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1.
Joe Iwanaga Jason Refsland Lee Iovino Gary Holley Tyler Laws Rod J. Oskouian R. Shane Tubbs 《Clinical anatomy (New York, N.Y.)》2017,30(6):733-735
The extraocular muscles consist of the superior, inferior, lateral, and medial rectus muscles and the superior and inferior oblique muscles. This study aimed to create a new teaching model for demonstrating the function of the extraocular muscles. A coronal section of the head was prepared and sutures attached to the levator palpebral superioris muscle and six extraocular muscles. Tension was placed on each muscle from a posterior approach and movement of the eye documented from an anterior view. All movements were clearly seen less than that of the inferior rectus muscle. To our knowledge, this is the first cadaveric teaching model for demonstrating the movements of the extraocular muscles. Clin. Anat. 30:733–735, 2017. © 2017Wiley Periodicals, Inc. 相似文献
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Brinkworth RS Türker KS 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2005,164(2):165-176
The changes in the minimum time to consciously react (reaction time) and the order of jaw muscle recruitment to precisely controlled axial stimulation of the incisors during controlled jaw movements are not known. To this end, ten subjects were recruited to investigate the reaction time of bilateral temporalis and masseter muscles and bite force. Stimuli were delivered axially to the upper central incisors during active jaw closing and opening, and under static conditions. The results showed that the reaction time was increased an average of 35% during both jaw opening and closing movements when compared with static jaw conditions. The left temporalis was recruited approximately 10 ms before the right temporalis, whereas no significant side differences were found between the masseter muscles. The masseter muscles were recruited an average of 20 ms before the temporalis muscles during jaw closing, but no difference existed during opening. Under static conditions the reaction time in the bite force was approximately 16 ms longer than the left temporalis, but was not significantly different from the reaction time of any of the other muscles, indicating that, under the static conditions tested, the left temporalis was more often responsible for initiation of the mechanical reactions in the jaw. Because of active compensation, no force measurements were made during jaw movement. This study is a prerequisite for investigations into the modulation of reflexes during jaw movement, because a response to a stimulus commencing after the minimum reaction time may not be entirely reflex in origin. 相似文献
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The movement of muscle precursor cells between adjacent regenerating muscles in the mouse 总被引:4,自引:0,他引:4
Summary Regeneration of mature skeletal muscle fibers involves the formation of new multinucleate muscle fibres by the fusion together of mononucleate muscle precursor cells. Such precursor cells appear to be largely or entirely derived from satellite cells, located between the basement membrane and the sarcolemma of the muscle fibre. We have previously presented evidence that precursor cells which contribute to regenerating muscle in a region of muscle damage are not all locally derived but that some migrate in from exogenous sources. The present study examines the possibility that a regenerating muscle might receive muscle precursor cells from neighbouring muscles. To do this we have made whole muscle allografts in the mouse and used the two murine isoenzyme allotypes of the dimeric enzyme Glucose-6-Phosphate Isomerase (GPI) as markers to demonstrate whether there is movement of muscle precursor cells between these allografts and adjacent host muscles. In host muscles adjacent to some allografts, a hybrid form of GPI was detected, each molecule consiting of one donor and one host GPI subunit. Such heterodimers can form only where host and donor nuclei share a common cytoplasm: in muscles this means that mosaic host/donor muscle fibres are present. The presence of such fibres implies that muscle precursor cells must have migrated into the host muscle from the neighbouring allograft. 相似文献
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This study aimed to clarify how the activities of trunk and lower limb muscles during a landing-to-jump (L-J) movement are coordinated to perform the task effectively. Electromyography (EMG) activities of trunk and lower limb muscles as well as kinematic and ground reaction force data were recorded while 17 subjects performed 5 L-Js from a height of 35 cm. The L-J was divided into four phases: PRE phase, 100 ms preceding ground contact; ABSORPTION phase, from ground contact through 100 ms; BRAKING phase, from the end of the ABSORPTION phase to the time of the lowest center of mass position; and PROPULSION phase, from the end of the BRAKING phase to takeoff. The trunk extensor and flexors showed reciprocal activation patterns through the L-J. In the PROPULSION phase, the timings when the EMG activities of the extensor muscles peaked were characterized as a sequential proximal-to-distal pattern. Furthermore, the peak vertical ground reaction force in the ABSORPTION phase relative to body mass negatively correlated to the jump height of the L-J movement and positively correlated with the magnitude of the EMG activities of the soleus in the PRE phase and those of the soleus and rectus abdominis in the ABSORPTION phase. These findings indicate that the intensities and peak timings of muscle activities in the trunk and lower limb are coordinated during the L-J movement and, the coordinated activities would play functional roles such as impact absorption, braking against the descent of body and force generation and direction control for jumping. 相似文献
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On the content of myoglobin in human muscles 总被引:1,自引:0,他引:1
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Huffenus AF Amarantini D Forestier N 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2006,170(4):438-447
To investigate the strategies developed by the central nervous system to compensate for fatigue in muscles, we studied the
changes in the relative mechanical contribution of the joint torques in a multi-joint movement following an isometric exhaustion
test. Eighteen male subjects performed throws, moving the arm in the horizontal plane, before and after two fatigue protocols.
Muscular fatigue was induced either in the distal (extensor digitorum communis) or in the proximal (triceps brachii) agonist
muscle of the arm. The kinematic, kinetic and electromyographic parameters of the movement were analysed. The subjects produced
two different coordinations following the fatigue protocols. In the distal fatigue condition, the wrist angular velocity was
maintained by decreasing elbow active torque. In the proximal fatigue condition, the compensatory strategy involved increasing
the contribution of the wrist. In fact, the control of elbow and wrist was modified in order to compensate for the different
mechanical effects. 相似文献
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M B Dutia 《Progress in neurobiology》1991,37(2):165-178
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Jacques Duchateau Serge Le Bozec Karl Hainaut 《European journal of applied physiology》1986,55(5):476-481
Summary The relative contribution of synergistic muscles has been studied during pedalling on a bicycle. The electromyographic (EMG)
activity of the different components of triceps surae (namely soleus or SOL and medial gastrocnemius or MG) has been recorded
and analyzed for increasing pedalling speed performed against increasing resistance. The results indicate that SOL IEMG (integrated
EMG) increases linearly (y=2x−12.1; r=0.98) with increasing load (10–70 N) at constant speed (60 rpm), whereas no change is noted in MG IEMG below 40 N. In contrast,
wehen the pedalling speed is increased (from 30 to 170 rpm) at constant load, MG IEMG shows the largest increase. Furthermore,
although in both muscles EMG activity appears earlier in the movement with increases in load and/or speed, the delay between
the onset of both EMGs remains unchanged at constant speed and synchronization of MG with SOL is only observed when speed
is increased above 140 rpm. These results suggest that the different muscles of the triceps surae make specific contributions
to the development of the mechanical tension required to maintain or increase the speed of movement.
This work was supported by the Fonds National de la Recherche Scientifique of Belgium and the Conseil de la Recherche of the
University of Brussels 相似文献
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On the content of cytochrome C in human muscles 总被引:1,自引:0,他引:1
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Kassavetis P Hoffland BS Saifee TA Bhatia KP van de Warrenburg BP Rothwell JC Edwards MJ 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2011,209(3):437-442
Highly selective activation of the desired muscles for each movement and inhibition of adjacent muscles is attributed to surround
inhibition (SI) which differentially modulates corticospinal excitability in active and surrounding muscles. Cerebellar brain
inhibition (CBI) is another inhibitory neuronal network which is known to be active at rest and during tonic muscle contraction.
The way in which CBI may be modulated at movement onset and its relationship with SI has not previously been investigated.
We assessed motor evoked potential (MEP) size and CBI in first dorsal interosseus (FDI) and abductor digiti minimi (ADM) muscles
at rest and during a simple motor task where FDI was an active muscle and ADM was not involved in the movement (surround muscle).
At onset of movement, MEP size in ADM was significantly suppressed, confirming the existence of SI. In contrast, CBI in both
muscles was found to be significantly decreased at the onset of the movement. This was confirmed even after adjustments for
changes in MEP size occurring due to onset of muscle activity in FDI and the effects of SI in ADM. Our findings fail to functionally
link SI with CBI, but they do indicate a non-topographically specific modulation of CBI in association with initiation of
voluntary movement. 相似文献
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J. T. Dennerlein C. D. Mote Jr. D. M. Rempel 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1998,121(1):1-6
A single keystroke during touch-typing is a rapid, goal-directed motion of the fingertip which consists of two single-direction
movements. The neural control and the role of the finger extrinsic musculature during typing have not yet been explained.
The fingertip motion and force, and the intramuscular electromyographic (EMG) activity (fine-wire) of the index finger extrinsic
musculature were measured during touch-typing by ten experienced typists. The motions and forces were repeatable qualitatively
across keystrokes. A three-burst EMG pattern was observed during a single keystroke. The three bursts were: (1) a burst of
extensor activity lifted the finger before the keystroke; (2) a burst of flexor activity followed while the fingertip was
moving downward; and (3) a second burst of extensor activity occurred as the fingertip reached the end of key travel. The
timing of the third burst suggests the role of the extensors is to remove the fingertip from the keyswitch rather than stop
the downward motion of the finger. The collision with the end of key travel stops the downward finger motion. The timing of
the finger flexor EMG activity, burst 2, suggests that the flexor contraction principally overcomes the activation force of
the keyswitch rather than accelerates the finger downward as expected.
Received: 1 April 1997 / Accepted: 29 December 1997 相似文献
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A. A. M. Tax J. J. Denier van der Gon C. J. Erkelens 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》1990,81(3):567-572
Summary Motor-unit activity in m. biceps brachii, m. brachialis and m. brachioradialis during isometric contractions has been compared
with motor-unit activity during slow voluntary (extension and flexion) movements made against external loads. During these
slow movements the recruitment threshold of m. biceps motor units is considerably lower than it is during isometric contractions
but the recruitment threshold of both m. brachialis and m. brachioradialis motor units is considerably higher. For all three
elbow flexor muscles the motor-unit firing frequency seems to depend on the direction of movement: the firing frequency is
higher during flexion movements (3 deg/s) and lower during extension movements (−3 deg/s) than during isometric contractions.
The relative contribution of the biceps to the total exerted flexion torque during slow voluntary movements is estimated to
increase from 36% to about 48% and that of the brachialis/brachioradialis is estimated to decrease from 57% to about 45% compared
to the relative contribution of these muscles during isometric contractions. This difference in the relative contribution
of the three major elbow flexor muscles is shown to be caused by differences in the central activation in force tasks and
movement tasks. 相似文献
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Muscle co-contraction is important in stabilizing the spine. The effects of movement speed and direction on the cervical co-contraction were, however, not yet investigated. Surface electromyographies of three paired cervical muscles were measured in 17 young healthy subjects. The subjects performed voluntary neck movements in sagittal and coronal plane at fast, medium, and slow speeds. The co-contraction ratio was defined as the normalized integration of antagonistic electromyographic activities divided by that of total muscle activities. The results showed that the co-contraction ratio at fast speed (0.42 +/- 0.21) was smaller than that at medium (0.45 +/- 0.20) and slow (0.46 +/- 0.19) speeds (P = 0.001). The co-contraction ratio was different between flexion and extension, but was similar between left and right lateral bending. The implications of co-contraction patterns include: (1) agonistic activities increase with speed but antagonistic activities do not increase accordingly; (2) neck extensors are highly activated during sagittal motions; and (3) muscular activations are symmetric during coronal motions. In conclusion, the co-contraction patterns from young healthy subjects demonstrate normal neuromuscular control in regulating the stiffness of cervical spine, and may further be references to assess the neck disorders in elderly or patients. 相似文献
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Using the KinCom 500H isokinetic dynamometer the first part of this study measured the characteristics of the force velocity relationship curve for the human knee extensors between ?1.57 (eccentric) and 3.67?(concentric)?rads?·?s?1 (?90 and 210°?s1) for both legs in 4 subjects. A significant increase in force generation was seen in eccentric activity at 0.52?rads?·?s?1 (30°?s?1) but not at 1.57?rads?·?s?1 (90°?s?1) compared to maximum voluntary isometric force (P?0.005). This increase was, however, lower than would be expected from the classical force-velocity relationship. The second part of the study examined whether restricting the range of movement was able to further increase the eccentric forces. In a further 6 subjects, the eccentric contractions were repeated during either an 80° (15–95° flexion) and a 50° (45–95° flexion) range of movement. Significant increases in force were seen over the shorter range of movement at 0.52?rads?·?s?1 (30°?s?1) (P?=?0.006) and 1.57?rads?·?s?1 (90°?s?1) (P?0.001). 相似文献