Gamma [chi] motorneurons, which transmit impulses to special skeletal muscle fibres, called intrafusal
fibres, part of the muscle spindle.
Gamma motor neurons can adjust the sensitivity of the intrafusal
fibers by innervating these intrafusal
fibers of the muscle spindle (41).
stretch receptor discharge frequency from Ia afferents can contribute up to 30% of the motoneuron excitation (Gandevia, 2001), SS-induced reductions in afferent excitability could adversely affect muscle force.
The phenomenon of muscle history is thought to arise from the spontaneous formation of stable, non-recycling intrafusal
cross-bridges between actin and myosin filaments when muscle is held at constant length.
Its are composed of 3-12 intrafusal
muscle fibers, of which there are three types:
The motoneuron plays a role in changing the length of the intrafusal
fibers and adjusting sensitivity of the muscle spindles.
The second type of muscle fiber, intrafusal
fibers, functions within muscle spindles and is innervated by gamma motor neurons and sensory Ia neurons (see Figure 1 ).
reported that a liquid diet and unilateral extraction cause a reduction in the diameter of extrafusal, and later intrafusal
Using vertebral movement and intact paraspinal muscles to determine the distribution of intrafusal
fiber innervation of muscle spindle afferents in the anethesized cat.
For example, stretch-shortening cycle fatigue appears to influence both extrafusal and intrafusal
muscle, which may describe a form of neural fatigue (Avela and Komi, 1998; Avela et al.
When the release of acetylcholine is blocked, the denervation of the extrafusal and intrafusal
muscle fibers occurs.
Supporting evidence is based on observations that state, vibration can only increase maximal isometric contraction force and EMG activity when fatigue is present in the intrafusal
fibres (Bongiovanni and Hagbarth, 1990) or when a-fibre are blocked (Hagbarth et al.