Short-Term Effects of Muscular Denervation and Fasciotomy on Global Limb Variables during Locomotion in the Decerebrate Cat

Abstract

The motor system is capable of preserving the trajectories during locomotion of task level variables such as limb length and limb orientation in the face of paralysis of major muscle groups. This compensation is accomplished by the adjustment of the kinematics of joints other than the one most affected by the paralysis. The conservation of these task level variables could be accomplished quickly by feedback regulation or intrinsic mechanics, or by a longer-term adaptive process. We investigated the immediate effects of denervation of the triceps surae muscles in one limb of stepping, decerebrate cats to determine whether task level variables were preserved by short-term regulatory or intrinsic mechanisms. We further investigated the effects of disruption of the crural fascia in conjunction with denervation of the triceps surae muscles to determine whether the system consisting of multi-articular muscles of the thigh and crural fascia provided some contribution toward the preservation of limb length and orientation. Denervation led to substantial increases in ankle yield during stance, as previously observed, but also to significant decreases in limb length during early stance. Disruption of the crural fascia did not lead to increased ankle yield but, instead, to evidence for decreased propulsion. The results suggest that the preservation of task level variables observed in other studies does not result from online error correction or intrinsic properties of the musculoskeletal system but, by inference, from longer-term neural adaptation.

Hind limb myology of the southern brown bandicoot (Isoodon obesulus) and greater bilby (Macrotis lagotis) (Marsupialia : Peramelemorphia)

“…Future analysis of the axial skeleton, sacrum and pelvis will help to clarify the differential demands of digging and bounding locomotion in these species. In the lower hind limb we observed a difference in the relative length of the muscle bellies (Stahl and Nichols 2011). In addition to such connections between the fascia and muscles of the limb, distinct tensor muscles inserting onto the deep fascia (m. tensor fasciae latae and m. tensor fasciae cruralis) were observed.…”

The motor and the brake of the trailing leg in human walking: leg force control through ankle modulation and knee covariance

“…Intra-leg and inter-muscular reflex mechanisms may contribute to the monitoring and control of ankle torque generation (Wilmink and Nichols 2003; Stahl and Nichols 2011). However, the inherent stiffness of medial and lateral gastrocnemius couples the knee and ankle, resulting in inter-joint stability (Nichols 1999), so a passive or structural mechanism for ankle-knee coupling is also possible.…”

“…It has been suggested, for instance, that opposing forces in locomotion may have the beneficial effect of passively stabilizing the system while increasing maneuverability (Sefati et al, PNAS 2013). Previous work in cats has revealed neuromechanical coupling between ankle and knee action, suggesting that existing mechanisms for ankle-knee coordination may refine and stabilize leg force control during steady state walking (Nichols 1999; Wilmink and Nichols 2003; Stahl and Nichols 2011). We hypothesized that individual control of ankle torques would be the greatest contributor to joint torque variance structure for modulating trailing leg force ( H2 ), but that the ankle and knee would covary to provide a supplementary stabilizing effect on leg force ( H3 ).…”

Progressive adaptation of whole-limb kinematics after peripheral nerve injury

“…The possibility for immediate recovery of whole-limb kinematics has been examined, but only in cats in which descending motor commands have been experimentally altered. Under conditions of acute decerebration ( Stahl and Nichols, 2011 ) or chronic spinalization ( Bouyer et al, 2001 ), the animal does not immediately conserve normal whole-limb kinematics. All considered, the early stages of whole-limb response to partial denervation of ankle extensors remains unknown for conscious animals with intact central nervous systems.…”