High-frequency submaximal stimulation over muscle evokes centrally generated forces in human upper limb skeletal muscles

Control of posture and movement requires control of the output from motoneurons. Motoneurons of human lower limb muscles exhibit sustained, submaximal activity to high-frequency electrical trains, which has been hypothesized to be partly triggered by monosynaptic Ia afferents. The possibility to trigger such behavior in upper limb motoneurons and the potential unique role of Ia afferents to trigger such behavior remain unclear. Subjects ( n = 9) received high-frequency trains of electrical stimuli over biceps brachii and flexor pollicis longus (FPL). We chose to study the FPL muscle because it has weak monosynaptic Ia afferent connectivity and it is involved in fine motor control of the thumb. Two types of stimulus trains (100-Hz bursts and triangular ramps) were tested at five intensities below painful levels. All subjects exhibited enhanced torque in biceps and FPL muscles after both types of high-frequency train. Torques also persisted after stimulation, particularly for the highest stimulus intensity. To separate the evoked torques that resulted from a peripheral mechanism (e.g., muscle potentiation) and that which resulted from a central origin, we studied FPL responses to high-frequency trains after complete combined nerve blocks of the median and radial nerves ( n = 2). During the blocks, high-frequency trains over the FPL did not yield torque enhancements or persisting torques. These results suggest that enhanced contractions of central origin can be elicited in motoneurons innervating the upper limb, despite weak monosynaptic Ia connections for FPL. Their presence in a recently evolved human muscle (FPL) indicates that these enhanced contractions may have a broad role in controlling tonic postural outputs of hand muscles and that they may be available even for fine motor activities involving the thumb.

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Cortical Control of Human Motoneuron Firing During Isometric Contraction

Journal of Neurophysiology ◽

10.1152/jn.1997.77.6.3401 ◽

1997 ◽

Vol 77 (6) ◽

pp. 3401-3405 ◽

Cited By ~ 372

Author(s):

Stephan Salenius ◽

Karin Portin ◽

Matti Kajola ◽

Riitta Salmelin ◽

Riitta Hari

Keyword(s):

Motor Cortex ◽

Upper Limb ◽

Isometric Contraction ◽

Lower Limb ◽

Biceps Brachii ◽

Cortical Control ◽

Lower Limb Muscles ◽

Cortical Rhythms ◽

Motor Unit Firing ◽

Limb Muscles

Salenius, Stephan, Karin Portin, Matti Kajola, Riitta Salmelin, and Riitta Hari. Cortical control of human motoneuron firing during isometric contraction. J. Neurophysiol. 77: 3401–3405, 1997. We recorded whole scalp magnetoencephalographic (MEG) signals simultaneously with the surface electromyogram from upper and lower limb muscles of six healthy right-handed adults during voluntary isometric contraction. The 15- to 33-Hz MEG signals, originating from the anterior bank of the central sulcus, i.e., the primary motor cortex, were coherent with motor unit firing in all subjects and for all muscles. The coherent cortical rhythms originated in the hand motor area for upper limb muscles (1st dorsal interosseus, extensor indicis proprius, and biceps brachii) and close to the foot area for lower limb muscles (flexor hallucis brevis). The sites of origin corresponding to different upper limb muscles did not differ significantly. The cortical signals preceded motor unit firing by 12–53 ms. The lags were shortest for the biceps brachii and increased systematically with increasing corticomuscular distance. We suggest that the motor cortex drives the spinal motoneuronal pool during sustained contractions, with the observed cortical rhythmic activity influencing the timing of efferent commands. The cortical rhythms could be related to motor binding, but the rhythmic output may also serve to optimize motor cortex output during isometric contractions.

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Upper limb proprioception and fine motor function in young pianists

Human Movement Science ◽

10.1016/j.humov.2020.102748 ◽

2021 ◽

Vol 75 ◽

pp. 102748

Author(s):

Yu-Ting Tseng ◽

Fu-Chen Chen ◽

Chia-Liang Tsai ◽

Jürgen Konczak

Keyword(s):

Motor Function ◽

Upper Limb ◽

Fine Motor ◽

Fine Motor Function ◽

Limb Proprioception

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NECROTISING SOFT TISSUE INFECTION OF BILATERAL UPPER LIMB CAUSED BY THE INJECTION OF ORAL BACTERIA: A CASE REPORT

Hand Surgery ◽

10.1142/s021881041372012x ◽

2013 ◽

Vol 18 (02) ◽

pp. 243-246 ◽

Cited By ~ 1

Author(s):

Yuichi Yoshii ◽

Tomoo Ishii ◽

Shinsuke Sakai

Keyword(s):

Soft Tissue ◽

Upper Limb ◽

Soft Tissue Infection ◽

Soft Tissues ◽

Biceps Brachii ◽

Subcutaneous Tissue ◽

Oral Bacteria ◽

Tissue Infection ◽

Left Elbow ◽

The Right

Necrotising soft tissue infection is a rare and rapid process with devastating consequence. We report one case of necrotising soft tissue infection in a bilateral upper limb with uncommon oral bacteria. Radiological imaging revealed the presence of gas in upper limb soft tissues, and an MRI showed the localised signal changes in the biceps muscle of the right upper arm, and the subcutaneous tissue of the left elbow. The patient was treated with surgical resection of the infected muscle and wide debridement of the subcutaneous tissue. Antibiotics were initiated. The patient recovered immediately without functional deficit. The unique features of this patient were possible to observe in the progression of the necrotising soft tissue infection in the bilateral upper limb with intentional injection of oral bacteria, and the effect of biceps brachii resection in a prime age worker.

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Validity of Skeletal Muscle Ultrasound in Assessment of Suspected Limb Girdle Muscular Dystrophy Patients

QJM ◽

10.1093/qjmed/hcab102.023 ◽

2021 ◽

Vol 114 (Supplement_1) ◽

Author(s):

Rasha M Ibrahim ◽

Haitham M Hamdy ◽

Amr A Mohammed ◽

Ahmed M Elsadek ◽

Ahmed M Bassiouny ◽

...

Keyword(s):

Muscular Dystrophy ◽

Upper Limb ◽

Lower Limb ◽

Limb Girdle Muscular Dystrophy ◽

Ultrasound Images ◽

General Electric ◽

Cross Sectional ◽

Lower Limb Muscles ◽

Limb Muscles ◽

Muscle Ultrasound

Abstract Background Limb-girdle muscular dystrophies (LGMDs) are a clinically and genetically heterogeneous group of disorders characterized by progressive muscle weakness and degenerative muscle changes. Studies have shown that ultrasound can be useful both for diagnosis and follow-up of LGMDs patients. Objectives This study aims to measure the sensitivity and the specificity of muscle ultrasound in assessment of suspected limb girdle muscular dystrophy patients. Subjects and Methods This cross-sectional descriptive study was conducted on Fifty-five patients with suspected LGMD from neuromuscular unit, myology clinic, Ain Shams University hospitals and eight healthy subjects. Age was above 2 years. Both sexes were included in the study. They underwent real-time B-mode ultrasonography performed with using Logiq p9 General Electric ultrasound machine and General Electric 7-11.5 MHZ linear array ultrasound probe. All ultrasound images have been obtained and scored by a single examiner and muscle echo intensity was visually graded semiquantitative according to Heckmatt's scale. The examiner was blinded to the muscle biopsy results and clinical evaluations. Results Statistical analysis revealed that the diagnostic performance of muscle US (Heckmatt’s score) in LGMD is most sensitive when calculated in all examined upper limb and lower limb muscles, followed by lower limb muscles alone. US of upper limb was found to be the least sensitive. Conclusions Muscle ultrasound is a practical and reproducible and valid tool that can be used in assessment of suspected LGMD patients.

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Shingles Following Axillary Nerve Block a Case Report

Journal of Hand Surgery (European Volume) ◽

10.1016/0266-7681_86_90030-6 ◽

1986 ◽

Vol 11 (1) ◽

pp. 115-116

Author(s):

N. J. PERCIVAL

Keyword(s):

Case Report ◽

Herpes Zoster ◽

Nerve Block ◽

Upper Limb ◽

Axillary Nerve ◽

Nerve Blocks ◽

Upper Limb Surgery ◽

Axillary Nerve Block

Axillary nerve blocks are now frequently used for emergency and elective upper limb surgery. The method gives reliable anaesthesia with few complications. A case is described in which a patient developed Herpes Zoster following an Axillary Nerve Block, a hitherto unreported complication.

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Hand function and fine motor activities

Finnie's Handling the Young Child with Cerebral Palsy at Home ◽

10.1016/b978-0-7506-8810-9.00019-8 ◽

2009 ◽

pp. 243-268

Author(s):

Dido Green

Keyword(s):

Hand Function ◽

Fine Motor ◽

Motor Activities

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Selectivity and excitability of upper-limb muscle activation during cervical transcutaneous spinal cord stimulation in humans

Journal of Applied Physiology ◽

10.1152/japplphysiol.00132.2021 ◽

2021 ◽

Author(s):

Roberto M. de Freitas ◽

Atsushi Sasaki ◽

Dimitry G. Sayenko ◽

Yohei Masugi ◽

Taishin Nomura ◽

...

Keyword(s):

Spinal Cord ◽

Upper Limb ◽

Spinal Cord Stimulation ◽

Muscle Activation ◽

Anterior Neck ◽

Hand Muscles ◽

Ia Afferents ◽

Arm Muscles ◽

Muscle Responses ◽

Transcutaneous Spinal Cord Stimulation

Cervical transcutaneous spinal cord stimulation (tSCS) efficacy for rehabilitation of upper-limb motor function was suggested to depend on recruitment of Ia afferents. However, selectivity and excitability of motor activation with different electrode configurations remains unclear. In this study, activation of upper-limb motor pools was examined with different cathode and anode configurations during cervical tSCS in 10 able-bodied individuals. Muscle responses were measured from six upper-limb muscles simultaneously. First, post-activation depression was confirmed with tSCS paired pulses (50 ms interval) for each cathode configuration (C6, C7, and T1 vertebral levels), with anode on the anterior neck. Selectivity and excitability of activation of the upper-limb motor pools were examined by comparing the recruitment curves (10-100 mA) of first evoked responses across muscles and cathode configurations. Our results showed that hand muscles were preferentially activated when the cathode was placed over T1 compared to the other vertebral levels, while there was no selectivity for proximal arm muscles. Furthermore, higher stimulation intensities were required to activate distal hand muscles than proximal arm muscles, suggesting different excitability thresholds between muscles. In a separate protocol, responses were compared between anode configurations (anterior neck, shoulders, iliac crests, and back), with one selected cathode configuration. The level of discomfort was also assessed. Largest muscle responses were elicited with the anode configuration over the anterior neck, while there were no differences in the discomfort. Our results therefore inform methodological considerations for electrode configuration to help optimize recruitment of Ia afferents during cervical tSCS.

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Effects of Focal Vibration over Upper Limb Muscles on the Activation of Sensorimotor Cortex Network: An EEG Study

Journal of Healthcare Engineering ◽

10.1155/2019/9167028 ◽

2019 ◽

Vol 2019 ◽

pp. 1-7 ◽

Cited By ~ 1

Author(s):

Wei Li ◽

Chong Li ◽

Quan Xu ◽

Linhong Ji

Keyword(s):

Upper Limb ◽

Sensorimotor Cortex ◽

Biceps Brachii ◽

Central Area ◽

Therapeutic Effects ◽

Relative Power ◽

Alpha Band ◽

Beta Band ◽

Muscle Belly ◽

Limb Muscles

Studying the therapeutic effects of focal vibration (FV) in neurorehabilitation is the focus of current research. However, it is still not fully understood how FV on upper limb muscles affects the sensorimotor cortex in healthy subjects. To explore this problem, this experiment was designed and conducted, in which FV was applied to the muscle belly of biceps brachii in the left arm. During the experiment, electroencephalography (EEG) was recorded in the following three phases: before FV, during FV, and two minutes after FV. During FV, a significant lower relative power at C3 and C4 electrodes and a significant higher connection strength between five channel pairs (Cz-FC1, Cz-C3, Cz-CP6, C4-FC6, and FC6-CP2) in the alpha band were observed compared to those before FV. After FV, the relative power at C4 in the beta band showed a significant increase compared to its value before FV. The changes of the relative power at C4 in the alpha band had a negative correlation with the relative power of the beta band during FV and with that after FV. The results showed that FV on upper limb muscles could activate the bilateral primary somatosensory cortex and strengthen functional connectivity of the ipsilateral central area (FC1, C3, and Cz) and contralateral central area (CP2, Cz, C4, FC6, and CP6). These results contribute to understanding the effect of FV over upper limb muscles on the brain cortical network.

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