Evidence for presynaptic inhibition of muscle spindle
Ia afferents in man.
Such a system would control the prosthetic hand via muscle contraction and would sense the tension and length changes transmitted from the prosthetic hand via muscle spindles
and skin sensors, allowing more natural sensory feedback and control of the prosthetic device.
The patella tendon reflex is a monosynaptic reflex that included 1a-afferent and an alpha-motorneuron, and should be the best mechanism to study the sensitivity of the muscle spindles
Spinal manipulation has been shown to stimulate the muscle spindle
and Golgi tendon organ afferents evoking paraspinal reflexes that can inhibit motorneuron excitability and, thus, relax skeletal muscle (8).
Liu JX, Thornell LE and Pedrosa-Domell F (2003): Muscle spindles
in the deep muscles of the human neck: A morphological and immunocytochemical study.
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 ).
Since the muscles of velopharyngeal closure are not well endowed with muscle spindles
, vibration is contraindicated as a treatment and has not been used to date (Clark, 2003).
In limb musculature, the presence and function of muscle spindles
and the associated stretch reflexes are consistent relative to muscle size [19-21].
1986) found a decrease in the ability to reproduce joint angles after a series of interval running sprints to fatigue, suggesting that this decreased ability was due to a loss of efficiency of muscle spindles
Strong evidence exists that in addition to ligamentous and capsular receptors, muscle spindles
and possibly golgi tendon organs located in muscles, tendons and at musculotendinous junctions mediate joint positional and joint movement sense (Grigg 1994, Jami 1992, Jozsa et al, 1993, Wilkerson and Nitz 1994).
However, vibration may cause an indirect involvement of muscle spindles
, where other sensory inputs may influence gamma (y) motoneuron activity, causing changes to spindle input (Gandevia 2001).
One of these differences is that the discharge rate of Ia afferents from muscle spindles
during eccentric contraction is higher than that during other types of muscle contraction, since an eccentric contraction involves the development of tension in the muscle spindle
while the whole muscle is being lengthened (Burke, 1978; Ribot-Ciscar and Roll, 1998).