Brachioradialis Research Articles

Does Action Observation of the Whole Task Influence Mirror Neuron System and Upper Limb Muscle Activity Better Than Part Task in People With Stroke?

Background: Task-based action observation and imitation (AOI) is a promising intervention to enhance upper limb (UL) motor function poststroke. However, whether whole/part task must be trained in the AOI therapy needs further substantiation. Objective: The objective of this study is to assess and compare the mirror neuron activity and UL muscle activity during AOI of reaching task in terms of whole task (complete movement) and part task (proximal arm movements and distal arm movements). Methods: In this cross-sectional study, 26 participants with first-time unilateral stroke were asked to observe the prerecorded videos of a reaching task in terms of a whole task and proximal and distal components, followed by imitation of the task, respectively. Electroencephalographic (EEG) mu rhythm suppression and electromyographic amplitude of six UL muscles were measured during the task. Results: The analysis of EEG revealed a statistically significant mu suppression score, indicating mirror neuron system activity, during AOI of the whole task in C3 (p = <0.001) and C4 (p = <0.001) electrodes compared to the part task. Percentage maximum voluntary contraction amplitudes of the deltoid (p = 0.002), supraspinatus (p = <0.001), triceps brachii (p = 0.002), brachioradialis (p = 0.006), and extensor carpi radialis (p = <0.001) muscles showed a significant increase in muscle activity during AOI of the whole task. Also, there seems to be a task observation-specific activation of muscles following AOI of proximal or distal tasks. Conclusion: The practice of the whole task should be given emphasis while framing the AOI treatment module to enhance reaching in people with stroke. Trial registration: Clinical Trials Registry-India (CTRI) identifier: CTRI/2018/04/013466.

A case of a rare hibernoma tumour and a brief literature review

Hibernomas refer to benign tumours of immature adipose tissue known a brown fat. They are most commonly found in areas where brown adipose tissue is still present in adulthood such as the shoulder, back, neck, best, arm and abdomen. This case study describes a 60 year old male who presented with a growing 15 mm lump in the right forearm. On examination, tenderness in the area surrounding the mass was elicited. A magnetic resonance image of the right forearm was performed which reported a large intramuscular lipomatous tumour within the brachioradialis muscle, in close relation to the neuromuscular bundle. Surgical excision was performed successfully. Histology was consistent with a diagnosis of a hibernoma tumour. The patient healed well with no evidence of infection or recurrence on follow up.

A Fresh Cadaver Study on the Innervation of Brachioradialis and Extensor Carpi Radialis Longus Muscles

Distal nerve transfers have revolutionized peripheral nerve surgery by allowing the transfer of healthy motor nerves to paralyzed ones without causing additional morbidity. Radial nerve branches to the brachialis (Ba), brachioradialis (Br), and extensor carpi radialis longus (ECRL) muscles have not been investigated in fresh cadavers. The radial nerve and its branches were dissected in 34 upper limbs from 17 fresh cadavers. Measurements were taken to determine the number, origin, length, and diameter of the branches. Myelinated fiber counts were obtained through histological analysis. The first branch of the radial nerve at the elbow was to the Ba muscle, followed by the branches to the Br and ECRL muscles. The Ba and Br muscles consistently received single innervation. The ECRL muscle showed varying innervation patterns, with one, two, or three branches. The branches to the Br muscles originated from the anterior side of the radial nerve, whereas the branches to the Ba and ECRL muscles originated from the posterior side. The average myelinated fiber counts favored the nerve to Br muscle over that to the ECRL muscle, with counts of 542 versus 350 and 568 versus 302 observed in hematoxylin and eosin and neurofilament staining, respectively. This study provides detailed anatomical insights into the motor branches of the radial nerve to the Ba, Br, and ECRL muscles. Understanding the anatomy of the radial nerve branches at the elbow is of utmost importance when devising a reconstructive strategy for upper limb paralysis. These findings can guide surgeons in selecting appropriate donor or recipient nerves for nerve transfer in cases of high tetraplegia and lower-type brachial plexus injuries.

Clinical anatomy of the lateral antebrachial cutaneous nerve: Is there any safe zone for interventional approach?

IntroductionThe lateral antebrachial cutaneous nerve (LACN) is a somatosensory nerve coursing in the lateral portion of the forearm. The nerve is located in a close proximity to the cephalic vein (CV) all along its course with a danger of being injured during venipuncture. The LACN also overlaps and communicates with the superficial branch of the radial nerve (SBRN) in the distal forearm and hand, making the awareness of their relationship of great importance in the treatment of neuroma. The aim of the study was to observe the relationship of the LACN to surrounding structures as well as its branching pattern and distribution. Materials and methodsNinety-three cadaveric forearms embalmed in formaldehyde were dissected. The relationship of the LACN to surrounding structures was noted and photographed, and distances between the structures were measured with a digital caliper. The cross-sectional relationships of the LACN and SBRN to the CV were described using heatmaps. ResultsThe emerging point of the LACN was found distally, proximally or at the level of the interepicondylar line (IEL). The LACN branched in 76 cases (81.7 %) into an anterior and posterior branch at mean distance of 47.8 ± 34.2 mm distal to the IEL. The sensory distribution was described according to the relationship of the LACN branches to the medial border of the brachioradialis muscle. The LACN supplying the dorsum of the hand was observed in 39.8 % of cases. The LACN and the SBRN intersected in 86 % of upper limbs with communications noticed in 71 % of forearms. The LACN was stated as the most frequent donor of the communicating branch resulting in neuroma located distal to the communication and being fed from the LACN. The relationship of the LACN and the CV showed that the IEL is the most appropriate place for the venipuncture due to maximal calibers of the CV and deep position of the LACN. The LACN was adjacent to the cubital perforating vein and the radial artery in all cases. The medial border of the brachioradialis muscle was observed less than 1.8 mm from the LACN. ConclusionThe study provides morphological data on the LACN distribution, branching pattern and relationship to surrounding structures in a context of clinical use in different spheres of medicine. The branching pattern of the LACN appears to be more constant compared to data provided by previous authors. We emphasized the meaning of cross-sectional relationship of the LACN to the CV to avoid venipuncture outside the cubital fossa if possible. The posterior branch of the LACN was predicted as appropriate donor of the graft for a digital nerve. The LACN appeared to be in a close proximity within the whole length of the brachioradialis muscle what the orthopedic surgeons must be concerned of. The meaning of the donor-nerve of the communicating branch in neuroma treatment was also introduced.

Large intramuscular and parosteal lipoma of the upper limb: A case report and literature review

Although lipomas are the most common benign soft-tissue tumors, the intramuscular type is rare and the parosteal type is even rarer. These types of tumors can present like malignant tumors like liposarcoma. Unlike superficial lipomas, deep lipomas (intramuscular/parosteal) require magnetic resonance imaging to evaluate for and rule out malignant features. We report this patient with giant and mixed types of rarest lipomas (intramuscular and parosteal) that arise from the humeral periosteum and within the brachioradialis muscle with encasement of the radial nerve. We aimed to increase awareness to think outside the box and shed light on this giant, rarest mixed type of intramuscular and parosteal lipomas. Furthermore, it emphasizes the need for careful investigations to rule out malignant tumors like liposarcoma. Finally, many orthopedic oncology centers designate large, deep lipomas as low-grade liposarcoma due to the risk of local recurrence.

Experimental Analysis of the Efficiency and Usability of Tylke Versus Magill Forceps.

The procedure of nasotracheal intubation (NI) has long been performed utilizing the Magill forceps as developed by Sir Ivan Magill in the 1920s. While used for nearly a century, several serious patient safety concerns remain including torn tube cuffs, vocal cord trauma, and inefficient tube placement. The Tylke forceps have been developed as a modification to the largely unchanged form of Magill forceps. In the present investigationwe compared the efficacy, number of clasps, and muscle activation involved in NI using the Tylke forceps versus the Magill forceps in previously untrained individuals. Tylke forceps showed faster successful NI over the standard Magill forceps at an average intubation time of 6.54s vs. 13.73s, respectively. Tylke forceps also had fewer clasps per intubation over the Magill. The trapezius, deltoid, and brachioradialis muscle activation was also compared in Tylke vs Magill forceps intubation trials. Tylke forceps required less lower muscle activation in the brachioradialis and trapezius over the Magill forceps with Tylke forceps resulting in higher deltoid muscle activation. Tylke forceps were more efficacious and reduced the number of clasps over the Magill forceps when used in successful NI with different muscle activation patterns.

Assessment of forearm muscles with ultrasound shear wave elastography in patients with acromegaly.

The effects of acromegaly on soft tissues, bones and joints are well-documented, but information on its effects on muscle mass and quality remains limited. The primary goal of this study is to assess the sonoelastographic features of forearm muscles in patients with acromegaly. Forty-five patients with acromegaly and 45 healthy controls similar in terms of gender, age, and body mass index (BMI) were included in a single-center, multidisciplinary, cross-sectional study. The body composition was analyzed using bioelectrical impedance analysis (BIA), and height-adjusted appendicular skeletal muscle index (hSMI) was calculated. The dominant hand's grip strength was also measured. Two radiologists specialized in the musculoskeletal system employed ultrasound shear wave elastography (SWE) to assess the thickness and stiffness of brachioradialis and biceps brachii muscles. The acromegaly group had significantly higher thickness of both the biceps brachii (p = 0.034) and brachioradialis muscle (p = 0.046) than the control group. However, the stiffness of the biceps brachii (p = 0.001) and brachioradialis muscle (p = 0.001) was lower in the acromegaly group than in the control group. Disease activity has not caused a significant difference in muscle thickness and stiffness in the acromegaly group (p > 0.05). The acromegaly group had a higher hSMI (p = 0.004) than the control group. The hand grip strength was similar between the acromegaly and control group (p = 0.594). The patients with acromegaly have an increased muscle thickness but decreased muscle stiffness in the forearm muscles responsible for elbow flexion. Acromegaly can lead to a permanent deterioration of the muscular structure regardless of the disease activity.

Load sharing between synergistic muscles characterized by a ligand-binding approach and elastography

The skeletal muscle contraction is determined by cross-bridge formation between the myosin heads and the actin active sites. When the muscle contracts, it shortens, increasing its longitudinal shear elastic modulus ({mu }_{L}). Structurally, skeletal muscle can be considered analogous to the molecular receptors that form receptor–ligand complexes and exhibit specific ligand-binding dynamics. In this context, this work aims to apply elastography and the ligand-binding framework to approach the possible intrinsic mechanisms behind muscle synergism. Based on the short-range stiffness principle and the acoustic–elasticity theory, we define the coefficient C, which is directly related to the fraction saturation of molecular receptors and links the relative longitudinal deformation of the muscle to its {mu }_{L}. We show that such a coefficient can be obtained directly from {mu }_{L} estimates, thus calculating it for the biceps brachii, brachioradialis, and brachialis muscles during isometric elbow flexion torque (τ) ramps. The resulting Cleft(tau right) curves were analyzed by conventional characterization methods of receptor–ligand systems to study the dynamical behavior of each muscle. The results showed that, depending on muscle, Cleft(tau right) exhibits typical ligand-binding dynamics during joint torque production. Therefore, the above indicates that these different behaviors describe the longitudinal shortening pattern of each muscle during load sharing. As a plausible interpretation, we suggested that this could be related to the binding kinetics of the cross-bridges during their synergistic action as torque increases. Likewise, it shows that elastography could be useful to assess contractile processes at different scales related to the change in the mechanical properties of skeletal muscle.

A case report on multiple accessory muscles and nerve variations in upper limb

During routine dissection of formalin fixed cadavers, the brachial plexus and other upper limb structures were observed for variations. In 65-year-old male cadaver, bilateral upper limb neuromuscular variations were identified. On the left side, median nerve had three roots (one medial and two lateral) and biceps brachii had an additional head which was originating from the mid shaft of humerus and joined with the main muscle at the lower third of arm, and was innervated by musculocutaneous nerve. On the right side, the brachioradialis muscle had an accessory head which took origin from the lateral side of humerus near deltoid tuberosity and joined with main tendon in the lower part of the forearm, and was innervated by radial nerve. The association of nerve variations and accessory muscles is clinically significant. As accessory muscle may lead to nerve or artery entrapment in the limb and is likely to cause palsy or ischemia, knowledge about the neuromuscular variations is clinically significant.

Transient Electromyographic Responses by Isokinetic Torque Release during Mechanically Assisted Elbow Flexion.

Power assistance on joint torque may not be beneficial to all the related muscles. We investigated the effects of power assistance on torque release during isokinetic elbow flexion. An isokinetic dynamometer system was used to simulate dynamic elbow flexion with power assistance, which altered the exercise conditions of baseline isometric torque (greater and lower) and rotation speed (faster and slower) of the lever arm. Ten male right-handed participants performed exercise tasks using the system. We measured (1) the electromyogram (EMG) amplitudes of the biceps brachii (BB), brachioradialis (BR), and triceps brachii (TB) muscles, (2) torque output and its variability, and (3) the perceived assistance level. Transient responses of the objective measurements were analyzed by observing three time epochs before and after power assistance. Greater variability and lower perceived assistance levels were observed when greater torque was released at a faster rotation speed. The torque output and EMG amplitudes of BB and BR muscles decreased over time. However, EMG amplitudes in the TB muscle were relatively constant until 200 ms after power assistance resulting in greater muscle co-contraction. This could be attributed to the increased postural stability of the human musculature system when the external perturbation on joint movement occurred by power assistance, independent of exercise conditions.

Intraspecific anatomical variations of the extensor tendons of the carpus and digits with a reexamination of their insertion sites in the domestic dog (Canis lupus familiaris): a cadaveric study

BackgroundThe aim of the current study was to investigate the frequency of variations of the extensor tendons of the carpus and digits in the domestic dog (Canis lupus familiaris) with a reexamination of their insertions as well as the morphometric measurements of the tendons and the brachioradialis muscle. In total, we investigated 68 paired thoracic limbs of the domestic dog (16 females and 18 males) which were fixed in a 10% formalin solution.ResultsThe extensor carpi radialis (ECR) tendons showed striking variations in both splitting and insertion sites. In 4.4% of dissections, ECR had three tendons. Of these tendons, the extra tendon either attached independently on the fourth metacarpal bone (one right) or joined its counterpart tendon at the distal end (cross-connections) (one bilateral). It is worth mentioning that one of the ECR tendons split into two or three slips which inserted on the first, second, third, or fourth metacarpal bone in 11 (16.2%) of the specimens. In addition, we found a long tendinous slip originating from the ECR tendons to digit II or III in 7.4% of the distal limbs. The most common type of contribution to digit III was a third tendon of the extensor digiti I et II (ED III) joining the extensor digitorum lateralis (EDL III) with a frequency of 17.6%. In other types of variations, the contribution to digit III was incomplete. A part of the abductor pollicis longus (APL) deep to the superficial part of the flexor retinaculum seemed to continue up to the flexor digitorum superficialis (FDS) tendon.ConclusionsThe rare intraspecific variations of the extensor tendons of the manus described in the current research are valuable from both clinical and phylogenetic perspectives. Nonetheless, their functional importance needs more studies.

SAT239 Deceased Donor Parathyroid Allotransplant For Sever Refractory Iatrogenic Hypoparathyroidism

Abstract Disclosure: K.M. Devon: None. A. Zahedi: None. A. Madani: None. J.D. Pasternak: None. B. Saravana-Bawan: None. A. Humar: None. T. Kathryn: None. While Halstead experimented with dog parathyroid transplantation, the first reported human parathyroid allotransplant appeared in the Annals of Surgery in 1911. Efforts of varying success in restoring calcium homeostasis in patients with refractory hypoparathyroidism after thyroidectomy have included parathyroid transplantation(tx), mainly in immunosuppressed kidney transplant recipients, using cryopreserved, cultured, or hypercellular tissues. Recently, cases of living-donor parathyroid allotransplants have been reported. We present a 46 year-old woman who developed hypoparathyroidism following total thyroidectomy 9 years prior. Treatment included two years of continuous teriparatide via CAD pump. Complications of portacath sepsis and pulmonary emboli, required intensive care. At the time of transplantation, our patient was taking elemental calcium 16 grams daily, magnesium 12 grams daily, calcitriol 8 ug daily, hydroochlorothiazide 25 mg twice daily, and nonetheless requiring biweekly intravenous calcium for symptoms and Calcium levels of 1.6 mmol/l (2.2-2.6 mmol/L). PTH ranged between 0.6- 1.2 pmol/l with poor quality of life. A medically suitable neurologically deceased donor was identified through the provincial organ donation organization. Her cumulative cPRA was 98% (Class I-95%/II-81%). Virtual crossmatch only positive for DQ2 specificity with weak positive B-cell flow crossmatch. Four healthy parathyroids were retrieved. The tissue was minced and placed into pockets in the recipient’s right brachioradialis muscle, under local anaesthesia with sedation. Ischemic time was 2.5 hours. She was induced with basiliximab and received tacrolimus, mycophenolate, and prednisone as immunotherapy. Evidence of biochemical parathyroid function was present post-tx day 9, and she was weaned off all calcium homeostatic medications by day 35, remaining asymptomatic at 7 months at the time of writing, with no calcium infusions. Self-reported quality of life is significantly improved. PTH 0.8-2.8 pmol/L and Calcium 2.06-2.37 mmol/l. To our knowledge this is the first successful fresh normal tissue deceased donor parathyroid transplant in a non-transplant recipient in North America. One study suggests that despite immunosuppression risks, 14 percent of patients would entertain parathyroid allotransplantation. We are currently recruiting additional patients with the aim of demonstrating that deceased donor parathyroid allotransplant using fresh tissue and immunosuppression is a novel viable and curative approach to treat permanent severe hypoparathyroidism. Presentation: Saturday, June 17, 2023

Evaluation of the treatment of distal radial volar fracture by different methods sparing the pronator quadratus

ObjectiveThe traditional volar approach requires the release of the pronator quadratus (PQ) muscle in the treatment of distal radius fractures. However, intraoperative repair of the PQ muscle often fails due to tissue injury and unstable muscle repair. This study compared the outcomes of different methods of sparing the PQ muscle combined with the volar plate in treating distal radius fractures.MethodsA total of 95 patients with distal radius fractures sparing the PQ muscle were enrolled with the brachioradialis (BR) splitting approach (group A, 33 people), the volar plating insertion PQ muscle approach (group B, 35 people) and traditional Henry approach without sparing PQ muscle (group C, 27 people). Postoperative internal fixation, fracture healing and postoperative complications were observed in the three groups. The visual analog scale (VAS) of postoperative wrist pain was compared between three groups. The Dienst joint scale was used to evaluate the wrist function of patients, and imaging indexes were used to evaluate the surgical efficacy.ResultsA total of 95 patients with distal radius fractures were followed up for more than one year after surgery. All fractures obtained good union, with no vascular injury, nerve injury or wound infection. Outcomes at three days, one month and three months all showed no significant differences in postoperative imaging indexes among three groups and no significant differences in various indexes among three groups during the same period. The mean operative time in group C was significantly lower than that in groups A and B. There was significant difference in the mean operation time between group A and group B. The amount of mean operative blood loss or mean bone union time in groups A and B was significantly lower than those in group C. No significant difference was shown in mean operative blood loss or mean bone union time between group A and group B. No significant differences in limb function scores, VAS scores and the mean range of motion existed among three groups at the 12-month postoperative follow-up. However, outcomes assessed one week, one month and three months after surgery demonstrated significant differences in the VAS scores and the mean range of motion among three groups, and the group B had lower VAS score and greater the mean range of motion. According to Dienst score, the excellent rate in groups A, B and C was 91.0% (30/33), 94.2% (33/35) and 85.2% (23/27), respectively, at 12 months after surgery. Tendon irritation occurred in 2 cases and joint stiffness in 1 case in group A. In group B, there were 2 cases traumatic arthritis and 2 cases delayed carpal tunnel syndrome and 1 case tendon irritation. In group C, tendon irritation and delayed carpal tunnel syndrome occurred, respectively, in 3 cases.ConclusionOur results demonstrated that these two different surgical approaches were effective ways to reserve PQ and had good clinical outcomes. The volar plating insertion PQ muscle approach could reduce early postoperative pain, promote early activity and return to normal life, while the BR splitting approach was more advantageous in intraoperative fracture exposure and could shorten the operative time. However, some defects also existed. At 12 months of follow-up, no significant advantage was seen in sparing the PQ muscle. Therefore, surgeons should be aware of their individual characteristics and choose patients carefully.

Duplicated superficial branch of the radial nerve and brachioradialis muscle belly: prevalence and significance.

The superficial branch of the radial nerve (SBRN) is a sensory nerve innervating the dorsoradial part of the hand. It originates in the cubital fossa, runs under the belly of the brachioradialis muscle (BM), emerges from underneath in the distal third of the forearm and continues in the subcutaneous tissue towards the hand. There exist several anatomical variations of its branching and course, including a rare variation of its duplication combined with a duplication of the brachioradialis muscle belly. The aim of this study was to find out the prevalence of this variation on a sample of cadaveric human bodies which has not been reported yet. We have carefully dissected 208 cadaveric upper limbs (Central European population). All cases of limbs containing the variation of a double SBRN and/or a double BM belly were measured and documented. We have identified 2 cases of a double SBRN combined with a double BM belly (0.96%). Both were present in the right forearm of a male donor and in both cases the nerve was impinged by muscle bundles connecting the 2 muscle bellies together. Moreover, we have encountered 1 case of a double SBRN without a double BM belly (0.48%), i.e. the total prevalence of a double SBRN was 1.44%. The duplicated SBRN with the duplicated BM is a relatively rare anatomical variation that might cause complications while performing various surgical procedures in the forearm, moreover it might be a rare cause of Wartenberg's syndrome.

Wavelet Analysis of Respiratory Muscle sEMG Signals during the Physiological Breakpoint of Static Dry End-Expiratory Breath-Holding in Naive Apneists: A Pilot Study.

The wavelet spectral characteristics of three respiratory muscle signals (scalenus (SC), parasternal intercostal (IC), and rectus abdominis (RA)) and one locomotor muscle (brachioradialis (BR)) were analyzed in the time-frequency (T-F) domain during voluntary breath-holding (BH), with a focus on the physiological breakpoint that is commonly considered the first involuntary breathing movement (IBM) that signals the end of the easy-going phase of BH. The study was performed for an end-expiratory BH physiological breaking point maneuver on twelve healthy, physically active, naive breath-holders/apneists (six professional athletes; six recreational athletes, and two individuals in the post-COVID-19 period) using surface electromyography (sEMG). We observed individual effects that were dependent on muscle oxygenation and each person's fitness, which were consistent with the mechanism of motor unit (MU) recruitment and the transition of slow-twitch oxidative (type 1) to fast-twitch glycolytic (type 2) muscle fibers. Professional athletes had longer BH durations (BHDs) and strong hypercapnic responses regarding the expiratory RA muscle, which is activated abruptly at higher BHDs in a person-specific range below 250 Hz and is dependent on the BHD. This is in contrast with recreational athletes, who had strong hypoxic responses regarding inspiratory IC muscle, which is activated faster and gradually in the frequency range of 250-450 Hz (independent of the person and BHD). This pilot study preliminarily indicates that it is possible to noninvasively assess the physiological characteristics of skeletal muscles, especially oxygenation, and improve physical fitness tests by determining the T-F features of elevated myoelectric IC and RA activity during BH.

Coupling Effects of Cross-Corticomuscular Association during Object Manipulation Tasks on Different Haptic Sensations.

The effects of corticomuscular connectivity during object manipulation tasks with different haptic sensations have not been quantitatively investigated. Connectivity analyses enable the study of cortical effects and muscle responses during movements, revealing communication pathways between the brain and muscles. This study aims to examine the corticomuscular connectivity of three Electroencephalography (EEG) channels and five muscles during object manipulation tasks involving contact surfaces of Sandpaper, Suede, and Silk. The analyses included 12 healthy subjects performing tasks with their right hand. Power-Based Connectivity (PBC) and Mutual Information (MI) measures were utilized to evaluate significant differences in connectivity between contact surfaces, EEG channels, muscles, and frequency bands. The research yielded the following findings: Suede contact surface exhibited higher connectivity; Mu and Gamma frequency bands exerted greater influence; significant connectivity was observed between the three EEG channels ( , , ) and the Anterior Deltoid (AD) and Brachioradialis (B) muscles; and connectivity was primarily involved during active movement in the AD muscle compared to the resting state. These findings suggest potential implementation in motor rehabilitation for more complex movements using novel alternative training systems with high effectiveness.

Characteristics of upper limb mass, muscle CSA and stiffness in adolescent baseball players with and without elbow injury

Since elbow injuries are common in adolescent baseball players, this study aimed to determine the relationship between musculoskeletal status and elbow injuries in 47 baseball players aged 12–14 years. Participants answered a questionnaire and had their general body measurements taken. Magnetic resonance imaging was used to evaluate muscle cross sectional areas (CSA) of the upper arm flexor and extensor muscles, and x-ray absorptiometry was used to determine the mass of the upper arm and the total mass of the forearm and hand. Shear wave elastography was used to determine muscle stiffness of the biceps brachii, brachialis, pronator teres, and brachioradialis. An orthopedic surgeon performed a clinical assessment and elbow ultrasonography for each participant to diagnose elbow injuries. The measured values were compared between the elbow injury and control groups using two-sample t-tests. The elbow injury group had significantly higher muscle stiffness in the brachialis (p < 0.001) and brachioradialis (p = 0.004) muscles and greater elbow flexor CSA of the distal upper arm (p = 0.004) than the control group. The total mass of the forearm and hand and the mass ratio of the forearm and hand to the upper arm were significantly greater in the elbow injury group than in the control group (p = 0.002 and p < 0.001). Thus, it may be necessary to increase flexibility of the brachialis and brachioradialis flexible by stretching and massaging in addition to evaluating the mass distal to the elbow and the elbow flexor muscle size of the distal upper arm to manage elbow injury in youth baseball players.Characteristics of Upper Limb Mass, Muscle Cross-Sectional Area and Stiffness in Adolescent Baseball Players with and without Elbow Injury.

Experimental Tests of Effect of Vertical Lifting Height, Horizontal Distance, and Weight Load Lifting Method on Muscle Activation Value Generated Using Electromyography

In industry, manual lifting activities certainly involve muscles and generate risks if done improperly. There are problems in the form of complaints from industrial workers on manual lifting activities that are carried out in a less ergonomic manner. This study aims to determine the effect of lifting factor variables on the resulting level of muscle activation. In this case, three factors are used, namely the lifting method factor, the horizontal distance factor, and the vertical distance factor, each of which has two factor levels to produce eight combinations of lifting factors. Randomization was carried out on research subjects totalling 10 people. Previous research that has been done manually is by calculating the pulse resulting from a lifting activity according to a specified frequency. In this study, monitoring of muscle activity was carried out automatically using an instrument called Electromyography (EMG) at three points of the hand muscles, namely the biceps brachii muscle, triceps brachii muscle, and brachioradialis muscle. The results of this study indicate the best combination based on the value of muscle activation on the biceps brachii muscle, triceps brachii muscle, and brachioradialis muscle which respectively include combination 2 (M1-H2-V1) with a significance value of 0.002, combination 6 (M2-H2 -V1) with a significance value of 0.000 and combination 2 (M1-H2-V1) with a significance value of 0.013. The resulting combination of the best lifting factors can be used as a reference and recommendations for the ideal lifting posture and conditions for workers in minimizing possible injuries

Effect of finger rest positions on upper limb muscle activity during pre-clinical procedures.

This study aimed to observe the effect of different finger rest positions on the muscular activity of the hand, forearm, arm, shoulder, thorax, and neck, as well as on the angular deviation from the neutral position of the neck, trunk, upper arm, and forearm on the working side during pre-clinical procedures. An experimental laboratory study was performed. Response variables were muscle activation of the abductor pollicis, brachioradialis, biceps brachii, deltoid, pectoralis major, and right sternocleidomastoid muscles and angular deviation from the neutral position of the neck, trunk, arm, and forearm during simulated clinical procedures. Independent variable was finger-rest position during cavity preparation (no finger rest, usual rest, and ergonomic rest). Class I cavity preparations (N = 120) were performed on artificial first molars (16, 26, 36, and 46) (N = 120). Muscular activation was assessed by surface electromyography and angular deviations using Software for Postural Assessment (SAPO) version 0.69. One-way analysis of variance and Tukey's or Games-Howell's post-hoc tests were performed (α = 0.05). For the sternocleidomastoid muscle, there was no statistically significant difference between the different rest positions. For the deltoid muscle, work with no finger rest resulted in greater muscle activation (p < 0.001) during work on tooth 36. Regarding the pectoralis major and right brachioradialis muscles, we observed that for both teeth 16 and 26, working with ergonomic rest showed less muscle activation. Muscle activation of the right biceps brachii was higher for work with no rest in both the upper and lower arches, differing significantly only from the usual rest in tooth 16 (p < 0.001), usual rest and ergonomic rest in teeth 26 and 46 (p < 0.001), and only ergonomic rest in tooth 36 (p = 0.044). In the right abductor pollicis muscle, work with ergonomic rest resulted in less muscle activation for cavity preparation in teeth 16, 26, and 36, which was significantly different from work with no rest (p = 0.029, p < 0.001, and p = 0.013, respectively). Regarding angular deviation, it was observed that for tooth 16, there was a greater angular deviation of the arm when performing cavity preparations with no finger rest. For teeth 26 and 46, the ergonomic finger rest provided lower angular deviation from the neutral position of the right arm. For tooth 36, ergonomic rest provided less angular deviation from the neutral neck position. In general, the use of non-active finger rest during simulated cavity preparations, regardless of the type of rest, provided less muscle activation and angular deviation from the neutral position of the body's upper extremity when performing pre-clinical procedures.

Analysis of the wardrobe scale of the stacking operation suitable for the elderly

In order to objectively quantify the comfort of the wardrobe stacking operation based on elderly people's muscle activities and subjective evaluations and to determine appropriate operation heights, eighteen self-care elderly people were selected to conduct the experiment of the wardrobe stacking operation, so that the problem that the existing wardrobe design scale did not meet the needs of Chinese elderly people could be solved. The sEMG indicators of the right upper-limb pectoralis major (PM), biceps brachii (BB), triceps brachii (TB), anterior deltoid (AD), and brachioradialis (BR) were tested. The results of this study were acquired though analyzing sEMG indicators, the fitted curves of the comprehensive indicators obtained by principal component analysis (PCA) and the subjective evaluation scores of 4 groups of subjects (F150, F160, M160, M170). For the wardrobe stacking operation, the biceps brachii, anterior deltoid and pectoralis major were the main power muscles of the upper-limb. The appropriate height ranges of different subject groups were obtained, i.e., F150 was more comfortable in the range of 704–832 mm, while F160 was in the range of 832–896 mm. Besides, M160 was 704–960 mm and M170 was 896–1088 mm. Combined with the results of the subjective evaluations, the suitable height range for stacking operation of all elderly whose heights were between 1500 and 179 mm was 704–1024 mm which could ensure the comfort of the using and the wardrobe layer panel could be adjusted in this range according to the storage categories and spacing distance that elderly people need.