![]() Both sides of each cadaveric head were dissected using different skull base approaches to demonstrate the entire course of the abducens nerve from the pontomedullary sulcus to the lateral rectus muscle. Ten cadaveric heads were examined using Ã-3 to Ã-40 magnification after the arteries and veins were injected with colored silicone. The aim of this study is to demonstrate and review the detailed microsurgical anatomy of the abducens nerve and surrounding structures along its entire course and to provide its topographic measurements. Joo, Wonil Yoshioka, Fumitaka Funaki, Takeshi Rhoton, Albert L Microsurgical anatomy of the abducens nerve. ![]() A precise comparison of the dynamics and timing of the eye movements further suggests that a temporal organization of both NRPCs is needed to reproduce the complexity of the oculomotor behavior during REM sleep. the cholinergic activation of the NRPC induces oculomotor phenomena that are somewhat similar to those described during REM sleep. ABD motoneurons showed phasic activities associated with ABD PGO-like waves during bursts of rapid eye movements, and tonic and phasic activities related to eye position and velocity during alertness. Although tonic effects were dependent on the level of drowsiness, phasic effects were always present and appeared along with normal saccades when the animal was vigilant. Phasic effects consisted of bursts of rhythmic rapid eye movements directed contralaterally to the injected side along with PGO-like waves in the lateral geniculate and ABD nuclei. Tonic effects consisted of ipsiversive rotation to the injected side, convergence, and downward rotation of the eyes. unilateral microinjections of carbachol in the NRPC induced tonic and phasic phenomena in the oculomotor system. six female adult cats were prepared for chronic recording of eye movements (using the scleral search-coil technique), electroencephalography, electromyography, ponto-geniculo-occipital (PGO) waves in the lateral geniculate nucleus, and ABD motoneuron activities after microinjections of the cholinergic agonist carbachol into the NRPC. The aim of this work was to characterize eye movements and abducens (ABD) motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis (NRPC). ![]() The functional visual requirements of the ferret may explain these fundamental differences.Įye movements and abducens motoneuron behavior after cholinergic activation of the nucleus reticularis pontis caudalis. Compared with cat and squirrel monkeys, the ferret LR motor units contract more slowly yet more powerfully. Samples of LR were found to contain an average of 4,687 fibers, indicating an LR innervation ratio of 25.6:1. The abducens nucleus was examined with horseradish peroxidase conjugated with the subunit B of cholera toxin histochemistry and found to contain an average of 183 motoneurons. The average fatigue index of whole muscle was 0.408. Whole muscle twitch contraction time was 16.7 ms with a mean twitch tension of 3.32 g. Single-unit fatigue index averaged 0.634. The abducens nucleus motor units showed a twitch contraction time of 15.4 ms, a mean twitch tension of 30.2 mg, and an average fusion frequency of 154 Hz. In addition to individual motor units, the whole LR muscle was evaluated for twitch, tetanic peak force, and fatigue. Of these motor units, 56 innervated the lateral rectus (LR) muscle alone, while 6 were split between the LR and retractor bulbi (RB) muscle slips. Using extracellular stimulation, 62 individual motor units in the ferret abducens nucleus were evaluated for their contractile characteristics. ![]() We believed it important, therefore, to study extraocular whole muscle as well as single motor unit physiology in the ferret. The ferret has become a popular model for physiological and neurodevelopmental research in the visual system. Anatomic and physiological characteristics of the ferret lateral rectus muscle and abducens nucleus.īishop, Keith N McClung, J Ross Goldberg, Stephen J Shall, Mary S
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