Head Of Muscle Research Articles

Hemodynamic monitoring in the human temporalis muscle using near-infrared spectroscopy

Objective. Altered temporal muscle perfusion is implicated in several painful disorders afflicting orofacial and head regions, including temporomandibular joint dysfunctions, bruxism, and headache. Knowledge about the regulation of blood supply to the temporalis muscle is limited, due to methodological difficulties. The study aimed to test the feasibility of near-infrared spectroscopy (NIRS) monitoring of the human temporal muscle. Approach. Twenty-four healthy subjects were monitored with a 2-channel NIRS: a muscle probe placed over the temporal muscle and a brain probe placed on the forehead. A series of teeth clenching at 25, 50, and 75% of maximum voluntary contraction for 20 s and hyperventilation for 90 s at 20 mmHg of end-tidal CO2 were performed, to elicit hemodynamic changes in muscle and brain, respectively. Main results. In twenty responsive subjects, NIRS signals from both probes were consistently different during both tasks. The absolute change in tissue oxygenation index (ΔTOI) as detected by muscle and brain probes was −9.40 ± 12.28 and 0.29 ± 1.54% during teeth clenching (p < 0.01) at 50% maximum voluntary contraction, while −1.03 ± 2.70 and −5.11 ± 3.81% during hyperventilation (p < 0.01), respectively. Significance. Distinct response patterns were observed from the temporal muscle and prefrontal cortex which proves that this technique is adequate to monitor tissue oxygenation and hemodynamic changes in human temporal muscle. Noninvasive and reliable monitoring of hemodynamics in this muscle will help to extend basic and clinical investigations about the peculiar control of blood flow in head muscles.

Validity and Reliability of 3-D Ultrasound Imaging to Measure Hamstring Muscle and Tendon Volumes

The validity and reliability of 3-D ultrasound (US) in estimation of muscle and tendon volume was assessed in a very limited number of muscles that can be easily immersed. The objective of the present study was to assess the validity and reliability of muscle volume measurements for all hamstring muscle heads and gracilis (GR), as well as tendon volume for the semitendinosus (ST) and GR using freehand 3-D US. Three-dimensional US acquisitions were performed for 13 participants in two distinct sessions on separate days, in addition to one session dedicated to magnetic resonance imaging (MRI). Volumes of ST, semimembranosus (SM), biceps femoris short (BFsh) and long (BFlh) heads, and GR muscles and from the tendon from semitendinosus (STtd) and gracilis (GRtd) were collected. The bias and the 95% confidence intervals of 3-D US compared with MRI ranged from -1.9 mL (-0.8%) to 1.2 mL (1.0%) for muscle volume and from 0.01 mL (0.2%) to -0.03 mL (-2.6%) for tendon volume. For muscle volume assessed using 3-D US, intraclass correlation coefficients (ICCs) ranged from 0.98 (GR) to 1.00, and coefficients of variation (CV) from 1.1% (SM) to 3.4% (BFsh). For tendon volume, ICCs were 0.99, and CVs between 3.2% (STtd) and 3.4% (GRtd). Three-dimensional US can provide a valid and reliable inter-day measurement of hamstrings and GR for both muscle and tendon volumes. In the future, this technique could be used as an outcome for strengthening interventions and potentially in clinical environments.

Myoelectric activity and improvements in strength and hypertrophy are unaffected by the ankle position during prone leg curl exercise – a within person randomized trial

ABSTRACT To examine the effect of ankle position (i.e. gastrocnemius muscle length) on training outcomes during leg curl exercise, we recruited untrained and trained healthy adults to participate in two separate experiments. In Experiment 1, we studied the acute influence of ankle position on knee flexor myoelectric (EMG) activity during leg curl exercise in a group of trained and a separate group of untrained adults. In Experiment 2, we studied the effects of ankle position on knee flexors muscle thickness and torque across a 10-week training protocol in trained adults. We hypothesized that leg curl exercise with the ankle in a plantarflexed position would enhance EMG activity, muscular strength, and hamstrings muscle thickness. We randomized the legs within a person to perform leg curl exercise with one in a plantarflexed position and the other in a dorsiflexed position. Experiment 1 revealed no significant differences between ankle positions in the EMG activity of hamstring muscle in either group (all p > 0.05). Experiment 2 revealed a significant pre- to post-intervention increase in biceps femoris long head (BFLH) muscle thickness (p = 0.026) and isometric torque (p = 0.03), but there were no significant effects of the ankle position (p = 0.596) or interaction between ankle position and timepoint for these variables (p = 0.420). In sum, the ankle position did not have acute effects on hamstrings EMG activity, nor did it affect strength and hypertrophy adaptations after 10-weeks of leg curl exercise training. Interestingly, however, the limb which performed leg curl exercise in a dorsiflexed position performed a higher total training volume. Highlights Different ankle positions (i.e. dorsiflexion or plantarflexion) do not affect hamstrings EMG activity during prone leg curl exercise. Different ankle positions show similar adaptation in strength and hypertrophy of biceps femoris long head after 10 weeks of training. Training in the plantarflexed position may be useful for time-constrained individuals, allowing similar training adaptations with smaller training volume.

52. Varying Muscle Graft to Nerve Fiber Size and its Impact on Regenerative Peripheral Nerve Interface (RPNI) Reinnervation

PURPOSE: Currently there are more than 1.6 million people who suffer from limb loss. Regenerative Peripheral Nerve Interfaces (RPNI) currently exist as a method of capturing peripheral nerve signals for prosthetic control and preventing neuroma formation. While it is typically recommended that RPNIs are constructed to be 3 x 1 x 1.5 cm for human patients and approximately 150 mg in rat models, there is currently no recommendations or data to guide selection of muscle graft size for different nerve sizes. This consideration is especially important for RPNI construction as these factors may influence maximal optimal reinnervation for motor signal capture and neuroma prevention. The purpose of this study was to assess the ideal ratio of nerve size to muscle graft size for maximal RPNI compound muscle action potential (CMAP) signaling. METHODS: A total of 46 rats were assigned to 6 experimental groups that varied the size of nerve and muscle graft for RPNI creation. Extensor digitorum longus (EDL) was harvested, and different combinations of its four muscle heads were removed to create different size muscle grafts: 20% EDL, 60% EDL, and 100%EDL. To adjust nerve size, the tibial nerve was either left untouched or divided longitudinally along the nerve for approximately 15 cm. Depending on the experimental group, either 33% or 100% of the tibial nerve was implanted into the final muscle graft. All rats underwent a 3-month maturation period before undergoing electrophysiologic testing for obtaining CMAPs. An ANOVA test with post hoc analysis was performed to test for significant differences among the groups. RESULTS: For 33% nerve groups, maximum average CMAPs occurred at 2.2 mV with the 60% EDL RPNI. However, this average was not statistically different from that of the 20% (0.47 mV) or 100% (1.85 mV) EDL RPNI. With the 100% nerve group, maximum CMAP of the 100% EDL RPNI (4.5 mV) was significantly greater than that of the 20% (1.7 mV) or 60% (2.3 mV) EDL RPNIs. Furthermore, the maximum average CMAPs of the 100% nerve was significantly higher from that of the 33% nerve. CONCLUSIONS: This study’s findings suggest RPNI regeneration by large nerves requires the full EDL donor muscle for maximal reinnervation in the rat model, and that full reinnervation leads to significantly larger motor signals compared to smaller nerves. Thus, muscle graft size optimization to nerve size may be necessary in the clinical setting.

Morphological variability of the pectoralis major muscle in human fetuses

BackgroundThe pectoralis major muscle is located in the anterior chest wall. In most cases, it is divided into clavicular, sternal (sternocostal) and abdominal heads. The aim of this study is to demonstrate and classify the morphological variability of the pectoralis major muscles in human fetuses. Material and methodsClassical anatomical dissection was performed on 35 human fetuses aged 18–38 weeks of gestation at death were examined. (17 female, and 18 male, 70 sides; fixed in 10% formalin solution). The fetuses were obtained from spontaneous abortion after informed consent of both parents and through deliberate donation to the Medical University anatomy program. Upon dissection, the following morphological features were assessed: the morphology of the pectoralis major, the possible occurrence of accessory heads, the possible absence of some head, and morphometric measurements of each head of the pectoralis major muscle. ResultsFive types of morphology (based on number of bellies) were observed in the fetuses. Type I was characterized by a single claviculosternal belly (10% of all samples). Type II comprised the clavicular and sternal heads (37.1%). Type III comprised three clavicular, sternal and abdominal heads (31.4%). Type IV (17.2%) was characterized by four muscle bellies and was divided into four subtypes. Type V (4.3%), was represented by five parts, and was divided into two subtypes. ConclusionsDue to its embryological development, the PM demonstrates great variability in the numbers of its parts. The most common type was the PM with two bellies, in line with previous studies which also distinguished only clavicular and sternal heads.

Relationship between shear elastic modulus and passive muscle force in human hamstring muscles using a Thiel soft-embalmed cadaver.

Assessing muscle flexibility and architecture is important for hamstring strain injury (HSI) prevention. We investigated the relationship between shear modulus and passive force in hamstring muscles at different sites and the effect of muscle architecture on the slope of the shear modulus-passive force using shear wave elastography (SWE). The biceps femoris long head (BFlh), semitendinosus (ST), and semimembranosus (SM) muscles were dissected from nine Thiel-embalmed cadavers and fixed to a custom-made mechanical testing machine. Calibrated weights (0-1800g) were applied gradually in 150-g increments. The shear modulus and anatomical cross-sectional area (ACSA) were measured at proximal, central, and distal points using SWE. The muscle mass and length were measured before the loading test. The shear modulus-passive load relationship of each tested muscle region was analyzed by fitting a least-squares regression line. The increase in shear modulus slope per unit load was calculated and compared between the muscles before and after normalization by the muscle mass, length, and ACSA. The shear modulus and passive force for all hamstring muscles in each region showed a statistically significant linear correlation. Furthermore, the increase in shear modulus slope was greater for BFlh and ST than for SM (P < 0.05), but after normalization by the muscle length and ACSA, there were no significant differences among the muscles. The local mechanical properties of individual hamstring muscles can be indirectly estimated using SWE, and the slope of increase in shear modulus reflects characteristics of the muscle architecture.

Accessory head of the semitendinosus muscle: an unusual variation.

Various studies regarding the morphology of the muscles of the hamstring compartment have exhibited anatomical variations in terms of origin or insertion points. However, variation of the semitendinosus muscle is uncommon. In this case we report an accessory head of the semitendinosus muscle. During routine dissection for medical teaching purposes, a unilateral morphological variant of the semitendinosus muscle was noted on the left side in an 82-year-old female. The accessory head of the semitendinosus muscle originated lateral to the midpoint of the semitendinosus muscle. Fibres of the accessory head originated from the medial border of the long head of biceps femoris as well as the midpoint of the semitendinosus. The accessory head had a common insertion point with the semitendinosus muscle. This case report adds to the existing body of knowledge about the semitendinosus muscle, which is of anatomical and clinical value. Knowledge of the anatomical variants is essential for anatomists and clinicians and may avoid misinterpretation during diagnostic procedures.

HTLV-1-associated myelopathy/tropical spastic paraplegia with sporadic late-onset nemaline myopathy: a case report

BackgroundSporadic late onset nemaline myopathy (SLONM) is a muscle disorder characterized by the presence of nemaline rods in muscle fibers. SLONM has no known genetic cause but has been associated with monoclonal gammopathy of undetermined significance and with human immunodeficiency virus (HIV) infection. Human T-cell leukemia virus-1 (HTLV-1) is a known causative agent of adult T-cell leukemia/lymphoma and HTLV-1 associated myelopathy/tropical spastic paraplegia (HAM/TSP), a chronic inflammatory neurological disease. HTLV-1 has been reported to be implicated in inflammatory myopathies, as well as in HIV infection.; however, there have been no reports of an association between HTLV-1 infection and SLONM to date.Case presentationA 70-year-old Japanese woman presented with gait disturbance, lumbar kyphosis, and respiratory dysfunction. The diagnosis of HAM/TSP with SLONM was made based on characteristic clinical symptoms of HAM/TSP, such as spasticity in the lower extremities, and cerebrospinal fluid test results; and of SLONM, such as generalized head drooping, respiratory failure, and muscle biopsy results. Steroid treatment was initiated and improvement in her stooped posture was observed after 3 days of treatment.ConclusionThis is the first case report of SLONM combined with HTLV-1 infection. Further studies are needed to elucidate the relationship between retroviruses and muscle diseases.

Effects of Posture and Walking on Tibial Vascular Hemodynamics Before and After 14 Days of Head-Down Bed Rest.

Human skeletal hemodynamics remain understudied. Neither assessments in weight-bearing bones during walking nor following periods of immobility exist, despite knowledge of altered nutrient-artery characteristics after short-duration unloading in rodents. We studied 12 older adults (8 females, aged 59 ± 3 years) who participated in ambulatory near-infrared spectroscopy (NIRS) assessments of tibial hemodynamics before (PRE) and after (POST) 14 days of head-down bed rest (HDBR), with most performing daily resistance and aerobic exercise countermeasures during HDBR. Continual simultaneous NIRS recordings were acquired over the proximal anteromedial tibial prominence of the right lower leg and ipsilateral lateral head of the gastrocnemius muscle during supine rest, walking, and standing. During 10 minutes of walking, desaturation kinetics in the tibia were slower (time to 95% nadir values 125.4 ± 56.8 s versus 55.0 ± 30.1 s, p = 0.0014). Tibial tissue saturation index (TSI) immediately fell (-9.9 ± 4.55) and did not completely recover by the end of 10 minutes of walking (-7.4 ± 6.7%, p = 0.027). Upon standing, total hemoglobin (tHb) kinetics were faster in the tibia (p < 0.0001), whereas HDBR resulted in faster oxygenated hemoglogin (O2Hb) kinetics in both tissues (p = 0.039). After the walk-to-stand transition, changes in O2Hb (p = 0.0022) and tHb (p = 0.0047) were attenuated in the tibia alone after bed rest. Comparisons of NIRS-derived variables during ambulation and changes in posture revealed potentially deleterious adaptations of feed vessels after HDBR. We identify important and novel tibial hemodynamics in humans during ambulation before and after bed rest, necessitating further investigation. © 2023 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Gastruloids as an in vitro model of Cardiopharyngeal Mesoderm specification into skeletal and cardiac muscle lineages

Cardiopharyngeal mesoderm (CPM) contributes to the formation of the heart and head muscles. These muscles are both affected in rare congenital disorders including velocardiofacial syndrome or cardiofaciocutaneous syndrome. While the mechanisms governing CPM specification remain relatively unknown, there is a lack of an in vitro platform that would allow the differentiation of both head and heart muscles. Develop embryonic organoids from mouse embryonic stem cells (mESC), also called gastruloids, to form and specify CPM toward the cardiac and muscle lineages. Use in vitro 3D culture to develop and characterize embryonic organoid. By using single-cell RNAseq, and high-resolution imaging of single molecule FISH experiments, we confirm that the CPM is established in gastruloids, with a kinetic of gene expression that is similar to the mouse embryo. We identify different subpopulations of cardiomyocytes and skeletal muscles most likely corresponding to the different cardiac chambers and head and trunk skeletal muscles. These findings unveil the potential of mESCs-derived gastruloids to undergo CPM specification in both head and heart lineages, allowing the investigation of the mechanisms of CPM specification in development and how this could be affected in congenital disorders.

Nervous coccidiosis in a calf

In this case report, a 9-month Swiss brown calf has been reported with neurological symptoms including seizures, opisthotonus, hyperesthesia, nystagmus, convulsions of the head and extremity muscles, watery brown faeces and mild blood in faeces. Eimeria spp. oocyst was found in the parasitological examination of the faeces, and it was suspected of nervous coccidiosis. When the brain tissue was examined, the numerous different forms of Eimeria spp were histopathologically detected in the brain parenchyma and brain capillaries. Eimeria spp which were found in the brain and large intestinal tissues were confirmed as Eimeria zuernii using specific primers with qRT-PCR. This case report emphasizes that Eimeria zuernii is located in the brain tissue of cattle for the first time in the world. We suspect that these agents may travel to the brain through the enteric blood vessels, and all the neurological symptoms detected in this calf may be due to the presence of these agents in the brain tissue. Therefore, this could be crucial knowledge on the pathogenesis of nervous coccidiosis.

Microscopic changes in experimentally damaged rabbit muscles under the influence of transplanted mesenchymal stem cells

The relevance of the work is related to the possibility of artificially adjusting the intensity of skeletal muscle tissue regeneration in animals, which will significantly affect the tactics of rehabilitation treatment of muscle injuries in the future. The purpose of the research was to determine the effectiveness of the transplanted mesenchymal stem cells on the recovery processes in experimentally injured rabbit muscles. The method of histological examination of microscopic changes in the experimentally damaged muscle tissue of the pelvic head of the biceps femoris muscle of rabbits was used. Microscopic studies of the regeneration process of experimentally damaged striated muscle tissue established that in animals after intramuscular injection of allogeneic mesenchymal stem cells, connective tissue developed around the defect on day 2 of the experiment. On day 4, a large number of stem cells were detected in the connective tissue at the site of muscle tissue damage. On day 6, only relatively small foci of muscle tissue regeneration were observed in this area. On day 8, only small focal accumulations of stem cells were detected in this location. On the 10th day after intramuscular injection of mesenchymal stem cells, newly developed muscle fibres appeared at the site of injury. On the 14th day after intramuscular injection of mesenchymal stem cells, fully developed muscle fibres and intermuscular connective tissue were observed at the site of injury. In rabbits, after intramuscular injection of allogeneic mesenchymal stem cells, all regenerative processes were more active than in animals of other experimental groups and were completely completed by day 14 of the experiment. The practical value of the results obtained is to clarify the patterns of development of reparative processes in the damaged muscle area and to determine the effectiveness of using transplanted allogeneic mesenchymal stem cells in stimulating recovery processes, which is important to consider in the treatment of muscle injuries using regenerative therapy

Effect of Shirodhara in the Management of Vatika Shiroroga: A Case Study

The most typical primary headache is called Vatika Shiroroga (Tension Headache). According to the International Headache Society, 46% of people worldwide experience headaches in general, 42% experience tension-type headaches, 11% experience migraines, and roughly 3% experience chronic tension headaches. It is produced due to contraction of the muscles of head &amp; neck &amp; psychological factors like stress and strain aggravates the condition. Shirodhara is a significant Ayurvedic therapeutic method which has significant effect on the body's neuro, immuno, physio and psychological systems. Several studies have been carried out to evaluate the efficacy of Shirodhara in many diseases. The trial drug Dashamoola Taila for Shirodhara procedure showed highly significant reduction in symptoms like Ghat-Sambhidhyate (Cutting type of pain in posterior aspect of neck), Sankhanistoda, Akshinishkasanvat peeda, Bhrumadhya peeda, Nishakal Ativedna etc. Thus, Shirodhara with Dashamoola Taila is effective in the management of the Vatika Shiroroga (Tension Headache). The patient received Shirodhara treatment with Dashmoola Taila for 3 sessions of 7 days each with a gap of 3 days.

The AIUM Practice Parameter for the Performance of the Musculoskeletal Ultrasound Examination.

The AIUM Practice Parameter for the Performance of the Musculoskeletal Ultrasound Examination.

Possible Points of Ulnar Nerve Entrapment in the Arm and Forearm: An Ultrasound, Anatomical, and Histological Study.

Ulnar nerve entrapment is one of the most common entrapment neuropathies, usually occurring in the cubital tunnel of the elbow and in Guyon's canal of the wrist. However, it can also occur at other anatomical locations. Our aim was to review other possible locations of ulnar nerve entrapment in an ultrasound and anatomical study. Eleven upper limbs from eight adult corpses were ultrasonographically examined and subsequently dissected in a dissection laboratory. Four specific anatomical points were analysed, and any anatomical variations were documented. Moreover, six samples of the nerve were taken for histological analysis. Distinct anatomical relationships were observed during ultrasound and dissection between the ulnar nerve and the medial intermuscular septum, the triceps aponeurosis, Osborne's fascia at the elbow, the arcuate ligament of Osborne and the intermuscular aponeurosis between the flexor carpi ulnaris and the flexor digitorum superficialis muscles. A statistical study showed that these locations are potential areas for ulnar nerve compression. In addition, a fourth head of the triceps brachii muscle was found in some specimens. Results demonstrate that ultrasound is a good tool to investigate ulnar nerve entrapment neuropathy and to identify other anatomical points where the nerve can remain compressed.

Activity Distribution Among the Hamstring Muscles During the Nordic Hamstring Exercise: A Multichannel Surface Electromyography Study.

This study assessed activity distribution among the hamstring muscles during the Nordic hamstring exercise (NHE). The objective was to compare muscle activity between and within muscles during the NHE to add insights in its underlying protective mechanism. Through multichannel electromyography, we measured muscle activity in male basketball players during the NHE. Electromyography was assessed at 15 locations: 5 for biceps femoris long head, 4 for semitendinosus, and 6 for semimembranosus. For each percent of the eccentric phase of the NHE, muscle activity was calculated for each electrode location within each hamstring muscle individually. To quantify whole muscle head activity, means and variances across electrodes within each muscle were calculated. Thirty-five noninjured participants were included (mean age, 18 [2]y; mass, 87 [12]kg; height, 192 [9]cm). Heterogeneous muscle activity was found between 38% and 62% and over the whole eccentric contraction phase within the semitendinosus and the semimembranosus, respectively. Muscle activity of the semitendinosus was significantly higher than that of the biceps femoris long head. During the NHE, the relative contribution of the semitendinosus is the highest among hamstring muscles. Its strong contribution may compensate for the biceps femoris long head, the most commonly injured hamstring muscle head.

Superficial anatomic landmarks can be used to triangulate the location of canine peripheral lymphocentrums: superficial cervical, axillary, and superficial inguinal.

To utilize the geometry of superficial anatomic landmarks to guide incisional location and orientation for peripheral lymphadenectomy, document deep anatomic landmarks for lymphocentrum identification, and develop novel surgical approaches to the superficial cervical, axillary, and superficial inguinal lymphocentrums in dogs. 12 canine cadavers. 2 cadavers were used for a pilot investigation to determine optimal body positioning, select superficial anatomic landmarks for lymphocentrum identification, and evaluate novel surgical approaches to the 3 lymphocentrums. These lymphocentrums were then dissected in 10 additional cadavers using these novel surgical approaches. Measurements of the distances from lymphocentrum to landmark and between landmarks were obtained for each lymphocentrum. Deep anatomic landmarks were recorded for each dissection. The mean and SD were calculated for each measurement and used to develop geometric guidelines for estimating the location of each lymphocentrum for these surgical approaches. Each peripheral lymphocentrum was found in the same location relative to the respective, predetermined, superficial, anatomic boundaries in all cadavers. Briefly, the superficial landmarks to each lymphocentrum were as follows: (1) superficial cervical: wing of atlas, acromion process of scapula, greater tubercle of humerus; (2) axillary: caudal border of transverse head of superficial pectoral muscle, caudal triceps muscle, ventral midline; and (3) superficial inguinal: origin of pectineus muscle, ipsilateral inguinal mammary gland, ventral midline. The proposed superficial and deep surgical landmarks were identified within every cadaver. The previously undescribed surgical approaches were effective for lymphocentrum identification. Anatomic landmarks provided in this study may help reduce surgical time and tissue trauma during peripheral lymphadenectomy in dogs. This study was also the first to describe a surgical approach to the superficial inguinal lymphocentrum and ventral approaches to the superficial cervical and axillary lymphocentrums and provided previously unpublished anatomic landmarks for a lateral approach to the superficial cervical lymphocentrum.

Modulating the Nordic Hamstring Exercise From "Zero to Hero": A Stepwise Progression Explored in a High-Performance Athlete.

The Nordic hamstring exercise (NHE) is commonly implemented to selectively improve eccentric knee-flexor strength. However, the standard version of the exercise (leveled shanks, extended hip joint) is too strenuous for most individuals, whose muscle activity rapidly decreases at extended knee angles. Hitherto, a gradual approach to the exercise has been missing. In this exploratory case study, we investigated elite performance to introduce a stepwise progression to the NHE. To determine the extent to which exercise modifications (shank inclination, additional load, hip flexion) altered NHE mechanics. One male long jumper (age = 33 years, height = 171 cm, mass = 69 kg) with high-level expertise in the NHE performed 20 exercise variations. The corresponding kinematics, kinetics, and electromyographic activity of the biceps femoris long head (BFlh) and semitendinosus (ST) muscles were evaluated. Exercise variations demonstrated gradually increased peak moments from 69% (zigzag pose) to 154% (inclined bent single-legged version) versus a standard NHE. Shank inclination and additional load elicited small to moderate effects on peak moments, BFlh, and ST (0.24 ≤ d ≤ 0.72), whereas hip flexion largely affected all tested variables (2.80 ≤ d ≤ 6.66), especially muscle activity (BFlh = -63%; ST = -55% of maximal voluntary isometric contraction). These insights will help practitioners and scientists design multifaceted stepwise NHE progressions by creating differentiated stimuli that best match the strength capacities of individuals and address their specific needs.

Variant plantaris muscle with degenerated accessory head: Gross and histological analysis.

The variant plantaris muscle has itself been reported to have variable presentations. Here, we report an unusual finding of the plantaris muscle and report its gross and histological findings. A duplicated head of the plantaris muscle was identified in the right leg of an adult cadaver age and sex. The more anterior head of the muscle was in the typical location and originated from the superolateral condyle of the femur. However, the more posteriorly located head arose from the iliotibial band at the level of the distal thigh. The two heads united and continued as the typical distal tendon of the plantaris muscle to insert into the calcaneus tendon (Achilles). The normally positioned head of the plantaris muscle was found to be composed of typical skeletal muscle fibres. However, the accessory head of the plantaris muscle was found to be severely degenerated and infiltrated with adipose tissue. We report a duplicated head of the plantaris muscle. Histologically, the accessory head was degenerated and infiltrated with adipose tissue. To our knowledge, this is the first report of such a case. Further cases are now necessary to further elucidate this finding.

The ulnar head of the pronator teres muscle originating from the third head of the biceps brachii: a very rare case.

The biceps brachii is located in the anterior compartment of the arm, which can show numerous morphological variations. During anatomical dissection, an interesting additional muscle was found: the third head of the biceps brachii originated from the short head of the same muscle. The 97.77 mm long muscle belly was directed medially over the arm and then passed into the common tendon (15.97 mm), which thereafter split into aponeurosis and tendon. The 26.33 mm aponeurosis passed and joined the fascia of the forearm. The tendon of the third head of the biceps brachii then gave rise to the ulnar head of the pronator teres muscle. Such an accessory structure could cause neurovascular compression involving the brachial artery and median nerve. Knowledge of the morphological variability of this region is essential not only for anatomists but also for clinicians.