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SummaryBackground and purpose : Muscle spindle is responsible for the control of skeletal muscle fibers function at rest and movement cycle, and is known as servo agent for voluntary movement. Function of this kinetic neceptor is completely dependent on the γ- ring activity would bring activity of la fiber and group II spindle muscle afferent. Also, there is close functional of muscle relationship between α and γ motor fibers which are important in the regulation of redial fiber function. Aim of this research was to study the activity of γ-ring more accurately in one or two consecutive cord segments, and also determine the α-motor fiber activity considering α- γ -linkage.Because more understanding of physiological mechanisms of γ-ring, and knowing the mode (mannar) of their environmental control, may be a way of underslanding the reason of peripheral factors involved in the onset of involuntary and distonic disorders, so, to be able to help more these group of patients.Materials and Methods : In this study, fifteen normal male. Sprague-Dawely rats with mean weight of 500 mg were selected. And urethane as an an aesthesia (30g/100ml) with dosage of 170 mg/100g body weight of rat was injected intraperoninally. For the study of the nerve fibers, laminctomy was done at the humbosacral regeon and surgery was performed at the first half regon of the tail.Results : Activity of γ-moto-neurons at on one cord segment due to external ear mechanical stimulation coused, the activity of γ-ring on one or two sequential cord segments, Ipselaterally, In a way that, increasing deporalization in la (such) fibers and skeletal of group II afferent fiber on coudal regeon was followed by increasing activity of one or more than one γ fiber. Also, la fibers always have more activity on the activity of homonymous moto neurons, comparing with group II afferent fibers, while the activity of group III afferent fibers, due to stimulation of caudal skin. Did not couse the activity of this group γ-moto neurons.Considering the function of potential range of α-γ-linkage in motor α-fibers (in) during deep anaesthesia, was at the basal rhythem.Conclusion : Duo to external ear mechanical stimulation homonymous moto neurons on one or two sequential segments of cord, caused the more activity of la fiber Ipsilaterally, comparing with with the group II afferents in one or more than one skeletal spindle.But group III afferent fibers activated by caudal skin stimulation, did had no stimulation on homonymous moto neurons. Also, considering the α-γ-linkage no activity was observed on motor fibers. |
