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At least 19 recordsLinked to original sources

PubMed2002

Arm blood flow and metabolism during arm and combined arm and leg exercise in humans.

The cardiovascular response to exercise with several groups of skeletal muscle suggests that work with the arms may decrease leg blood flow. This study evaluated whether intense exercise with the legs would have a similar effect on arm blood flow (Y(arm)) and O(2) consumption (V(O(2))(,arm)). Ten healthy male subjects (age 21 +/- 1 year; mean +/- S.D.) performed arm cranking at 80 % of maximum arm work capacity (A trial) and combined arm cranking with cycling at 60 % of maximum leg work capacity (A + L trial). The combined trial was a maximum effort for 5-6 min. Y(arm) measurement by thermodilution in the axilliary vein and arterial and venous blood samples permitted calculation of V(O(2))(,arm). During the combined trial, Y(arm) was reduced by 0.58 +/- 0.25 l min(-1) (19.1 +/- 3.0 %, P < 0.05) from the value during arm cranking (3.00 +/- 0.46 l min(-1)). The arterio-venous O(2) difference increased from 122 +/- 15 ml l(-1) during the arm trial to 150 +/- 21 ml l(-1) (P < 0.05) during the combined trial. Thus, V(O(2))(,arm) (0.45 +/- 0.06 l min(-1)) was reduced by 9.6 +/- 6.3 % (P < 0.05) and arm vascular conductance from 27 +/- 4 to 23 +/- 3 ml min(-1) (mmHg)(-1) (P < 0.05) as noradrenaline spillover from the arm increased from 7.5 +/- 3.5 to 13.8 +/- 4.2 nmol min(-1) (P < 0.05). The data suggest that during maximal whole body exercise in humans, arm vasoconstriction is established to an extent that affects oxygen delivery to and utilisation by working skeletal muscles.

Adult↗

PubMed2003

Arm blood flow and oxygenation on the transition from arm to combined arm and leg exercise in humans.

The cardiovascular response to exercise with several groups of skeletal muscle implies that work with the legs may reduce arm blood flow. This study followed arm blood flow (Yarm) and oxygenation on the transition from arm cranking (A) to combined arm and leg exercise (A+L). Seven healthy male subjects performed A at approximately 80 % of maximum work rate (Wmax) and A at ~80 % Wmax combined with L at approximately 60 % Wmax. A transition trial to volitional exhaustion was performed where L was added after 2 min of A. The Yarm was determined by constant infusion thermodilution in the axillary vein and changes in biceps muscle oxygenation were measured with near-infrared spectroscopy. During A+L Yarm was lowered by 0.38 +/- 0.06 l min-1 (10.4 +/- 3.3 %, P < 0.05) from 2.96 +/- 1.54 l min-1 during A. Total (HbT) and oxygenated haemoglobin (HbO2) concentrations were also lower. During the transition from A to A+L Yarm decreased by 0.22 +/- 0.03 l min-1 (7.9 +/- 1.8 %, P < 0.05) within 9.6 +/- 0.2 s, while HbT and HbO2 decreased similarly within 30 +/- 2 s. At the same time mean arterial pressure and arm vascular conductance also decreased. The data demonstrate reduction in blood flow to active skeletal muscle during maximal whole body exercise to a degree that arm oxygen uptake and muscle tissue oxygenation are compromised.

Adult↗

PubMed2004

Arm-crank propelled three-wheeled chair: physiological evaluation of the propulsion using one arm and both arm patterns.

Disabled people in India frequently use the arm-crank propelled three-wheeled chair (ACWC) for outdoor transportation. Two models of these chairs are commercially available: one is powered by cranking using one arm (ACWC-1) and the other uses both arms (ACWC-2). The purpose of the study was to compare the efficiency of the two types of propulsion with respect to the standard physiological responses and, consequent upon the findings, to recommend the use of a suitable one. The energetics of locomotion of the users at their freely chosen speed (FCS) were measured and compared with changes in the physiological parameters in the within-subject groups. The study was conducted in outdoor settings to simulate the actual locomotive conditions encountered by the users in their practical life. 14 males, who had been regular and proficient users of both propulsion systems for more than last six years and who had a history of paraplegia (below the 10th thoracic vertebra, n=11) and poliomyelitis (n=3) participated in the study. The subjects were required to propel the test chair (a combination of both the propulsion systems built in a single model) on an oval track of 358 m circumference at their FCS for 5 min; ambulatory data were collected during last 3 min of exercise and averaged. The FCS (m/min), heart rates (bpm) and oxygen uptake (l/min) were measured. Physiological cost index (b/m) oxygen consumption (ml/kg/min), oxygen cost (ml/kg/m) and net locomotor energy cost (kcal/kg/km) of the two sets of observations were derived and compared using a t-test for the paired observations. The FCS was significantly higher and the physiological parameters were lower with the ACWC-2 than with ACWC-1, except for heart rate and oxygen consumption, where the difference was not significant . It is concluded that two-arm use is more efficient and less physically demanding than one-arm use in the arm-crank propulsion system and that the former is more suitable for efficient ambulation.

Adult↗

PubMedDate not supplied

[Interchangeability among the percentages of body fat estimated by mid-arm adipose area, triceps skinfold thickness and arm-to-arm segmental bioimpedance analysis].

BACKGROUND: Assessing nutritional status based on the upper limbs is useful at the clinical level. The aim of this study is to evaluate the agreement degree of the body fat percentages (%BF) estimated by the mid-arm adipose area (%BFARM), the Siri triceps skin-fold equation (%BFTRICEPS) and the arm-to-arm segmental bioimpedance analysis (%BFBIA), as well as the Siri four-skinfold equation (%BFSIRI), assessing their interchangeability. METHODS: A cross-sectional study. Body fat assessments were made on a total of 145 subjects (83 males, 62 females) anthropometrically and by bioelectrical impedance analysis (Omron BF 300). The agreement between methods were analyzed using the interclass correlation coefficient (ICC) and the Bland-Altman method. RESULTS: The ICC between %BFARM and %BFTRICEPS was 0.8322 (CI .95% 0.7672-0.8791); between %BFARM-%BFBIA 0.7337 (0.6305-0.8080) and between %BFTRICEPS-%BFBIA 0.9290 (0.9015; 0.9488). For the Bland-Altman method, the agreement interval between %BFARM-%BFTRICEPS (-11.2; 16.96) and between %BFARM-%BFBIA (-13.04; 21.76) exceeded the cutoff point (+/- 10%), but not between %BFTRICEPS-%BFBIA (-6.64; 9.6), %BFSIRI-%BFTRICEPS (-5.27; 4.52) and %BFSIRI-%BFBIA (-6.31; 8.52). The BMI has no bearing on the results. CONCLUSIONS: The method utilized influences the nutritional assessment made based on the upper limbs. The mid-arm adipose area method overestimated the %BF with relationship to the Siri triceps skinfold or four-skinfold equation and to the bioelectrical impedance analysis, and although this result suggests that mid-arm adipose area may not be a good indicator of global adiposity, this must be confirmed against a gold standard.

Adipose Tissue↗

PubMedDate not supplied

[Relations among arm, arm muscle, arm fat areas and menarche in adolescents in the municipality of Botucatu].

The authors show the relations among arm circumference, arm muscle and arm fat areas with or without menarche, by carrying out an anthropometric study in 717 adolescents in the municipality of Botucatu. It must be emphasized that those adolescents who had already menstruated presented significantly higher nutritional indicators than those who had not menstruated yet. There was an increase in fat tissue and lean body mass in those adolescents who had already menstruated. Body changes might be expressed by calculating muscle and arm fat areas using triceps skinfold and arm circumference.

English Abstract↗

PubMed2004

Multiple variations of the deep artery of arm: double deep artery of arm and deep artery of arm with the superior ulnar collateral artery. A case report.

Multiple variations of the deep artery of arm were observed during routine gross anatomic dissection of the right upper extremity of a 54-year-old male cadaver. In this case study, a double deep artery of arm and the deep artery of arm with the superior ulnar collateral artery were reported. The anatomic origin of the deep artery of arm is variable. In the literature, a double deep brachialis since its origin is reported in 0.7% and the deep brachial with the superior ulnar collateral artery in 22.3%. Such variations are considered to be occurring during embryologic development. These type of variations are important both in surgical and clinical situations.

Brachial Artery↗

PubMed1990

The relative accuracy of simultaneous same arm, simultaneous opposite arm and sequential same arm measurements in the validation of automated blood pressure measuring devices.

With the increasing demand for accurate BP measuring devices there comes also the need for validation. Most validation procedures assess the accuracy of a test device against a known standard, most commonly a mercury sphygmomanometer. The best method for assessing device accuracy is to measure BP simultaneously in the same arm with the test device and a mercury sphygmomanometer. This is not always possible because the deflation mechanism of the test device interferes with the ability of an observer to auscultate the Korotkov sounds accurately. In this study a mathematical method of sequential comparison between the test device and a mercury standard in the same arm is described which is almost as accurate as simultaneous measurement in the same arm.

Adult↗

PubMed1996

Self-moved target eye tracking in control and deafferented subjects: roles of arm motor command and proprioception in arm-eye coordination.

1. When a visual target is moved by the subject's hand (self-moved target tracking), smooth pursuit (SP) characteristics differ from eye-alone tracking: SP latency is shorter and maximal eye velocity is higher in self-moved target tracking than in eye-alone tracking. The aim of this study was to determine which signals (motor command and/or proprioception) generated during arm motion are responsible for the decreased time interval between arm and eye motion onsets in self-moved target tracking. 2. Six control subjects tracked a visual target whose motion was generated by active or passive movements of the observer's arm in order to determine the role played by arm proprioception in the arm-eye coordination. In a second experiment, the participation of two subjects suffering complete loss of proprioception allowed us to assess the contribution of arm motor command signals. 3. In control subjects, passive movement of the arm led to eye latencies significantly longer (130 ms) than when the arm was actively self-moved (-5 ms:negative values meaning that the eyes actually started to move before the target) but slightly shorter than in eye-alone tracking (150 ms). These observations indicate that active movement of the arm is necessary to trigger short-latency SP of self-moved targets. 4. Despite the lack of proprioceptive information about arm motion, the two deafferented subjects produced early SP (-8 ms on average) when they actively moved their arms. In this respect they did not differ from control subjects. Active control of the arm is thus sufficient to trigger short-latency SP. However, in contrast with control subjects, in deafferented subjects SP gain declined with increasing target motion frequency more rapidly in self-moved target tracking than in eye-alone tracking. 5. The deafferented subjects also tracked a self-moved target while the relationship between arm and target motions was altered either by introducing a delay between arm motion and target motion or by reversing target motion relative to arm motion. As with control subjects, delayed target motion did not affect SP latency. Furthermore, the deafferented subjects adapted to the reversed arm-target relationship faster than control subjects. 6. The results suggest that arm motor command is necessary for the eye-to-arm motion onset synchronization, because eye tracking of the passively moved arm was performed by control subjects with a latency comparable with that of eye-alone tracking of an external target. On the other hand, as evidenced by the data from the deafferented subjects, afferent information does not appear to be necessary for reducing the time between arm motion and SP onsets. However, afferent information appears to contribute to the parametric adjustment between arm motor command and visual information about arm motion.

Adult↗

PubMed2004

Mid-arm circumference and mid-arm/head circumference ratio in term newborns.

CONTEXT: Mid-arm circumference of the newborn is strongly associated with birth weight and is a very good indicator of low and insufficient birth weight. However, there are few Brazilian studies on the relationship between mid-arm and head circumferences and, thus, this does not form part of the routine evaluation for newborns. OBJECTIVES: To establish the mid-arm circumference and mid-arm/head circumference ratio in a population of term newborns. TYPE OF STUDY: Cross-sectional study carried out between June 1997 and August 1999. SETTING: Hospital Maternidade Leonor Mendes de Barros, São Paulo. PARTICIPANTS: Term newborns (66 males and 65 females) of appropriate growth for gestational age, whose mothers were healthy, were included in the study. MAIN MEASUREMENTS: Arm circumference, arm circumference/head circumference ratio, birth weight and gestational age were measured within 48 hours of birth. Data were considered significant when p < 0.01. RESULTS: The mean values for the mid-arm circumference were 10.76 cm (standard deviation, SD = 0.68) for females and 10.76 (SD = 0.81) for males. The mean value for the mid-arm/head circumference ratio was 0.31 (SD = 0.02) for both sexes. Mid-arm circumference values were significantly related to birth weight and gestational age, whereas mid-arm/head circumference ratio was related only to birth weight. CONCLUSIONS: Mid-arm circumference and mid-arm/head circumference ratio values were established for the studied population. It was possible to obtain curves for both mid-arm circumference and mid-arm/head circumference ratio in relation to birth weight. However, for mid-arm circumference, it was only possible to obtain curves in relation to gestational age. The use of the regression curves did not seem powerful enough to predict the mid-arm circumference and mid-arm/head circumference ratio in this population of term newborns. There were no gender differences for either of the measurements studied.

Anthropometry↗

PubMed1994

The relation between upper arm dimensions and maximal oxygen uptake during arm exercise.

The relationship between upper arm dimensions and maximal oxygen uptake (VO2peak) during arm exercise was investigated. Nineteen almost untrained male subjects (22 +/- 2 yrs, 183 +/- 5.5 cm, 74 +/- 7.5 kg; mean +/- SD) volunteered to take part in the study. The following anthropometrical upper arm data were obtained for each subject: upper arm circumference, biceps and triceps skinfold thickness, upper arm length. From these data the cross-sectional area of the muscles, of the muscles plus bone of the upper arm, and the upper arm muscle volume were calculated. Upper arm volume was determined by water immersion. The subjects performed arm cranking with an increasing load of 10 watt each minute (Wpeak 125 +/- 17.4 watt, VO2peak: 2.54 +/- 0.33 l/min; mean +/- SD). Multiple regression analyses showed that VO2peak could be best explained by the cross-sectional area of the muscles plus bone of the upper arm (r = 0.65, p < 0.005). Other factors did not add significantly. The variables as body mass, fatfree body mass, upper arm volume and total arm volume correlated less well with VO2peak (r < 0.5). In conclusion it is suggested to use the easily obtainable cross-sectional area of the muscles plus bone of the upper arm to standardize VO2peak of arm cranking.

Adult↗

PubMed2005

Arm exercise and hyperinflation in patients with COPD: effect of arm training.

BACKGROUND: Unlike studies on leg exercise, reports on the regulation of dynamic hyperinflation during arm exercise are scanty. We ascertained the following in patients with COPD: (1) whether and to what extent upper-limb exercise results in dynamic hyperinflation, and (2) the mechanism whereby an arm-training program (ATP) reduces arm effort and dyspnea. PATIENTS: Twelve patients with moderate-to-severe COPD were tested during incremental, symptom-limited arm exercise after a non-intervention control period (pre-ATP) and after ATP. METHODS: Exercise testing (1-min increments of 5 W) was performed using an arm ergometer. Oxygen uptake (V(O2)), carbon dioxide output, minute ventilation (Ve), tidal volume, and respiratory rate (RR) were measured continuously during the tests. Inspiratory capacity (IC), exercise dyspnea, and arm effort using a Borg scale were assessed at each step of exercise. RESULTS: Arm exercise resulted in a significant decrease in IC and significant positive relationships of IC with an increase in V(O2) and exercise dyspnea and arm effort. The results of ATP were as follows: (1) a significant increase in exercise capacity (p < 0.001); (2) no change in the relationships of exercise dyspnea and arm effort with Ve and IC, and of IC with V(O2); (3) at a standardized work rate, Ve, exercise dyspnea, and arm effort significantly decreased, while the decrease in IC was significantly less (p < 0.01) than before the ATP; the decrease in Ve was accomplished primarily by a decrease in RR; and (4) at standardized Ve, exercise dyspnea and arm effort decreased significantly. CONCLUSIONS: Arm exercise results in the association of dynamic hyperinflation, exercise dyspnea, and arm effort in COPD patients. An ATP increases arm endurance, modulates dynamic hyperinflation, and reduces symptoms.

Aged↗

PubMed1991

Assembly and characterization of five-arm and six-arm DNA branched junctions.

DNA branched junctions have been constructed that contain either five arms or six arms surrounding a branch point. These junctions are not as stable as junctions containing three or four arms; unlike the smaller junctions, they cannot be shown to migrate as a single band on native gels when each of their arms contains eight nucleotide pairs. However, they can be stabilized if their arms contain 16 nucleotide pairs. Ferguson analysis of these junctions in combination with three-arm and four-arm junctions indicates a linear increase in friction constant as the number of arms increases, with the four-arm junction migrating anomalously. The five-arm junction does not appear to have any unusual stacking structure, and all strands show similar responses to hydroxyl radical autofootprinting analysis. By contrast, one strand of the six-arm junction shows virtually no protection from hydroxyl radicals, suggesting that it is the helical strand of a preferred stacking domain. Both junctions are susceptible to digestion by T4 endonuclease VII, which resolves Holliday junctions. However, the putative helical strand of the six-arm junction shows markedly reduced cleavage, supporting the notion that its structure is largely found in a helical conformation. Branched DNA molecules can be assembled into structures whose helix axes form multiply connected objects and networks. The ability to construct five-arm and six-arm junctions vastly increases the number of structures and networks that can be built from branched DNA components. Icosahedral deltahedra and 11 networks with 432 symmetry, constructed from Platonic and Archimedean solids, are among the structures whose construction is feasible, now that these junctions can be made.

Base Sequence↗

PubMed2006

Effect of bilateral reaching on affected arm motor control in stroke--with and without loading on unaffected arm.

PURPOSE: To investigate the effect of bilateral reaching, with/without inertial loading on the unaffected arm, on hemiparetic arm motor control in stroke. METHODS: Twenty unilateral stroke patients were recruited. A three-dimensional optical motion capture system was used to measure the movement trajectory of the hemiparetic arm while performing three tasks: affected limb reaching forward; two-limb reaching forward; and two-limb reaching forward with inertia loading of 25% upper limb weight on the unaffected limb, respectively. Kinematical parameters were utilized to quantify the reaching performance of the affected arm. RESULTS: No matter whether loading was applied on the unaffected arm or not, the bilateral reaching task did not significantly facilitate smoother and faster movement. Furthermore, during bilateral reaching task with/without loading on the unaffected arm, stroke patients showed slower movement, lower maximal movement velocity, feedback control dominant and discontinuous movements in the affected arm than the same task with unilateral reaching. Subjects showed the greatest active upper extremity range of motion in proximal joints during the bilateral reaching task without unaffected arm loading. The amount of trunk movement also increased during bilateral reaching either with or without loading on the unaffected arm. Patients with moderate upper extremity motor impairment performed more discontinuous movements and less active elbow range of motion during bilateral reaching tasks; however, those with mild upper extremity motor impairment performed smoother movements and demonstrated greater active elbow range of motion during bilateral reaching tasks. CONCLUSIONS: Bilateral reaching tasks with/without loading on the unaffected arm could be considered as adding challenges during motor control training. Training with bilateral arm movements may be considered as a treatment strategy, and can be incorporated in stroke rehabilitation to facilitate greater arm active movement and improve motor control performance in the affected arm.

Adult↗

PubMed1995

Isolated effects of peripheral arm and central body cooling on arm performance.

BACKGROUND: Whole body cooling impairs manual arm performance. The independent contributions of local (peripheral) and/or whole body (central) cooling are not known. Therefore, a protocol was developed in which the arm and the rest of the body could be independently cooled. METHODS: Biceps temperature (Tmus), at a depth of 20 mm, and esophageal temperature (Tes) were measured. Six subjects were immersed to the clavicles in a tank (body tank) of water under 3 conditions: 1) cold body-cold arm (CB-CA); 2) warm body-cold arm (WB-CA); and 3) cold body-warm arm (CB-WA). In the latter two conditions, subjects placed their dominant arm in a separate (arm) tank. Water temperature (Tw) in each tank was independently controlled. In conditions requiring cold body and/or cold arm, Tw in the appropriate tanks was 8 degrees C. In conditions requiring warm body and/or warm arm, Tw in the appropriate tanks was adjusted between 29 and 38 degrees C to maintain body/arm temperature at baseline values. A battery of 6 tests, requiring fine or gross motor movements, were performed immediately before immersion and after 15, 45, and 70 minutes of immersion. RESULTS: In CB-CA, Tes decreased from an average of 37.2 to 35.6 degrees C and Tmus decreased from 34.6 to 22.0 degrees C. In WB-CA, Tmus decreased to 18.1 degrees C (Tes = 37.1 degrees C), and in CB-WA, Tes decreased to 35.8 degrees C (Tmus = 34.5 degrees C). By the end of immersion, there were significant decrements (43-85%) in the performance of all tests in CB-CA and WB-CA (p < 0.0002); scores for each test were similar in these two conditions. There was no significant change in scores throughout the CB-WA condition. In both conditions with arm cooling (i.e., WB-CA and CB-CA), Tmus accounted for 85-98% of the variance in all tests. When the core was cooled in the CB-WA condition, Tes was significantly correlated to scores in only two tests (accounted for 90 and 93% of the variance) although the actual effect was small. In the CB-CA condition, partial correlations indicated that Tes accounted for 4-10% of the variance in scores of 4 tests. CONCLUSIONS: We conclude that cooling of the body and/or the arm elicits large decrements in finger, hand and arm performance. The decrements are due almost entirely to the local effects of arm tissue cooling.

Adult↗

PubMed1999

Computer simulation of flagellar movement: VII. Conventional but functionally different cross-bridge models for inner and outer arm dyneins can explain the effects of outer arm dynein removal.

Outer arm dynein removal from flagella by genetic or chemical methods causes decreased frequency and power, but little change in bending pattern. These results suggest that outer arm dynein operates within bends to increase the speed of bend propagation, but does not produce forces that alter the bending pattern established by inner arm dyneins. A flagellar model incorporating different cross-bridge models for inner and outer arm dyneins has been examined. The inner arm dynein model has a hyperbolic force-velocity curve, with a maximum average force at 0 sliding velocity of about 14 pN for each 96 nm group of inner arm dyneins. The outer arm dynein model has a very different force-velocity curve, with a maximum force at about 10-15% of V(max). The outer arm dynein model is adjusted so that the unloaded sliding velocity for a realistic mixture of inner and outer arm dyneins is twice the unloaded sliding velocity for the inner arm dynein model alone. With these cross-bridge models, a flagellar model can be obtained that reduces its sliding velocity and frequency by approximately 50% when outer arm dyneins are removed, with little change in bending pattern. The addition of outer arm dyneins, therefore, gives an approximately 4-fold increase in power output against viscous resistances, and outer arm dyneins may generate 90% or more of the power output. Cell Motil.

Animals↗

PubMed2005

Spatial configuration and list learning of proximally cued arms by rats in the enclosed four-arm radial maze.

In an enclosed four-arm radial maze, after sampling three experimenter-selected baited arms (the study segment) and following rotation of the maze, rats had to find the fourth baited arm among all four unblocked arms (test segment). The rats learned this task with two sets of arm cues, objects at arms' entrances and full arm inserts, each maintained in a fixed configuration. When we changed the configuration of one set of arms to its mirror image and that of the other set to a more mixed variation by switching opposite and adjacent cued arms, the rats' accuracy was similarly disrupted (Experiment 1). In Experiment 2, the same rats rapidly recovered their high search accuracy on four new configurations recombined from pairs of adjacent arms and pairs of opposite cued arms from t he previous finaltwo configurations. Their test segment search accuracy, however, was again disrupted when these configurations were varied either only over trials' study segments or only over trials' test segments. In Experiment 3, however, these rats attained accuracy as high on two sets of cued arms with constantly changing configurations as on two sets with constant configurations. Thus, the rats were able to separately represent four different spatially stable configurations, and then they could learn to represent two of these configurations as lists of spatially irrelevant items. We discuss these findings in terms of association theory and parallel map theory (Jacobs & Schenk, 2003).

Animals↗

PubMed1997

Arm-movement-related neurons in the primate superior colliculus and underlying reticular formation: comparison of neuronal activity with EMGs of muscles of the shoulder, arm and trunk during reaching.

Neuronal activity was recorded from the superior colliculus (SC) and the underlying reticular formation in two monkeys during an arm reaching task. Of 744 neurons recorded, 389 (52%) clearly modulated their activity with arm movements. The temporal activity patterns of arm-movement-related neurons often had a time course similar to rectified electromyograms (EMGs) of particular muscles recorded from the shoulder, arm or trunk. These reach cells, as well as the muscles investigated, commonly exhibited mono- or biphasic (less frequently tri- or polyphasic) excitatory bursts of activity, which were related to the (pre-)movement period, the contact phase and/or the return movement. The vast majority of reach cells exhibited a consistent activity pattern from trial to trial as did most of the muscles of the shoulder, arm and trunk. Similarities between the activity patterns of the neurons and the muscles were sometimes very strong and were especially notable with the muscles of the shoulder girdle (e.g. trapezius descendens, supraspinatus, infraspinatus or the anterior and medial deltoids). This high degree of co-activation suggests a functional linkage, though not direct, between the collicular reach cells and these muscles. Neuronal activity onset was compared with that of 25 muscles of the arms, shoulders and trunk. The majority of cells (78.5%) started before movement onset with a mean lead time of 149+/-90 ms, and 36.5% were active even before the earliest EMG onset. The neurons exhibited the same high degree of correlation (r=0.97, Spearman rank) between activity onset and the beginning of the arm movement as did the muscles (r=0.98) involved in the task. The mean neuronal reach activity (background subtracted) ranged between 7 and 193 impulses/s (mean 40.5+/-24.2). The mean modulation index calculated [(reach activity background activity)/reach activity+background activity)] was 0.75+/-0.23 for neurons (n=358) and 0.87+/-0.14 for muscles (n=25). As the monkeys fixated the reach target constantly during an arm movement, neuronal activity which was modulated in this period was not related to eye movements. The three neck muscles investigated in the reach task exhibited no reach-related activity modulation comparable to that of either the reach cells or the muscles of the shoulder, arm and trunk. However, tonic neck muscle EMG was monotonically related to horizontal eye position. The clear skeletomotor discharge characteristics of arm-movement-related SC neurons revealed in this study agree with those already known from other sensorimotor regions (for example the primary motor, the premotor and parietal cortex, the basal ganglia or the cerebellum) and are consistent with the possible role of this population of reach cells in the control of arm movements.

Animals↗

PubMed1986

Linear growth measurement: a comparison of single arm-lengths and arm-span.

An investigation was done to determine whether the arm-lengths of 44 children with myelomeningocele differed from those of 96 control children; whether the level of the meningocele lesion has any effect on arm-length; and to compare the relationship between arm-length and both stature and age. Mean total arm-lengths did not differ significantly between the two groups of children. However, the mean arm-spans of children with high myelomeningocele lesions differed significantly from those of control children. Within the myelomeningocele group, the height of the lesion had no significant effect on any of the arm-length variables. Very high positive correlations were found between upper-arm and total arm-lengths and stature, and between arm-span and stature in the control children. These results suggest that arm-length may be used as an alternative measure of linear growth in children, and that a single arm-length will be the most accurate indicator of growth of children with myelomeningocele.

Arm↗