Figure 1From: Mechanisms of quadriceps muscle weakness in knee joint osteoarthritis: the effects of prolonged vibration on torque and muscle activation in osteoarthritic and healthy control subjects Schematic diagram of the γ-loop. During voluntary muscle contraction, supraspinal centres coactivate the α-motoneuron and γ-motoneuron pools. The γ-motoneuron pool in turn innervates muscle spindle endings via fusimotor nerve fibres, enhancing their firing. Muscle spindles provide a tonic excitatory input to the homonymous α-motoneuron pool via Ia sensory nerve fibres.Back to article page