Differential activation of psoas major and rectus femoris during active straight leg raise to end range

The purpose of this study was to investigate the activation of the hip flexor and abdominal muscles during an active straight leg raise (ASLR) to end range of hip flexion. Data were recorded from nine healthy men. Fine-wire electromyography (EMG) electrodes were inserted into psoas major (PM), and surface electrodes were placed over rectus femoris (RF), rectus abdominis, obliquus externus abdominis (OE), and obliquus internus abdominis/transversus abdominis (OI/TrA). EMG and kinematic data were obtained during concentric, hold (at end range) and eccentric phases of an ASLR. Concentric and eccentric movements were divided into three phases (early, mid, and late). Onsets of EMG relative to the onset of the ALSR movement and EMG amplitudes in each phase were compared between muscles. Onsets of the PM (–33 ± 245 ms) and RF (-3 ± 119 ms) EMG prior to leg elevation were significantly earlier than those of the OE and OI/TrA. PM EMG showed highest activation in the late concentric, hold, early eccentric phase, and was significantly higher than RF EMG. OI/TrA EMG was significantly greater in mid and late concentric, hold, and early eccentric phase than other phases. During the ASLR, unlike RF, PM EMG continues to increase towards the end range of hip flexion. Activation of OI/TrA muscle may be involved in control trunk and pelvic movement.     

Morphology and evolution of the wing bullae in South American Leptophlebiidae (Ephemeroptera)

Insects were the first animals to take to the skies, and have been flying for over 320 million years. The order Ephemeroptera is, or at least is part of, the most early-diverging lineage of extant winged insects. The extant species present a very short adult life span, mainly dedicated to reproduction and dispersal of eggs. Mating and egg-laying behavior depend on flight. Wings are structures to fly and as such face a number of physical and physiological challenges. The convex curvature along the anterior–posterior axis of the wing generates a camber that must be carefully regulated. One of the most interesting ways of wing bending is provided by the bullae, which have been defined as short sections of flexible chitin, where the flexion lines cross veins. Although the bullae have been frequently used as taxonomic characters, there is no study focused on their morphology, although their prevalence on the wings of mayflies strongly suggests a role in flight. In order to identify evolutionary trends of these structures within Ephemeroptera, we constructed a matrix with comparative anatomy data of the bullae from whole mounts of the wings of 300 specimens belonging to 70 species of several mayfly families, as well as scanning microscopy samples of selected specimens. We also surveyed the number of bullae and their distribution in the wings of the different species within the South American Leptophlebiidae clade. We optimized the characters onto the latest published phylogeny for Leptophlebiidae.