The neural mechanisms of manual dexterity.

The hand endows us with unparalleled precision and versatility in our interactions with objects, from mundane activities such as grasping to extraordinary ones such as virtuoso pianism. The complex anatomy of the human hand combined with expansive and specialized neuronal control circuits allows a wide range of precise manual behaviours. To support these behaviours, an exquisite sensory apparatus, spanning the modalities of touch and proprioception, conveys detailed and timely information about our interactions with objects and about the objects themselves. The study of manual dexterity provides a unique lens into the sensorimotor mechanisms that endow the nervous system with the ability to flexibly generate complex behaviour.

Phylogenetic differences in the morphology and shape of the central sulcus in great apes and humans: implications for the evolution of motor functions.

The central sulcus divides the primary motor and somatosensory cortices in many anthropoid primate brains. Differences exist in the surface area and depth of the central sulcus along the dorso-ventral plane in great apes and humans compared to other primate species. Within hominid species, there are variations in the depth and aspect of their hand motor area, or knob, within the precentral gyrus. In this study, we used post-image analyses on magnetic resonance images to characterize the central sulcus shape of humans, chimpanzees (Pan troglodytes), gorillas (Gorilla gorilla), and orangutans (Pongo pygmaeus and Pongo abelii). Using these data, we examined the morphological variability of central sulcus in hominids, focusing on the hand region, a significant change in human evolution. We show that the central sulcus shape differs between great ape species, but all show similar variations in the location of their hand knob. However, the prevalence of the knob location along the dorso-ventral plane and lateralization differs between species and the presence of a second ventral motor knob seems to be unique to humans. Humans and orangutans exhibit the most similar and complex central sulcus shapes. However, their similarities may reflect divergent evolutionary processes related to selection for different positional and habitual locomotor functions.

Humanlike manual activities in Australopithecus.

The evolution of the human hand is a topic of great interest in paleoanthropology. As the hand can be involved in a vast array of activities, knowledge regarding how it was used by early hominins can yield crucial information on the factors driving biocultural evolution. Previous research on early hominin hands focused on the overall bone shape. However, while such approaches can inform on mechanical abilities and the evolved efficiency of manipulation, they cannot be used as a definite proxy for individual habitual activity. Accordingly, it is crucial to examine bone structures more responsive to lifetime biomechanical loading, such as muscle attachment sites or internal bone architecture. In this study, we investigate the manual entheseal patterns of Australopithecus afarensis, Australopithecus africanus, and Australopithecus sediba through the application of the validated entheses-based reconstruction of activity method. Using a comparative sample of later Homo and three great ape genera, we analyze the muscle attachment site proportions on the thumb, fifth ray, and third intermediate phalanx to gain insight into the habitual hand use of Australopithecus. We use a novel statistical procedure to account for the effects of interspecies variation in overall size and ray proportions. Our results highlight the importance of certain muscles of the first and fifth digits for humanlike hand use. In humans, these muscles are required for variable in-hand manipulation and are activated during stone-tool production. The entheses of A. sediba suggest muscle activation patterns consistent with a similar suite of habitual manual activities as in later Homo. In contrast, A. africanus and A. afarensis display a mosaic entheseal pattern that combines indications of both humanlike and apelike manipulation. Overall, these findings provide new evidence that some australopith species were already habitually engaging in humanlike manipulation, even if their manual dexterity was likely not as high as in later Homo.

Grip and pinch strength prediction models based on hand anthropometric parameters: an analytic cross-sectional study.

BACKGROUND: Hand grip strength (HGS) and pinch strength are important clinical measures for assessing the hand and overall health. OBJECTIVE: The aim of the present study is to predict HGS and pinch strength based on 1 hand anthropometry, and (2) body anthropometric parameters using machine learning. METHODS: A Secondary analysis was conducted on 542 participant aged 30-60 years from the Persian Organizational Cohort study in Mashhad University of Medical Sciences. Artificial Neural Network (ANN) were fitted as prediction model. The dataset was divided into two sets: a training set, which comprised 70% of the data, and a test set, which comprised 30% of the data. Various combinations of the hand anthropometric, demographic, and body anthropometric parameters were used to determine the most accurate model. RESULTS: The optimal HGS model, using the input of gender, body mass, and hand anthropometric parameters of length (both total length and palm), maximum width, maximum breadth, and hand shape index, achieved nearly equal accuracy to the model that incorporated all variables (RMSE = 5.23, Adjusted R2 = 0.67). As for pinch strength, gender, hand length (both total length and palm), maximum width, maximum breadth, hand shape index, hand span, and middle finger length came closest to the model incorporating all variables (RMSE = 1.20, Adjusted R2 = 0.52). CONCLUSION: This ANN model showed that hand anthropometric parameters of total length, palm length, maximum width, maximum breadth, and the hand shape index, emerge as optimal predictors for both HGS and HPS. Body anthropometric factors (e.g., body mass) play roles as predictors for HGS, whereas their influence on pinch strength appears to be less pronounced. LEVEL OF EVIDENCE: Level III (Diagnosis). TRIAL REGISTRATION: Not applicable.

Evaluation of various anthropometric measurements for the determination of the occlusal vertical dimension.

STATEMENT OF PROBLEM: Studies on anthropometric measurements, one of the methods used in determining the occlusal vertical dimension, have been limited to the evaluation of only a few facial and hand parameters. PURPOSE: The purpose of this clinical study was to determine the possible relationships between all facial and hand measurements reported in the literature and assumed to be correlated with the occlusal vertical dimension and reveal their proportional relationships. MATERIAL AND METHODS: The study included a total of 271 participants, 136 women (30.37 ±8.09 years) and 135 men (30.42 ±8.49 years). A total of 36 measurements, including 4 occlusal vertical dimensions and 24 facial and 8 hand measurements, were obtained for each participant. Measurements were obtained directly from the soft tissue landmarks of the participants using 4 digital vernier calipers (Accud Digital Caliper; Accud), each designed for a different purpose. The normality of the parameters was analyzed using the Kolmogorov-Smirnov and Shapiro-Wilk tests, and the relationships between the parameters were analyzed using the Pearson correlation analysis (α=.05). Simple and multivariate linear regression analyses were also performed. Correlation coefficients were categorized as strong (r≥0.6), moderate (0.6>r>0.3), and weak (r≤0.3). Moreover, regression formulas were established for strongly correlated parameters. RESULTS: Facial and hand measurements that showed strong correlations with occlusal vertical dimension measurements were the distance between the pupil of the eyes, the pupil of the eye-to-cheilion, sellion-to-stomion, sellion-to-labiale inferius, stomion-to-pogonion, meatus-to-exocanthion, and exocanthion-to-cheilion distances and the 4-finger width measurement between the index and little fingers. CONCLUSIONS: Certain anthropometric facial and hand measurements and regression formulas derived from the parameters that revealed strong correlations can be used to determine the occlusal vertical dimension.

Ultrasound identification of hand and wrist anatomical structures by hand surgeons new to ultrasonographic techniques.

PURPOSE: Ultrasound is becoming an essential tool for hand surgeons, but most of them are trained on the job, without any diploma or dedicated training. The aim of this study was to assess the ability of hand surgeons new to ultrasound to identify hand and wrist anatomical structures. METHODS: A monocentric study was conducted from January 2022 to April 2022. Ten residents and five attending hand surgeons, ultrasound novices, were involved in this study. The participants underwent two tests, wherein they were required to identify 17 anatomical structures using ultrasound, on the same subject. The second test was similar and carried out 2 to 6 weeks later by all participants. The number of structures successfully identified and if it was the case, the detection time per structure, were recorded. The correlations between participants age, years of surgical experience, surgical background (orthopedic or plastic) and the ability to perform immediately during the first test or to progress between the two tests were also assessed. RESULTS: The average number of structures identified during the first test (T1) was 14.1+/-2.1 (82.9%), versus 16.2+/-0.8 (95.3%) structures during the second test (T2) (p = 0.001). The mean detection time per structure was 53.4 +/- 18.9 s during T1 versus 27.7 +/- 7.2 s during T2 (p < 0.0001). A moderate negative correlation between the progression in the number of anatomical structures identified between the two tests and the years of surgical experience (ρ=-0.56; p = 0.029) was found. The other parameters were neither correlated with the ability to perform at the first test nor with the progression between the two tests. CONCLUSION: Hand surgeons new to ultrasound are most of the time able to identify hand and wrist anatomical structures. Comparison of their first and second tests showed significant potential for improvement in anatomical structure identification and detection time of those, especially in surgeons with limited surgical experience.

Assessment of the Vertical Dimension of Occlusion Using Palm Width and Finger Length.

Background and Objectives: The vertical dimension of occlusion's (VDO) assessment is a highly important issue in the everyday dentist's practice. Patients with unstable occlusion, lost occlusal stops, extensive tooth loss in the lateral area, or complete edentulism need a proper assessment of the VDO before the prosthetic restoration is carried out. Subjective and objective methods were used over time for the restoration of VDO. The study aimed to investigate the possible correlation between finger length, palm width and the vertical dimension of occlusion. Materials and Methods: Assessment of the VDO for 236 subjects, Romanian and French dental students, was performed using the Willis Bite Gauge. The left hand of the subjects was scanned using a flat-bed scanner, and then measurements of palm width and finger length were carried out for each subject. Comparison between VDO values and finger length/palm width was conducted using one-way ANOVA and Student t-Test. Results: Higher VDO average values were found in French subjects compared with Romanian students. The same results were found according to gender; in both female and male subjects, lower values of VDO were found in the Romanian group. Higher values were obtained for women within each group when comparing to men. Statistically significant correlations of the analyzed parameters and VDO values were found. Higher statistical correlations of the studied variables were found for men compared to women in both groups. The highest statistical correlation was obtained between the VDO and the palm width measured at the fingerbase, followed by the middle finger length. Conclusions: The results showed the highest statistical correlation between the vertical dimension of occlusion and the palm width measured at the fingers' base. Statistical correlations were also found between the VDO and the middle finger length. Simple formulas using finger length/palm width can be used for a rapid VDO determination.

Cortical bone distribution of the proximal phalanges in great apes: implications for reconstructing manual behaviours.

Primate fingers are typically in direct contact with the environment during both locomotion and manipulation, and aspects of external phalangeal morphology are known to reflect differences in hand use. Since bone is a living tissue that can adapt in response to loading through life, the internal bone architecture of the manual phalanges should also reflect differences in manual behaviours. Here, we use the R package Morphomap to analyse high-resolution microCT scans of hominid proximal phalanges of digits 2-5 to determine whether cortical bone structure reflects variation in manual behaviours between bipedal (Homo), knuckle-walking (Gorilla, Pan) and suspensory (Pongo) taxa. We test the hypothesis that relative cortical bone distribution patterns and cross-sectional geometric properties will differ both among extant great apes and across the four digits due to locomotor and postural differences. Results indicate that cortical bone structure reflects the varied hand postures employed by each taxon. The phalangeal cortices of Pongo are significantly thinner and have weaker cross-sectional properties relative to the African apes, yet thick cortical bone under their flexor sheath ridges corresponds with predicted loading during flexed finger grips. Knuckle-walking African apes have even thicker cortical bone under the flexor sheath ridges, as well as in the region proximal to the trochlea, but Pan also has thicker diaphyseal cortices than Gorilla. Humans display a distinct pattern of distodorsal thickening, as well as relatively thin cortices, which may reflect the lack of phalangeal curvature combined with frequent use of flexed fingered hand grips during manipulation. Within each taxon, digits 2-5 have a similar cortical distribution in Pongo, Gorilla and, unexpectedly, Homo, which suggest similar loading of all fingers during habitual locomotion or hand use. In Pan, however, cortical thickness differs between the fingers, potentially reflecting differential loading during knuckle-walking. Inter- and intra-generic variation in phalangeal cortical bone structure reflects differences in manual behaviours, offering a comparative framework for reconstructing hand use in fossil hominins.

Recognition Performance Analysis of a Multimodal Biometric System Based on the Fusion of 3D Ultrasound Hand-Geometry and Palmprint.

Multimodal biometric systems are often used in a wide variety of applications where high security is required. Such systems show several merits in terms of universality and recognition rate compared to unimodal systems. Among several acquisition technologies, ultrasound bears great potential in high secure access applications because it allows the acquisition of 3D information about the human body and is able to verify liveness of the sample. In this work, recognition performances of a multimodal system obtained by fusing palmprint and hand-geometry 3D features, which are extracted from the same collected volumetric image, are extensively evaluated. Several fusion techniques based on the weighted score sum rule and on a wide variety of possible combinations of palmprint and hand geometry scores are experimented with. Recognition performances of the various methods are evaluated and compared through verification and identification experiments carried out on a homemade database employed in previous works. Verification results demonstrated that the fusion, in most cases, produces a noticeable improvement compared to unimodal systems: an EER value of 0.06% is achieved in at least five cases against values of 1.18% and 0.63% obtained in the best case for unimodal palmprint and hand geometry, respectively. The analysis also revealed that the best fusion results do not include any combination between the best scores of unimodal characteristics. Identification experiments, carried out for the methods that provided the best verification results, consistently demonstrated an identification rate of 100%, against 98% and 91% obtained in the best case for unimodal palmprint and hand geometry, respectively.

Influence of Surface Geometry on Palm and Fist Contact Pressure Distribution During Strikes With the Hand in Automotive Assembly.

The increase in repetitive strain injuries to the hand underscores the need for assessing and preventing musculoskeletal overuse associated with hand-intensive tasks. This study investigates the risk of overload injuries in soft tissue structures of the hand by analyzing the pressure distribution and location of peak pressure in the hand during snap-fit connection assembly in the automotive industry. The influence of the surface geometry of automotive trim components the pressure distribution and force imparted during strikes with the palm and the fist are investigated in a cohort of 30 subjects with extensive experience installing trim parts with snap-fit connections. Using the palm or fist (ulnar hand side) of the dominant hand, the subjects struck a simulation device with a flat, rounded, or edged surface geometry. The average peak force applied was 600 N (±122 N), nearly 3 times the force required to overcome the technical resistance of the snap-fit connector (220 N). Fist strikes exerted a 40% higher mean peak pressure and 18% higher mean pressure than did palm strikes. The pressure distribution in the region of the thenar eminence and soft tissue of the ulnar side of the hand did not differ between fist strikes on flat and edged surfaces. Considering the delicate anatomy of the hand, especially the hypothenar muscles on the ulnar side, assembling connection claps using the fist instead of the palm may prevent repetitive blunt trauma to the sensitive blood vessels and nerves in the palm.

Reinforced Palmprint Reconstruction Attacks in Biometric Systems.

Biometric signals can be acquired with different sensors and recognized in secure identity management systems. However, it is vulnerable to various attacks that compromise the security management in many applications, such as industrial IoT. In a real-world scenario, the target template stored in the database of a biometric system can possibly be leaked, and then used to reconstruct a fake image to fool the biometric system. As such, many reconstruction attacks have been proposed, yet unsatisfactory naturalness, poor visual quality or incompleteness remains as major limitations. Thus, two reinforced palmprint reconstruction attacks are proposed. Any palmprint image, which can be easily obtained, is used as the initial image, and the region of interest is iteratively modified with deep reinforcement strategies to reduce the matching distance. In the first attack, Modification Constraint within Neighborhood (MCwN) limits the modification extent and suppresses the reckless modification. In the second attack, Batch Member Selection (BMS) selects the significant pixels (SPs) to compose the batch, which are simultaneously modified to a slighter extent to reduce the matching number and the visual-quality degradation. The two reinforced attacks can satisfy all the requirements, which cannot be simultaneously satisfied by the existing attacks. The thorough experiments demonstrate that the two attacks have a highly successful attack rate for palmprint systems based on the most state-of-the-art coding-based methods.

Ensemble-Based Bounding Box Regression for Enhanced Knuckle Localization.

The knuckle creases present on the dorsal side of the human hand can play significant role in identifying the offenders of serious crime, especially when evidence images of more recognizable biometric traits, such as the face, are not available. These knuckle creases, if localized appropriately, can result in improved identification ability. This is attributed to ambient inclusion of the creases and minimal effect of background, which lead to quality and discerning feature extraction. This paper presents an ensemble approach, utilizing multiple object detector frameworks, to localize the knuckle regions in a functionally appropriate way. The approach leverages from the individual capabilities of the popular object detectors and provide a more comprehensive knuckle region localization. The investigations are completed with two large-scale public hand databases which consist of hand-dorsal images with varying backgrounds and finger positioning. In addition to that, effectiveness of the proposed approach is also tested with a novel proprietary unconstrained multi-ethnic hand dorsal dataset to evaluate its generalizability. Several novel performance metrics are tailored to evaluate the efficacy of the proposed knuckle localization approach. These metrics aim to measure the veracity of the detected knuckle regions in terms of their relation with the ground truth. The comparison of the proposed approach with individual object detectors and a state-of-the-art hand keypoint detector clearly establishes the outperforming nature of the proposed approach. The generalization of the proposed approach is also corroborated through the cross-dataset framework.

Human thumb consists of three phalanges and lacks metacarpal? A morphometric study on the long bones of the hand.

PURPOSE: For many years, it was thought that the thumb consists of just two phalanges that differentiate it from the other four medial triphalangeal fingers. But there are some old reports that few former scientists believed the thumb has three phalanges and it lacked a metacarpal, and the thumb metacarpal is a phalanx. So this anthropometric study was carried out by investigating the morphology of the long bones of the hand and correlations between the thumb metacarpal and other miniature long bones of the hand. METHODS: We studied anterior-posterior X-ray images of the right hands of 80 individuals from 18 to 65 years old. The exploration targets were the length of all metacarpals (MC), proximal phalanges (PP), middle phalanges (MP), and distal phalanges (DP). Friedman Repeated Measures Analysis of Variance and Dunn's post hoc test were carried out to compare the means of all variables. The correlation between all quantitative factors was done by Spearman Rank Correlation (Spearman's Rho) coefficient. RESULTS: Our results showed that the length of the phalanges and the total length of the fingers are independent of the related metacarpal length (P < 0.001). Also, the thumb metacarpal length in comparison to all bones of the hand was significantly different from all long bones of the hand except the proximal phalanx of the middle finger (P = 1). CONCLUSION: Based on the morphology of the long bones of the hand and the high similarity between the thumb metacarpal and phalanges especially the proximal phalanx of the middle finger, it can be suggested that the current thumb metacarpal is a proximal phalanx of the thumb.

High-resolution MRI of mummified tissues using advanced short-T2 methodology and hardware.

PURPOSE: Evolutionary medicine aims to study disease development from a long-term perspective, and through the analysis of mummified tissue, timescales of several thousand years are unlocked. Due to the status of mummies as ancient relics, noninvasive techniques are preferable, and, currently, CT imaging is the most widespread method. However, CT images lack soft-tissue contrast, making complementary MRI data desirable. Unfortunately, the dehydrated nature and short T2 times of mummified tissues render them practically invisible to standard MRI techniques. Specialized short-T2 approaches have therefore been used, but currently suffer severe resolution limitations. The purpose of the present study is to improve resolution in MRI of mummified tissues. METHODS: The zero-TE-based hybrid filling technique, together with a high-performance magnetic field gradient, was used to image three ancient Egyptian mummified human body parts: a hand, a foot, and a head. A similar pairing has already been shown to increase resolution and image quality in MRI of short-T2 tissues. RESULTS: MRI images of yet unparalleled image quality were obtained for all samples, reaching isotropic resolutions of 0.6 mm and SNR values above 100. The same general features as present in CT images were depicted but with different contrast, particularly for regions containing embalming substances. CONCLUSION: Mummy MRI is a potentially valuable tool for (paleo)pathological studies, as well as for investigations into ancient mummification processes. The results presented here show sufficient improvement in the depiction of mummified tissues to clear new paths for the exploration of this field.

The forearm and hand musculature of semi-terrestrial rhesus macaques (Macaca mulatta) and arboreal gibbons (fam.Hylobatidae). Part II. Quantitative analysis.

Nonhuman primates have a highly diverse locomotor repertoire defined by an equally diverse hand use. Based on how primates use their hands during locomotion, we can distinguish between terrestrial and arboreal taxa. The 'arboreal' hand is likely adapted towards high wrist mobility and grasping, whereas the 'terrestrial' hand will show adaptations to loading. While the morphology of the forearm and hand bones have been studied extensively, functional adaptations in the forearm and hand musculature to locomotor behaviour have been documented only scarcely. In this paper, we investigate the forelimb musculature of the highly arboreal gibbons (including Hylobates lar,Hylobates pileatus,Nomascus leucogenys,Nomascus concolor and Symphalangus syndactylus) and compare this with the musculature of the semi-terrestrial rhesus macaques (Macaca mulatta). Anatomical data from previous dissections on knuckle-walking bonobos (Pan paniscus) and bipedal humans (Homo sapiens) are also included to further integrate the analyses in the scope of catarrhine hand adaptation. This study indicates that the overall configuration of the arm and hand musculature of these primates is very similar but there are some apparent differences in relative size which can be linked to differences in forelimb function and which might be related to their specific locomotor behaviour. In macaques, there is a large development of wrist deviators, wrist and digital flexors, and m. triceps brachii, as these muscles are important during the different phases of palmi- and digitigrade quadrupedal walking to stabilize the wrist and elbow. In addition, their m. flexor carpi ulnaris is the most important contributor to the total force-generating capacity of the wrist flexors and deviators, and is needed to counteract the adducting torque at the elbow joint during quadrupedal walking. Gibbons show a relatively high force-generating capacity in their forearm rotators, wrist and digital flexors, which are important muscles in brachiation to actively regulate forward movement of the body. The results also stress the importance of the digital flexors in bonobos, during climbing and clambering, and in humans, which is likely linked to our advanced manipulation skills.

Triple-Type Feature Extraction for Palmprint Recognition.

Palmprint recognition has received tremendous research interests due to its outstanding user-friendliness such as non-invasive and good hygiene properties. Most recent palmprint recognition studies such as deep-learning methods usually learn discriminative features from palmprint images, which usually require a large number of labeled samples to achieve a reasonable good recognition performance. However, palmprint images are usually limited because it is relative difficult to collect enough palmprint samples, making most existing deep-learning-based methods ineffective. In this paper, we propose a heuristic palmprint recognition method by extracting triple types of palmprint features without requiring any training samples. We first extract the most important inherent features of a palmprint, including the texture, gradient and direction features, and encode them into triple-type feature codes. Then, we use the block-wise histograms of the triple-type feature codes to form the triple feature descriptors for palmprint representation. Finally, we employ a weighted matching-score level fusion to calculate the similarity between two compared palmprint images of triple-type feature descriptors for palmprint recognition. Extensive experimental results on the three widely used palmprint databases clearly show the promising effectiveness of the proposed method.

Prevalence, variants, and morphometrics of Palmaris Longus tendon: a magnetic resonance imaging study.

PURPOSE: The palmaris longus (PL) tendon present a high degree of variations; the commonest is its absence which could reach more than 40% in some populations. The PL tendon is highly relevant in hand reconstructive surgery; however, MRI variations of PL tendon have been exceptionally reported. To this, this study investigated PL tendon variations using MRI in a Lebanese population. METHODS: This is a retrospective study of distal forearm MRI examinations to evaluate the presence, anatomical variations and morphometric of PL tendon. The outcomes were set as overall frequency, gender-based and side-base frequencies, correlations between prevalence and gender/side, morphological variants, thickness, and width of PL tendon. RESULTS: The sample comprised 335 patients including a total of 339 MRI scans. The PL was present in 221 wrists (65.2%), and bilaterally in only one (25%) out of the 4 bilateral cases. All PL were located using the Axial T1 views. Univariate and multivariate analyses showed no correlation with side, gender, or Tesla power. The only morphological variation was a reversed PL in 2 cases (0.6%). The mean width was 4.24 ± 1.2 mm. The mean thickness was 2.75 ± 0.6 mm. CONCLUSION: As far as we know, this is the first study to report the total array of variations of PL tendon using MRI, and its prevalence in a Lebanese population. The mean width of PL tendon calculated with high quality MR imaging was found to be similar to that reported by cadaveric studies.

Ultra-High Frequency Ultrasound, A Promising Diagnostic Technique: Review of the Literature and Single-Center Experience.

OBJECTIVES: Ultra-high frequency ultrasonography (UHFUS) is a recently introduced diagnostic technique which finds several applications in diverse clinical fields. The range of frequencies between 30 and 100 MHz allows for high spatial resolution imaging of superficial structures, making this technique suitable for the imaging of skin, blood vessels, musculoskeletal anatomy, oral mucosa, and small parts. However, the current clinical applications of UHFUS have never been analyzed in a consistent multidisciplinary manner. The aim of this study is to revise and discuss the current applications of UHFUS in different aspects of research and clinical practice, as well as to provide some examples of the current work-in-progress carried out in our center. MATERIALS AND METHODS: A literature search was performed in order to retrieve articles reporting the applications of UHFUS both in research and in clinical settings. Inclusion criteria were the use of frequencies above 30 MHz and study design conducted in vivo on human subjects. RESULTS: In total 66 articles were retrieved. The majority of the articles focused on dermatological and vascular applications, although musculoskeletal and intraoral applications are emerging fields of use. We also describe our experience in the use of UHFUS as a valuable diagnostic support in the fields of dermatology, rheumatology, oral medicine, and musculoskeletal anatomy. CONCLUSION: Ultra-high frequency ultrasonography application involves an increasing number of medical fields. The high spatial resolution and the superb image quality achievable allow to foresee a wider use of this novel technique, which has the potential to bring innovation in diagnostic imaging.

Characterization of afferent corpuscular sensors of the human palmaris brevis muscle.

The palmaris brevis muscle contains numerous muscle spindles to control changes of the muscle length but is devoid of tendon-associated neuronal elements (e.g. Golgi tendon organs or Ruffini-like corpuscles) controlling changes in muscle strength. Pacinian bodies, frequently seen in the palm of the hand, show no direct association to the muscle bundles. The observed innervation pattern of the palmaris brevis muscle points to a specific type of neuronal regulation, present in skeletal muscles with no skeletal connection.

The forearm and hand musculature of semi-terrestrial rhesus macaques (Macaca mulatta) and arboreal gibbons (Fam. Hylobatidae). Part I. Description and comparison of the muscle configuration.

Primates live in very diverse environments and, as a consequence, show an equally diverse locomotor behaviour. During locomotion, the primate hand interacts with the superstrate and/or substrate and will therefore probably show adaptive signals linked with this locomotor behaviour. Whereas the morphology of the forearm and hand bones have been studied extensively, the functional adaptations in the hand musculature have been documented only scarcely. To evaluate whether there are potential adaptations in forelimb musculature to locomotor behaviour, we investigated the forearm and hand musculature of the highly arboreal gibbons (including Hylobates lar, Hylobates pileatus, Nomascus leucogenys, Nomascus concolor, Symphalangus syndactylus) and compared this with the musculature of the semi-terrestrial rhesus macaques (Macaca mulatta) by performing complete and detailed dissections on a sample of 15 unembalmed specimens. We found that the overall configuration of the upper arm and hand musculature is highly comparable between arboreal gibbons and semi-terrestrial macaques, and follows the general primate condition. Most of the identified differences in muscle configuration are located in the forearm. In macaques, a prominent m. epitrochleoanconeus is present, which potentially helps to extend the forearm and/or stabilize the elbow joint during quadrupedal walking. The m. flexor carpi radialis shows a more radial insertion in gibbons, which might be advantageous during brachiation, as it can aid radial deviation. The fingers of macaques are controlled in pairs by the m. extensor digiti secondi et tertii proprius and the m. extensor digiti quarti et quinti proprius-a similar organization can also be found in their flexors-which might aid in efficient positioning of the hand and fingers on uneven substrates during quadrupedal walking. In contrast, extension of the little finger in gibbons is controlled by a separate m. extensor digiti minimi, whereas digits 2 to 4 are extended by the m. extensor digitorum brevis, suggesting that simultaneous extension of digits 2-4 in gibbons might be important when reaching or grasping an overhead support during brachiation. In conclusion, the overall configuration of the forelimb and hand musculature is very similar in gibbons and macaques, with some peculiarities which can be linked to differences in forelimb function and which might be related to the specific locomotor behaviour of each group.