonged periods. The same sustained force response was observed in the earlier study of Rana catesbeiana. Because this response is similar in Bufo and Rana, muscular properties correlated with amplexus may be shared across anurans by inheritance of this response from a common ancestor.

Analysis of Variance↗
PubMed1978

An electromyographic analysis of forelimb muscles during overground stepping in the cat.

The patterns of activity of 33 forelimb muscles during unrestrained overground stepping in eight adult cats were analysed using intramuscular electromyography. Three general patterns were found. Some muscles began activity during the first extension epoch (E1) and ceased near the end of the third extension epoch (E3) and were considered extensors. Others, considered flexors, began activity just prior to the flexion (F) epoch and ceased at or just after the onset of E1. Other muscles showed a biphasic pattern of activation; one period of activity occurring during F, the other during the extension epochs. In all regions of the limb, individual muscles displayed variation in the onset and time course of activity. The results are interpreted in terms of a model of locomotor generation which proposes specific neural output to individual muscles. Muscles of the shoulder region are proposed to act mainly to produce translatory and rotatory movements of the scapula associated with lengthening the step. Muscles of the elbow region and antebrachium are interpreted as playing roles both in producing flexion-extension movements and in the absorption of energy. The latter group are considered especially suitable to energy absorption because of their pennate arrangement of muscle fasciculi and their long tendons.

Animals↗
PubMed2004

Role of spike timing in the forelimb somatosensory cortex of the rat.

The aim of this study was to test the hypothesis that the significance of spike timing in somatosensory processing is not a specific feature of the whisker cortex but a more general characteristic of the primary somatosensory cortex. We recorded ensembles of neurons using microwire arrays implanted in the deep layers of the forelimb region of the rat primary somatosensory cortex in response to step stimuli delivered to the cutaneous surface of the contralateral body. We used a recently developed peristimulus time histogram (PSTH)-based classification method to investigate the temporal precision of the code by evaluating how changing the bin size (from 40 to 1 msec) would affect the ability of the ensemble responses to discriminate stimulus location on a single-trial basis. The information related to the discrimination was redundantly distributed within the ensembles, and the ability to discriminate stimulus location increased when decreasing the bin size, reaching a maximum at 4 msec. In our experiment, at 4 msec bin size the first spike per neuron after the stimulus conveyed almost as much information as the entire responses, so the temporal precision of the code was preserved in the first spikes. Subsequent spikes were less frequent but conveyed more information per spike. Finally, not only the trials correctly classified but also the trials incorrectly classified conveyed information about stimulus location with a similar temporal precision. We conclude that the role of spike timing in cortical somatosensory processing is not an exclusive feature of the highly specialized rat trigeminal system, but a more general property of the rat primary somatosensory cortex.

Action Potentials↗
PubMed2006

Synaptic bombardment modulates muscarinic effects in forelimb motor cortex.

Neocortical neurons in vivo exist in an environment of continuous synaptic bombardment, receiving a complex barrage of excitatory and inhibitory inputs. This background activity (by depolarizing neurons, increasing membrane conductance, and introducing fluctuations) strongly alters many aspects of neuronal responsiveness. In this study, we asked how it shapes neuromodulation of postsynaptic responses. Specifically, we examined muscarinic modulation of forelimb motor cortex, a brain area in which cholinergic stimulation is known to be necessary for modifications during motor skill learning. Using a dynamic clamp system to inject simulated conductances into pyramidal neurons in motor cortical slices, we mimicked in vivo-like activity by introducing a random background of excitatory and inhibitory inputs. When muscarinic receptors were stimulated with the agonist oxotremorine-M, several previously described currents were modified, and excitability was increased. However, the presence of the background conductances strongly attenuated most muscarinic agonist effects, with the notable exception that sustained firing responses to trains of inputs were well preserved. This may be important for promoting plasticity in vivo.

Action Potentials↗
PubMed2005

A gene(s) for all-trans-retinoic acid-induced forelimb defects mapped and confirmed to murine chromosome 11.

All-trans-retinoic acid (RA) induces various anatomical limb dysmorphologies in mice dependent on the time of exposure. During early limb development, RA induces forelimb ectrodactyly (digital absence) with varying susceptibilities for different inbred mouse strains; C57BL/6N are highly susceptible while SWV are resistant. To isolate the genetic basis of this defect, a full-genome scan was performed in 406 backcross fetuses of F(1) males to C57BL/6N females. Fetuses were exposed via a maternal injection of 75 mg of RA per kilogram of body weight on gestational day 9.25. The genome-wide analysis revealed significant linkage to a chromosome 11 locus near D11Mit39 with a maximum LOD score of 9.0 and to a chromosome 4 locus near D4Mit170. An epistatic interaction was detected between loci on chromosome 11 (D11Mit39) and chromosome 18 (D18Mit64). Linkage to the chromosome 11 locus (D11Mit39) was confirmed in RA-treated backcross fetuses of F(1) females to C57BL/6N males. Loci associated with bone density/mass in both human and mouse were previously detected in the same region, suggesting a mechanistic linkage with bone homeostasis. The human syntenic region of this locus has been previously linked to Meckel syndrome; the phenotype includes postaxial polydactyly, an ectopic digital defect hypothesized to be induced by a common molecular pathway with ectrodactyly.

Animals↗
PubMed1980

[Methods for intravenous injection and blood collection in the guinea pig via veins of the forelimb without anesthesia (author's transl)].

Methods for intravenous injection and blood collection by way of the forelimb in guinea pigs without anesthesia were investigated, with the results as follows: 1) Both the accessory cephalic and cephalic veins were found available for injection as well as for drawing blood samples. Venipuncture was accomplished with greater ease by using the accessory cephalic vein. 2) The following procedure has proven practical. (i) Clip the hair over the site. (ii) Restrain the animal to immobilize the foreleg in slight extension by grasping it at the elbow joint with the thumb and forefinger over its dorsal and ventral aspects, respectively. (iii) After disinfecting the skin surface with alcohol, perform injection using an appropriate syringe with a 27 (1/4) or 25 (1/3) gauge intravenous needle, or puncture the vein with a 23 (1/2) gauge i. v. needle to collect the blood that drips out.

Animals↗
PubMed1992

Activity of cervical neurons during forelimb fictive locomotion in decerebrate cats.

Unit activities were recorded from cervical neurons during forelimb fictive locomotion. Rhythmic activities were evaluated by onset and termination. Rhythmically-active neurons were classified into 4 major groups: (1) neurons, the active periods covered the whole flexor phase; (2) f+e neurons, the active periods commenced prior to and terminated in the extensor phase; (3) e neurons, the active periods appeared within the extensor phase; (4) e+f neurons, the active periods commenced prior to and terminated in the flexor phase. In addition, a few neurons that were not classified were observed. Neuronal behaviors seemed to suggest that and e+f were grouped "flexor-like," while e and f+e were grouped as "extensor-like." "Flexor-like" neurons were likely distributed in the dorsal (lamina V-VI) and rostral (C5-C6) region, whereas "extensor-like" neurons distributed mainly in the ventral (lamina VI-VII) and caudal (C7-T1) region. Some neurons showed rhythmic activities prior to appearance of fictive locomotion (prelude rhythm). The structure of the central pattern generator was discussed.

Animals↗
PubMed2001

Sensitivity analysis and application to trotting of a noninvasive method to calculate flexor tendon forces in the equine forelimb.

OBJECTIVE: To test the sensitivity to measurement and modeling errors of a method for noninvasive calculation of flexor tendon forces in the equine forelimb and to calculate tendon forces for Dutch Warmblood horses during trotting. SAMPLE POPULATION: A normative set of kinematic and ground-reaction force (GRF) data obtained from horses during trotting in another study. PROCEDURE: Forces in the flexor tendons were calculated from the data set before and after addition of fixed relative and absolute errors. Amount of error was based on normal accuracy of the variables. A similar analysis was performed for a measure of strain of the accessory ligament of the deep digital flexor tendon. RESULTS: The only errors that had a substantial influence on accuracy were modeling errors in the mechanical properties of the suspensory ligament and measurement errors in the point of application of the GRF and position of the marker on the distal interphalangeal joint. Influence of the measurement errors could be minimized by applying usual correction methods. CONCLUSIONS AND CLINICAL RELEVANCE: After correction of measurement errors, the method can be used to calculate mean tendon forces for a group of horses and to evaluate the influence of factors such as surface properties, type of shoe, speed, and fatigue on tendon forces. The method could become an important tool for use in research on the cause, prevention, and treatment of tendon injuries in horses.

Animals↗
PubMed2003

Evaluation of a stochastic Markov-chain model for the development of forelimb injuries in Thoroughbred racehorses.

OBJECTIVE: To evaluate a Markov-chain model for the development of forelimb injuries in Thoroughbreds and to use the model to determine effects of reducing sprint distance on incidence of metacarpal condylar fracture (CDY) and severe suspensory apparatus injury (SSAI). SAMPLE POPULATION: Weekly exercise and injury data for 122 Thoroughbreds during racing or training. PROCEDURE: Weekly data were used to construct a Markov-chain model with 5 states (uninjured [UNINJ], palpable suspensory apparatus injury [PSAII, SSAI, CDY, and lost to follow-up [LOST]). Transition probabilities between UNINJ and PSAI were estimated as a function of weekly sprint distance by use of linear regression analysis. The model was used to predict distributions of annual CDY and SSAI incidences in southern California racehorses and was validated by using CDY incidence reported by racetrack practitioners. The model was modified by reducing the number of sprint distances that were > 6 furlongs (> 1.20 km) by 20%, and CDY and SSAI incidences were compared with those generated by the baseline model. RESULTS: The model accurately fit development of injuries in the sample population but overestimated development of injuries in the southern California racehorse population. Development of and recovery from PSAI were correlated with distance run at high speeds. Reducing by 20% the number of sprints run at distances > 6 furlongs significantly reduced modeled annual CDY and SSAI incidence by 9%. CONCLUSIONS AND CLINICAL RELEVANCE: Reducing the number of sprints at distances > 6 furlongs, particularly among horses with PSAI, reduces risk of CDY and SSAI.

Animals↗
PubMed2004

Effects of injury to the suspensory apparatus, exercise, and horseshoe characteristics on the risk of lateral condylar fracture and suspensory apparatus failure in forelimbs of thoroughbred racehorses.

OBJECTIVE: To assess concurrently the effects of moderate ligamentous suspensory apparatus injury (MLSAI), racing-speed exercise, and horseshoe characteristics on risk of catastrophic suspensory apparatus failure (SAF) or metacarpal condylar fracture (CDY) in forelimbs of racehorses. SAMPLE POPULATION: Cadavers of 301 Thoroughbred racehorses (108 with SAF, 33 with CDY and 160 control horses). PROCEDURE: A cross-sectional epidemiologic study was used to describe distributions and relationships between MLSAI, exercise, and horseshoe variables. Logistic regression was used to assess potential risk factors for developing SAF and CDY. RESULTS: Exercise variables were more highly associated with age than height of a steel bar affixed to the ground surface of the front of a horseshoe (ie, toe grab) or sex. Marginal associations were detected between MLSAI and age and height of toe grab. Higher risk for developing SAF was associated with MLSAI, use of a pad on a horseshoe, longer interval since last period of > or = 60 days without a race or timed workout (ie, layup), 2 to 5 career races, and higher intensity of recent exercise. Higher risk for developing CDY was associated with MLSAI, male horses, age between 2 and 5 years, higher intensity of recent exercise, and longer interval since layup. CONCLUSIONS AND CLINICAL RELEVANCE: Recognition of MLSAI and rehabilitation of affected horses should reduce incidence of SAF and CDY. Horses in longterm continuous training with recent high-intensity exercise are at greater risk for injury. Use of pads in horseshoes was associated with SAF, although the relationship may not be causal.

Age Factors↗
PubMed2004

Observer variation in visual assessment of forelimb horseshoe characteristics on Thoroughbred racehorses.

OBJECTIVE: To assess the accuracy and reliability of a visual method of evaluating horseshoe characteristics. ANIMALS: 1,199 Thoroughbred racehorses. PROCEDURE: Characteristics of 1 forelimb horseshoe were visually assessed on horses immediately prior to racing by 5 field observers at 5 major racetracks in California. Characteristics evaluated included horseshoe type; toe grab height; and the presence of a rim, pad, and heel traction devices. Sensitivity and specificity for observer assessment of horseshoe characteristics were calculated by comparing observer assessments to a postmortem laboratory standard for horses that died within 48 hours of a race. Intraobserver agreement was assessed in a subset of horses by comparing horseshoe observations made before and after the horse's race. Interobserver agreement was evaluated by comparing horseshoe assessment among observers who examined the same subset of horses prior to racing on select days. RESULTS: The sensitivity and specificity of this visual method of evaluating horseshoe characteristics were good and ranged from 0.75 to 1 and 0.67 to 1, respectively. Agreement beyond chance (weighted kappa values) between observers and the laboratory standard for toe grab height was fair (0.60 to 0.62). Intraobserver and interobserver agreements (kappa values) were high (0.86 to 0.99 and 0.71 to 1, respectively). CONCLUSIONS AND CLINICAL RELEVANCE: Visual observation of horseshoes can be a feasible and reproducible method for assessing horseshoe characteristics prospectively in a large cohort of horses under racing conditions.

Animals↗
PubMed2006

Association between findings on palmarodorsal radiographic images and detection of a fracture in the proximal sesamoid bones of forelimbs obtained from cadavers of racing Thoroughbreds.

OBJECTIVE: To determine the distribution for limbs and bones in horses with fractures of the proximal sesamoid bones and relationships with findings on palmarodorsal radiographic images. SAMPLE POPULATION: Proximal sesamoid bones obtained from both forelimbs of cadavers of 328 racing Thoroughbreds. PROCEDURE: Osteophytes; large vascular channels; and fracture location, orientation, configuration, and margin distinctness were categorized by use of high-detail contact palmarodorsal radiographs. Distributions of findings were determined. Relationships between radiographic findings and fracture characteristics were examined by use of chi2 and logistic regression techniques. RESULTS: Fractures were detected in 136 (41.5%) horses. Biaxial fractures were evident in 109 (80%) horses with a fracture. Osteophytes and large vascular channels were evident in 266 (81%) and 325 (99%) horses, respectively. Medial bones typically had complete transverse or split transverse simple fractures, indistinct fracture margins, > 1 vascular channel that was > 1 mm in width, and osteophytes in abaxial wing and basilar middle or basilar abaxial locations. Lateral bones typically had an oblique fracture and distinct fracture margins. Odds of proximal sesamoid bone fracture were approximately 2 to 5 times higher in bones without radiographic evidence of osteophytes or large vascular channels, respectively. CONCLUSIONS AND CLINICAL RELEVANCE: Biaxial fractures of proximal sesamoid bones were common in cadavers of racing Thoroughbreds. Differences between medial and lateral bones for characteristics associated with fracture may relate to differences in fracture pathogeneses for these bones. Osteophytes and vascular channels were common findings; however, fractures were less likely to occur in bones with these features.

Age Distribution↗
PubMed2006

Development and evaluation of a noninvasive marker cluster technique to assess three-dimensional kinematics of the distal portion of the forelimb in horses.

OBJECTIVE: To develop and evaluate a marker cluster set for measuring sagittal and extrasagittal movement of joints in the distal portion of the forelimb in ponies. ANIMALS: 4 ponies. PROCEDURES: 5 infrared cameras were positioned on a concrete walkway in a frontal-sagittal arc and calibrated. Four segments were defined: hoof, middle phalanx, proximal phalanx, and metacarpus. Rigid clusters with 4 retroreflective markers were placed on each segment. A static trial was recorded with additional anatomic markers on the medial and lateral joint lines. Those anatomic markers were removed, and kinematic data were recorded at 240 Hz during walking. An ensemble mean was computed from the 4 ponies from 5 replicates of the walks. Joint kinematic variables were calculated by use of the calibrated anatomical system technique. The design and error dispersion of each marker were evaluated. RESULTS: Marker clusters were quasiplanar, but variation in orientation error was reduced because the mean radii were > 10 times the largest error dispersion values. Measurements of sagittal rotations of the distal interphalangeal, proximal interphalangeal, and metacarpophalangeal joints were similar to measurements obtained with bone-fixed triads, but larger discrepancies between the 2 methods were found for extrasagittal rotations. CONCLUSIONS AND CLINICAL RELEVANCE: Development of noninvasive methods for quantifying data pertaining to 3-dimensional motion in horses is important for advancement of clinical analysis. The technique used in the study enabled identification of flexion-extension motions with an acceptable degree of accuracy. Appropriate correction algorithms and improvements to the technique may enable future quantification of extrasagittal motions.

Animals↗
PubMed2001

Joint moments in the distal forelimbs of jumping horses during landing.

Tendon injuries are an important problem in athletic horses and are probably caused by excessive loading of the tendons during demanding activities. As a first step towards understanding these injuries, the tendon loading was quantified during jump landings. Kinematics and ground reaction forces were collected from the leading and trailing forelimbs of 6 experienced jumping horses. Joint moments were calculated using inverse dynamic analysis. It was found that the variation of movement and loading patterns was small, both within and between horses. The peak flexor joint moments in the coffin and fetlock joints were larger in the trailing limb (-0.62 and -2.44 Nm/kg bwt, respectively) than in the leading limb (-0.44 and -1.93 Nm/kg bwt, respectively) and exceeded literature values for trot by 82 and 45%. Additionally, there was an extensor coffin joint moment in the first half of the stance phase of the leading limb (peak value 0.26+/-0.18 Nm/kg bwt). From these results, it was concluded that the loading of the flexor tendons during landing was higher in the trailing than in the leading limb and that there was an unexpected loading of the extensor tendon in the leading limb.

Animals↗
PubMed2002

A description of the motion of the navicular bone during in vitro vertical loading of the equine forelimb.

Motion of the navicular bone might play a role in the development of navicular disease in horses but is difficult to asses. In the present study, 3-dimensional motion of this bone was determined using roentgen stereophotogrammetric analysis. Tantalum pellets were inserted, in vitro, in the bones of 6 forelimbs of mature Shetland ponies and kinematics were measured during vertical loading up to 2 kN. The motions of the navicular bone and coffin joint were limited to flexion/extension, there were no substantial out-of-plane motions. There was only little flexion between the navicular bone and the coffin bone, which was correlated (r = 0.66) with coffin joint flexion. There was substantial flexion between the navicular bone and the short pastern, which was highly correlated with coffin joint flexion (r = 0.97). We conclude that the navicular bone, generally, follows the coffin bone during coffin joint flexion, although there are small but consistent motions between the navicular bone and the coffin bone. These motions might play a role in the development of navicular disease in horses.

Animals↗
PubMed2004

Influence of support boots on fetlock joint angle of the forelimb of the horse at walk and trot.

REASONS FOR PERFORMING STUDY: Support boots are thought to reduce tension on the superficial digital flexor tendon (SDTF) of the horse and are frequently recommended for horses convalescing after tendonitis, but evidence of their effectiveness is conflicting. OBJECTIVE: To document the effects of 4 different types of support boots on fetlock joint angle in comparison to the unprotected fetlock. METHODS: In 26 horses, the kinematics of the forelimb fetlock joint angle was measured at walk and trot on a treadmill when wearing 3 different types of support boots and 1 protective boot, as well as without boots. As outcome parameters, maximum extension of the fetlock joint and the moment at which maximum extension occurred in the stride cycle were determined. RESULTS: At walk, 2 of the support boots reduced the maximum extension significantly by 0.8 and 0.9 degrees, respectively (P<0.05). Additionally, one type of boots also delayed the occurrence of maximal extension within the stride cycle. At trot, all support boots reduced maximum extension significantly by 0.56-1.44 degrees (P<0.01), and the protective boot reduced maximum extension by 0.56 degrees (P<0.05). CONCLUSIONS AND POTENTIAL RELEVANCE: The results demonstrate the effectiveness of support boots in reducing maximum extension of the fetlock, which can be assumed to reduce tension in the suspensory apparatus and SDFT. The delay of the moment of maximal extension may be relevant in reducing dynamic forces. However, it should be noted that the long-term consequences of reduction of maximum fetlock extension are still uncertain. Such a reduction over a prolonged period might negatively affect fibre alignment in the healing tendon.

Animals↗
PubMed2004

Effects of 6 degree elevation of the heels on 3D kinematics of the distal portion of the forelimb in the walking horse.

REASONS FOR PERFORMING STUDY: Understanding of the biomechanical effects of heel elevation remains incomplete because in vivo studies performed with skin markers do not measure the actual movements of the 3 digital joints. OBJECTIVE: To quantify the effects of 6 degree heel wedge on the 3-dimensional movements of the 4 distal segments of the forelimb in the walking horse. METHODS: Four healthy horses were used. Kinematics of the distal segments was measured invasively with a system based on ultrasonic triangulation. Three-dimensional rotations of the digital joints were calculated by use of a 'joint coordinate system' (JCS). Data obtained with heel wedges were compared to those obtained with standard shoes during the stance phase of the stride. RESULTS: Heel wedges significantly increased maximal flexion of the proximal (PIPJ) and distal (DIPJ) interphalangeal joints and maximal extension (mean +/- s.d. +0.8 +/- 0.3 degrees) of the metacarpophalangeal joint (MPJ). Extension of the PIPJ and DIPJ was decreased at heel-off. Few effects were observed in extrasagittal planes of movement. CONCLUSIONS: Heel wedges affect the sagittal plane kinematics of the 3 digital joints. POTENTIAL RELEVANCE: Controversial effects previously observed on the MPJ may be explained by the substantial involvement of the PIPJ, which was wrongly neglected in previous studies performed on the moving horse.

Animals↗
PubMed1977

Alteration of plasma hypoxanthine concentration during ischaemia in the forelimb of the pig.

Ischaemia in the forelimb of pigs was induced by clamping the main artery of an 'isolated leg' preparation. In plasma from the brachial vein the hypoxanthine concentration increased linearly between 10 and 25 min of ischaemia. The average increase in plasma hypoxanthine concentration in ten experiments was 25-0 micromol/1 after 30 min of ischaemia. It is concluded that the plasma hypoxanthine level might be a useful indicator of tissue hypoxia caused by impairment of peripheral blood flow.

Animals↗