Immunocytochemical characteristics of elbow, knee and ankle muscles of the five-toed jerboa (Allactaga elater).

Biochemical adaptations of limb myofibres to intensive bipedal hopping were investigated using the five-toed jerboa Allactaga elater as a model in comparison with the rat. Immunofluorescence methods included immunoreactivity to anti-fast and anti-slow MHC and troponin I. There is no specialization of triceps caput mediale for postural function in the minute non-locomotor forelimbs, unlike quadruped mammals. The various elbow extensor heads and the flexor muscles are alike with regard to fibre type population and cross-sectional areas of each type of fibre. The extensor muscle in the elongated hindlimbs of the five-toed jerboa, at both the knee and the ankle joints, differ from each other extensively. One head, made up of an extremely high percentage of type I, fatigue-resistant fibres, is suited to postural function. Two extensor heads at each joint contain a very high percentage of type IIB fibres (having the greatest maximal velocity of contraction) and are able to produce the powerful acceleration needed to trigger the leap. The relative cross-sectional areas of the myofibres are characteristic of hopping locomotion: predominance in number of one type of myofibre in a muscle accompanies greater cross-sectional area, which increases muscle efficiency in either postural or accelerative function of the muscle.

A biomechanical study of the long bones in platyrrhines.

The long bones of 72 individuals of extant platyrrhines, belonging to 17 species (11 genera) were studied by regressions of length, diameters and curvature. Cross-sectional shapes at midshaft and axial and bending strength indicators were also calculated. Results show that forelimb bones scale faster than hindlimb bones, for both length and diameters. Curvature scales faster in the femur than in other bones. Strength indicators showed a high variability in the relative importance of axial and bending loadings. Results are consistent with field observations of locomotor behaviour, mainly as regards quadrupedalism versus suspensory locomotion.

Function and cytochemical characteristics of postural limb muscles of the rhesus monkey: A telemetered EMG and immunofluorescence study.

Using telemetered electromyography and immunocytochemical fibre typing (of both fresh frozen and preserved specimens), the present paper demonstrates clearly that at the elbow, knee, and ankle joints, the rhesus monkey (Macaca mulatta) is endowed with one extensor-muscle head specialized for posture. These postural heads are distinguished by (a) recruitment at low levels to maintain joint position against the effect of gravity, (b) recruitment near maximum levels during walking, and (c) high content and relatively large size of slow, fatigue-resistant (type I) muscle fibres. The nonpostural heads of the investigated muscles were recruited at levels correlated to the strenuousness of the effort and are notable by the small percentage and size of slow muscle fibres. The postmortem stability of the structural properties of myosin makes immunocytochemical fibre typing suitable for the study of preserved cadavers.

The length of the vertebral column of primates: an allometric study.

The length of the vertebral column of 425 primates (151 prosimians, 76 platyrrhines and 198 catarrhines) was related to body mass from bibliographic sources. Regressions were calculated for the whole sample and separately for the three taxonomic groups quoted above. In parallel, the lengths of the cervical, thoracic and lumbar regions were calculated in a sample of 105 primates (30 prosimians, 19 platyrrhines and 56 catarrhines) and partial correlations established. In all cases except one, the correlation coefficients were significant. Of these, 12 correlations (out of 16) scaled with negative allometry (< 0.33), 4 with positive allometry (> 0.33), and in 6 cases the exponents were not significantly different from the criterion for isometry (0.33). The lumbar region showed the highest variability, mainly in platyrrhines and catarrhines. Results from catarrhines are globally the closest to the expectations of elastic similarity. No obvious direct relationship was found between the length of the vertebral column and the number of vertebrae.

Developmental changes in the fibre composition of elbow, knee, and ankle extensor muscles in cercopithecid monkeys.

Developmental changes of muscle fibre composition in the various heads of the elbow, knee, and ankle extensors have been studied in three genera of cercopithecid monkeys. In order to circumvent the technical hindrances of usual histoenzymological procedures (fresh muscles need to be frozen at once at -80 degrees C), immunofluorescence methods were used and technical adjustments were successfully carried out to make the study of formaldehyde-preserved muscles possible. Clear responses to antibodies against adult fast myosin in newborn macaques demonstrated that, at birth, adult myosins have already replaced the fetal isoforms, thus providing a reliable marker for the study of postnatal evolution of the muscle fibre composition. For each one of the three joints, from birth to adulthood, the percentage of slow, fatigue-resistant fibres increases only in that head of the extensor muscle groups which is specialized in maintaining posture by counteracting gravity (the 'postural' head). Hence, the question is raised of the relationships between such cytological evolution, developmental changes in postural behaviour, and body weight increase.

Preliminary note on biometric data relating to the human coraco-acromial arch.

A biometric study based on 20 human scapulae made it possible to specify the variations in the gap of the coraco-acromial arch in relation to its depth and height. A graphic representation in rectangular coordinates, then in spatial representation in relation to the three planes of reference, leads to the following findings: the bony variations in the arch occur essentially: at the coracoid apophysis, and two types of arch can be distinguished depending on the predominance of bony or of ligamentous components.

Gross structure and function of the quadriceps femoris in Lemur fulvus: an analysis based on telemetered electromyography.

Analysis based on telemetered electromyography from the quadriceps femoris of Lemur fulvus, a Malagasy prosimian, during walking, galloping, leaping, and a variety of postural behaviors partially confirms and partially contradicts earlier hypothesized functions of this musculoskeletal complex. As predicted on the basis of morphological criteria (large physiological cross-section and long parallel fibers), the vastus lateralis is of special functional significance in leaping. This relatively large muscle consistently initiates the leap and frequently undergoes a very long period of force enhancement via active stretch. By contrast, the vastus intermedius fails to exhibit increased electrical activity and undergoes little or no active stretch during jumps. The myological details of vastus intermedius (short fibers, no fusion with other components), therefore, cannot be accounted for as adaptations to leaping. Rather, a primary postural role is indicated for the vastus intermedius, because in normal resting postures, with the knee quite flexed, it alone is continuously active. The existence of a fibrocartilaginous superior patella in the tendon of vastus intermedius, however, is most plausibly related to the complex tensile and compressive stresses generated in the tendon during the completely hyperflexed phase of leaping. The phasic patterning of the quadriceps femoris of Lemur fulvus does not point to any special role of the vastus lateralis or vastus intermedius during walking and galloping; it does indicate very different patterns of muscle recruitment in comparison to those in nonprimate mammals and some anthropoid primates. The forward cross walk (diagonal sequence, diagonal couplets) of primates versus the backward cross gait (lateral sequence) of most other mammals probably accounts for some of these differences. Lemur fulvus lacks the degree of elastic storage and release of kinetic energy in the quadriceps femoris that characterizes the gallop of dogs, cats, and Erythrocebus patas.

[Tele-electromyography of various quadriceps femoris muscle bundles during locomotion in a Madagascar lemur (Lemur fulvus)]. / Télé-électromyographie des divers faisceaux du muscle quadriceps femoris au cours de la locomotion chez un lémurien de Madagascar (Lemur fulvus).

The vastus lateralis muscle is of primary importance in leaping inasmuch as it initiates the jumps; on the contrary the activity of the vastus intermedius does not increase during jumping, but it is the only one to be active in quadrupedal resting postures.

[Synchronization of electromyographic and cinematographic recordings. Applications to vertebrate biomechanics]. / Synchronisation d'enregistrements électromyographiques et cinématographiques. Applications á la biomécanique des vertébrés

Synchronizing each frame of the cinema of a moving animal with the corresponding EMG of some muscles permits a precise interpretation of the variations of the electric potentials in that muscle with each phase of the movement. e.g. in the rabbit, three bundles of the masseter muscle function independently during the mastication; in the pigeon, electric potentials appear in both ilio-tibialis and biceps femoris muscles some frames before the actual raising of the leg, when the animal on its perch becomes out of balance.