Morphoclinal variation in the anthropoid shoulder.

A morphocline in the organization of the shoulder joint is demonstrated among anthropoid primates. This metrical test supports the view that hominoid distinctions are monophyletic in origin. The primates that are behaviorally and functionally convergent on hominoids are only partially convergent or are not convergent in shoulder morphology.     

Morphometric analysis of Cartesian coordinates of the human skull

A method for locating the three dimensional coordinates of cranial landmarks with respect to the Frankfort, midsagittal, and coronal planes is presented. Sliding calipers were used to obtain the distances from left and right porion and apex to each landmark, except for a few points where spreading calipers are required. In the present example, 35 landmarks (for a total of 105 measurements) were located for each of 35 Peruvian precolumbian skulls. These distances were entered into a program (SKULL) which calculates the Cartesian coordinates of each landmark. The XYZ coordinates of each landmark contain all the information necessary for calculation of the distances between any two landmarks, and these distances may also be obtained as output from program SKULL, if desired (595 distances if all 35 landmarks are used). Reliability of the location of coordinates was determined by comparing computed distances among selected landmarks from program SKULL with traditional anthropometric measurements. Satisfactory agreements were found. Direct multivariate analysis of the coordinates of the landmarks produced insights not available in traditional multivariate analysis of conventional anthropometric measurements.     

Analysis of the shoulder in brachiating spider monkeys.

Adult spider monkeys (Ateles geoffroyi and A. paniscus) were conditioned to brachiate on a rope mill (an arboreal analogue of a treadmill). The postures and excursions of the shoulder girdle were studied by cineradiography. These data, together with conventional cinematographic and anatomical studies, permit reassessment of some characteristic structural and functional features of the shoulder in brachiators. During the propulsive phase, the shoulder joint moves caudad from fifth cervical to seventh cervical levels; at the same time, the joint moves dorsad (from a frontal plane midway between the first thoracic vertebra and the manubrium, to a frontal plane through the spinous processes) and slightly mediad. Spider monkeys position the scapula principally on the dorsum of the thorax, in contrast to quadrupedal primates which maintain a more lateral position (even in suspended postures). During brachiation, the scapula rotates a total of 35°; most of this rotation (20°) occurs in the non-propulsive phase when the free arm is being elevated to secure a new handhold. The sigmoidal shape, twisting of proximal relative to distal ends, and elongation of the clavicle in spider monkeys and other brachiators appear to be related to the specialized positioning of the shoulder girdle on the dorsum of the thorax. Shoulder and elbow movements contribute to the efficiency of the swing in terms of the dynamics of a pendulum.     

Evolution of femur and tibia in higher primates: Adaptive morphological patterns and phylogenetic diversity

Seventy six metrical traits measured on the femur and tibia of three higher primate groups —Ceboidea, Cercopithecoidea, Hominoidea have been processed by various univariate and multivariate statistical methods to survey the process of evolution of the morphology of the femur and tibia in higher primates. Intragroup and intergroup variability, similarity and differences as well as various aspects of scaling and sexual dimorphism have been analyzed to study adaptive trends and phylogenetic diversity in higher primates, in individual superfamilies and to explore the adaptive morphological pattern of early hominids and basic differences between hominids and pongids. Two basic morphotypes of the femur and tibia in higher primates have been determined. They are (1) advanced hominoid morphotype (hominids and pongids) and (2) ancestral higher primate morphotype (platyrrhine and cattarrhine monkeys, early hominoids, and hylobatids). Cebid lower limb bones are adapted to arboreal quadrupedalism with antipronograde features while femur and tibia of cercopithecid monkeys are basically adapted to the semi-arboreal locomotion. Early hominoids (Proconsul) and hylobatids are morphologically different from pongids; some features are close toAteles or other monkey species. Pongids and hominids are taken as one major morphological group with different scaling and some functional and morphological similarities. Numerous analogous features were described on the lower limb skeleton ofPan andPongo showing analogous ecological parameters in their evolution. Major morphological and biomechanical trends are analyzed. It is argued that early advanced hominoid morphology is ancestral both to the pongids and to early hominids. The progressive morphological trend in early hominids has been found fromA. afarensis with ancestral hominid morphology, toH. habilis with an elongated femur and structural features similar to advanced hominids. A detailed phylogenetic analysis of higher primate femur and tibia is also presented.     

Functional activity characteristics of individuals with shoulder dysfunctions

Shoulder-related dysfunction affects individuals’ ability to function independently and thus decreases quality of life. Functional task assessment is a key concern for a clinician in diagnostic assessment, outcome measurement, and planning of treatment programs. The purpose of this study was to test the reliability of the FASTRAK 3-dimensional (3-D) motion analysis and surface electromyography (sEMG) systems to analyze 3-D shoulder complex movements during functional tasks and compare motion patterns between subjects with and without shoulder dysfunctions (SDs).For the test, sEMG and 3-D motion analysis systems were used to characterize the functional tasks. Twenty-five asymptomatic male subjects and 21 male subjects with right shoulder disorders performed four functional tasks which involved arm reaching and raising activities with their dominant arms. Reliability was estimated by the intraclass correlation coefficient (ICC). Motion pattern was compared between two groups using mixed analysis of variances (ANOVAs). Shoulder complex kinematics and associated muscular activities during functional tasks were reliably quantified (ICC = 0.83–0.99) from the means of three trials. Relative to the group without SDs, the group with SDs showed significant alteration in shoulder complex kinematics (3°–40°) and associated muscular activities (3–10% maximum). Scapular tipping, scapular elevation, upper trapezius muscle function, and serratus anterior muscle function may have implications in the rehabilitation of patients with SDs.     

Assessing the affinities of fossils using canonical variates and generalized distances

Canonical variate analysis and generalized distances are commonly used multivariate statistical techniques for assessing the comparative morphology of living and fossil primates. Some common pitfalls of these methods when used to analyze fossil specimens are: (1) ignoring the possibility that a fossil belongs to a group other than one of the predefined reference samples (i.e., restricted versus unrestricted approaches to classification), (2) misinterpreting probabilities of group membership (i.e., posterior versus typicality probabilities), and (3) failing to understand how sample sizes influence multivariate ordinations in trying to effectively illustrate the morphometric affinities of a fossil (i.e., weighted versus unweighted analyses with fossils entered indirectly or directly into the analysis). To better understand canonincal variate analysis and generalized distances, the workings of these methods are portrayed graphically as a series of rotations and rescaling of data plotted in a multivariate data space. The influence of sample sizes and the importance of higher-numberer canonical variates are emphasized. Simple examples taken from the literature illustrate how the different approaches to including a fosil in canonical variate analysis may affect the multivariate results upon which physical anthropologists base their interpretations of the fossil's morphology.     

Effects of different movement directions on electromyography recorded from the shoulder muscles while passing the target positions

PurposeWe compared electromyography (EMG) recorded from the shoulder joint muscles in the same position for different movement directions.MethodsFifteen healthy subjects participated. They performed shoulder elevation from 0° to 120°, shoulder depression from 120° to 0°, shoulder horizontal adduction from ?15° to 105°, and shoulder horizontal abduction from 105° to ?15°. The target positions were 90° shoulder elevation in the 0°, 30°, 60°, and 90° planes (0°, 30°, 60°, and 90° positions). EMG signals were recorded from the supraspinatus (SSP) muscle by fine-wire electrodes. EMG signals from the infraspinatus (ISP), anterior deltoid, middle deltoid, and posterior deltoid muscles were recorded using active surface electrodes.ResultsDuring elevation and horizontal abduction, the SSP showed significantly higher activity than that shown during depression and during horizontal adduction in the 0°, 30°, and 60° positions. During elevation, the ISP showed significantly higher activity than during depression and during horizontal adduction in the 90° position. During horizontal abduction, the ISP showed significantly higher activity than during depression in the 90° position.ConclusionsWhen the movement tasks were performed in different movement directions at the same speed, each muscle showed characteristic activity.     

Biomechanical model of the human shoulder joint--II. The shoulder rhythm

A method to investigate the rhythm of the human shoulder, i.e. the interplay between the motion of constituent parts of the shoulder, has been devised and tested. The method is based upon numerical evaluation of low dose roentgenstereophotogrammetric motion pictures of subjects equipped with radiation dense implantations in the bones. Evaluation of the method shows that it may be used in determining motion patterns and that the employed interpolation techniques can be used to simulate motions not actually performed in the laboratory. The shoulder rhythm has been previously poorly investigated and quantified results published pertain to one plane only. Our results on motion patterns correlate with previous investigations. With this method, we show that the absolute position of the bones varies significantly between individuals while the relative displacement of the bones during motion exhibit similarities. In particular the results show that, under normal conditions, the individual rhythm is very stable and insensitive to small hand-loads.     

懒猴肩关节的多变量分析

在懒猴与其它灵长类肩关节局部解剖的基础上,对肩关节有关指数的多变量分析结果表明,与骨骼相比,肩关节肌的种间差别明显较大。肩胛盂宽指数、肩胛骨指数和锁肱指数对种的区分有重要意义。懒猴具有类似于叶猴三角肌、大圆肌和喙肱中肌较远的止点及发达的背阔肌和斜方肌颅侧部,增强了肩关节的运动,表现出适应树栖四足运动的特征。而懒猴粗壮的肱骨、较长的锁骨和较长的肱骨,是攀爬型和四足倒挂运动的适应结果。     

The femur in early human evolution.

Uni- and multivariate analyses of 5 fossil and 215 extant hominoid femora show that two morphological patterns of hominid femora existed about two million years ago. Femora classified as Homo sp. indet. (KNMER 1472 and 1481) are more like Homo sapiens although not identical.Those classified as Australopithecus robustus (SK 82 and 97) and A. boisei (KNM-ER 1503) are similar to one another but uniquely different from any living hominoid. The strong mophological constrasts imply biomechanical and possible locomotor differences, although these are as yet unknown.     

Development of human cerebellar nuclei. Morphometric study

The morphometric development of the human cerebellar nuclei was examined in 9 fetuses (16-40 weeks of gestation; WG), an infant (2 months old) and 2 adults (16 and 63 years old). With the morphological observation of serial sections of the brain containing the cerebellar nuclei, the authors measured sections to get several morphometric parameters: the volume of nuclear column and number, packing density and cell body area of neurons. Each nucleus (dentate, emboliform, globose and fastigial nucleus) was recognized even at 16 WG. Nerve cells containing Nissl bodies were observed in all nuclei after 23 WG. Degenerative changes were detected in some neurons for every nucleus at 21 and 23 WG. Three stages were observed in the developmental course of nuclear volume and neuronal packing density: the primary or undifferentiated stage at 16 WG, the secondary stage with variability at 21-32 WG and the tertiary stage with monotonous increase (nuclear volume) or gradual decrease (neuronal packing density) after 35 WG. No significant correlation between neuronal number and gestational age was noticed for every nucleus. The analysis of cell body area (neuronal size) demonstrated that the dentate neurons developed after the intermediate or fastigial neurons. It is concluded that there is a critical period between slightly before 20 WG and slightly after 30 WG, matched with the secondary stage in the development of the cerebellar nuclei.     

Morphometric evaluations of the human nervous system

It is very important to evaluate and accurately understand the various conditions of the human nervous system. In this review article, we introduce several morphometric reports that are proven to be accurate from the view point of various errors (range of tissue shrinkage ratios, microscopic multiple counting, artifacts of microscopic structures, etc.). We review the following aspects of the selected reports: methodology, developmental research, neuronal differences, gender differences, aging process and miscellaneous (nerve fibers, unmyelinated fibers, in relation to neuropathology, clinical image-analysis and immunohistochemistry).     

Morphometric study of the human muscle spindle

OBJECTIVE: To study the morphometric characteristics of the human muscle spindle in normal muscle and to investigate the influence of aging. STUDY DESIGN: The following variables were studied in 72 spindles: area and diameter of the spindle; thickness of the capsule; number, area and diameter of fibers; and number and area of nuclei. RESULTS: In deltoid and extensor digitorum brevis muscles, a reduction in the diameter of the spindle as a function of age was found, while no statistically significant change in the variables as a function of age was observed in the quadriceps femoris and biceps muscles. In the deltoid, a reduction in the number of fibers and an increase in their diameter were also observed. CONCLUSION: These findings could prove useful in the study of the spindle in relation to disease.     

Locomotor adaptations within the Cercopithecus Genus: a multivariate approach.

Multivariate analysis as a technique for investigating locomotor differentiation among primates has proven its power and usefulness in many studies on various skeletal dimensions. In these analyses primate genera were distributed and sometimes clustered in a manner that was interpretable based on current knowledge of gross locomotor differences. In an effort to advance our understanding of arboreality and terrestriality in primates, the present research involves a careful look for the most subtle morphological differences in locomotor behavior. It is believed that by looking at such subtle shape differences an understanding of what it means morphologically for a primate to be either more or less arboreal may be achieved. The species within the primate genus Cercopithecus were analyzed. This genus includes species which may be placed along a habitat (ground-living to tree-dwelling) or activity spectrum. The different habitats or activity patterns clearly require slight variations in patterns of movement, which in turn may require subtle structural adaptations. Multivariate analyses of 67 postcranial variables on seven species within the genus allowed detection of slight degrees of morphological variation. However, when morphological differences are small, size variance among specimens may take on an inflated importance. A substantial amount of work was devoted to finding the least biased method of removing size variance from the variables while incorporating a discrete size variable into the study. Using these transformed skeletal variables, interspecific groupings were discovered. Much of this infrastructure is then related to differing locomotor behavior and provides an insight into the fine structure of primate locomotor adaptation in an arboreal habitat.     

Activation of shoulder muscles in healthy men and women under isometric conditions

Purpose: Due to the low osseous lead of the shoulder joint a large portion of the shoulder muscles, in addition to executing movements, deals with stabilising tasks. This requires a permanent readjustment of the intermuscular co-ordination of all involved muscles. The aim of the study was to verify the existence of gender dependent differences in intramuscular co-ordination patterns of shoulder muscles.

Method: Fifteen healthy men and nine healthy women, who executed 24 isometric exercises in sagittal, frontal and horizontal planes with a loading of 50% of their individual isometric maximum force, were investigated. In every plane, four angular positions were chosen and both opposite force directions were measured, respectively. SEMG was taken from 13 muscles of the shoulder and the upper arm. Due to inter-individual differences SEMG amplitudes were normalised. Results: Gender specific differences of functional intermuscular co-ordination patterns could be proven systematically. Women showed less activation of muscles acting in the main force direction. In addition, those muscles less necessary for the actual force production were more activated in women than in men.

Conclusions: Functionally comparable shoulder function showed a gender dependency in terms of functional intermuscular co-ordination.     

On the biomechanics of human shoulder complex--II. Passive resistive properties beyond the shoulder complex sinus

In multi-segmented total-human-body models the most difficult and the least successful modeling of a major articulating joint has been the shoulder complex because of the lack of appropriate biomechanical data as well as the anatomical complexity of the region. In this paper, quantitative results on the three-dimensional passive resistive properties beyond the voluntary shoulder complex sinus are presented by applying the methodology developed in part I. Constant-restoring-force(moment) contours are established for the shoulder complex and the numerical results are presented for the three subjects tested. In addition, functional expansions are presented for the voluntary and restoring force(moment) contours using spherical coordinates.     

Dietary reconstruction of the Amphipithecidae (Primates, Anthropoidea) from the Paleogene of South Asia and paleoecological implications

The primate family, Amphipithecidae, lived during the early Cenozoic in South Asia. In this study, the diet of late middle Eocene amphipithecids from the Pondaung Formation (Central Myanmar) is characterized using three different approaches: body mass estimation, shearing quotient quantification and dental microwear analysis. Our results are compared with other Paleogene amphipithecids from Thailand and Pakistan, and to the other members of the primate community from the Pondaung Formation. Our results indicate a majority of frugivores within this primate community. Pondaungia and “Amphipithecus” included hard objects, such as seeds and nuts, in their diet. Folivory is secondary for these taxa. Myanmarpithecus probably had a mixed diet based on fruit and leaves. Contrasting results and a unique dental morphology distinguish Ganlea from other amphipithecids. These render interpretation difficult but nevertheless indicate a diet tending towards leaves and fruit. However, the anterior dentition of Ganlea suggests that this taxon engaged in seed predation, using its protruding canine as a tool to husk hard fruits and obtain the soft seeds inside. Bahinia and Paukkaungia, two other Pondaung primates, are small (<500 g) and therefore would have depended on insects as their source of protein. As such, they occupied a very different ecological niche from Pondaung amphipithecids. This primate community is then compared with the Eocene-Oligocene primate communities of the Fayum from North Africa. Similarities between the late middle Eocene Pondaung primate community and extant equatorial and tropical South American primate communities are noted.