Lower Lumbar and Sacral Projections of Caudal Medullary Expiratory Neurons in the Cat
Respiratory rhythmogenesi’s is organized in the brain stem and respiratory rhythm is then transmitted to the spinal respiratory motoneurons. Expiratory (E) neurons in the caudal nucleus retroambigualis are bulbospinal neurons1 and have axonal branches in the thoracic and the upper lumbar spinal cord2, 3, 4. E neurons exert synaptic effects to the internal intercostal and the abdominal motoneurons monosynaptically and/or via interneurons3, 5, 6. Recently, the autoradiographic tracing method have revealed a projection from the region of the nucleus retroambigualis to the nucleus of Onuf in the sacral spinal cord. In the present experiments, we have examined the lower lumbar (L6–L7) and sacral (S1–S3) spinal projections of physiological identified caudal medullary expiratory neurons.
KeywordsPhrenic Nerve Spinal Projection Lumbar Spinal Cord2 Lower Lumbar Antidromic Activation
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