The mechanical function of linked muscles in the guinea fowl hind limb

Abstract

SUMMARYAlthough mechanical linkages between the proximal and distal limb are present in a range of species, their functional significance is unknown. We have investigated the mechanical function of the flexor cruris lateralis pars pelvica (FCLP), flexor cruris lateralis pars accessoria (FCLA) and gastrocnemius intermedia (GI), a system of linked muscles spanning proximal and distal limb segments in the guinea fowl (Numida meleagris) hind limb. The FCLP, which is in the anatomical position of a hamstring muscle, is the primary component of the linkage. It is connected to the distal femur via the FCLA, the tarsometatarsus via the tendon of insertion of the GI and the common Achilles tendon, and the tibiotarsus via a distal tendon of insertion. The FCLP may, therefore, potentially exert moments at the hip, knee and ankle joints depending on the joint angles and the relative states of activation in the three muscles. Evidence presented here suggests that the GI and FCLA act as actively controlled links that alter distal action of the FCLP. The FCLP and GI are coactive in the late swing and early stance phases of the stride, forming a triarticular complex, and likely act together to resist and control ankle flexion immediately after foot-down in addition to providing hip extension and knee flexion moments. The FCLP and FCLA are coactive from mid-through to late stance, acting together as a uniarticular hip extensor. Available evidence suggests that this role of the FCLP and FCLA is of increased importance in inclined running and accelerations. This linkage between a proximal muscle and alternate distal connections allows for functional flexibility, both in terms of the site at which the muscle exerts force and the nature of the muscle's mechanical function. The interactions generated between the proximal and distal limb by linkages of this type suggest that less emphasis should be placed on the distinct functional roles of specific anatomical classes of muscle within proximal and distal limb segments.

Longitudinal and transversal displacements between triceps surae muscles during locomotion of the rat

“…The relative displacements and activation levels of the muscles studied were those occurring in the freely moving animal, thus providing information about the extent of mechanical and functional interaction between muscles in an intact environment and with physiological muscle recruitment. Differential action of synergistic muscles has been observed in several species with a similar approach (Biewener et al, 1998;Daley, 2003;Ellerby and Marsh, 2010;Maas et al, 2009). …”

Humans, geometric similarity and the Froude number: is ‘‘reasonably close’’ really close enough?

“…While the internal characteristics that vary among individuals remain difficult to assess at this time, the externally apparent characteristics of size and shape are knowable and appear to be important for understanding metabolic energy expenditure. The use of a model organism that can be experimentally manipulated and invasively examined, such as the Guinea fowl used by Marsh and colleagues (Carr et al, 2011a; Carr et al, 2011b; Ellerby et al, 2003; Ellerby et al, 2005; Ellerby and Marsh, 2006; Ellerby and Marsh, 2010; Henry et al, 2005; Marsh and Ellerby, 2006; Marsh et al, 2004; Marsh et al, 2006; Rubenson et al, 2006; Rubenson and Marsh, 2009), could provide unique insights into the interplay among the many parameters that influence the relationship between metabolism and mechanical energy.…”

Long-axis rotation: a missing degree of freedom in avian bipedal locomotion

“…Whole-limb kinematics (Gatesy and Biewener, 1991;Abourachid and Renous, 2000;Verstappen et al, 2000;Abourachid, 2001) and whole-body kinetics (Roberts and Scales, 2002;Henry et al, 2005;Daley and Biewener, 2006;Hancock et al, 2007;Birn-Jeffery and Daley, 2012;Andrada et al, 2013a) are typically studied with lateral film or video records. Likewise, analyses of joint rotation are usually restricted to flexion/extension (FE) angles (Sigmund, 1959;Cracraft, 1971;Rylander and Bolen, 1974;Jacobson and Hollyday, 1982;Manion, 1984;Gatesy, 1990;Gatesy, 1999;Johnston and Bekoff, 1992;Abourachid and Renous, 2000;Reilly, 2000;Verstappen et al, 2000;Ellerby and Marsh, 2010;Smith et al, 2010;Nyakatura et al, 2012). Given the relatively small transverse component of the ground reaction force during forward locomotion (Clark and Alexander, 1975;Main and Biewener, 2007;Troy et al, 2009), inverse dynamic studies normally emphasize net FE joint moments as well (Roberts, 2001;Roberts and Scales, 2004;Daley et al, 2007;Rubenson and Marsh, 2009;Andrada et al, 2013b).…”